1. business and industrial
2. agriculture and forestry
3. crops and seed

Hydraulic Aspects on the Design and Performance
of Drip Irrigation System
By
Abu Obaida Mohammed El Obeid
B.Sc.(Agric)
University of Mansoura A.R.E.
1980
A Thesis Submitted to the University of Khartoum in Partial
Fulfillment of the Requirements for the Degree of Master of
Science in Agriculture
(Irrigation)
Supervision
Dr. Amir Bakheit Saeed
Department of Agricultural Engineering
Faculty of Agriculture
University of Khartoum
2006
‫ﺑﺴﻢ ﺍﷲ ﺍﻟﺮﺣﻤﻦ ﺍﻟﺮﺣﻴﻢ‬
‫ﻗﺎﻝ ﺗﻌﺎﱃ ‪:‬‬
‫(ﻓﺎﻥ ﻟﻢ ﻳﻜﻦ ﻭﺍﺑﻞ ﻓﻄﻞ ﻭ ﺍﷲ ﺑﻤﺎ ﺗﻌﻤﻠﻮﻥ ﺑﺼﻴﺮ)‬
‫(‪)256‬ﺳﻮﺭﺓ ﺍﻟﺒﻘﺮﺓ ﺍﻵﻳﺔ‬
Dedication
This work is dedicated to
my father's soul,
... my mother,
... my wife and lovely kids,
...and all my friends with ever lasting love.
ACKNOWLEDGMENT
My praise be to ALLAH who gave me health and power to complete this
work ... I would like to express my truthful gratitude and thanks to my
supervisor Dr. AMIR BAKHIET SAEED for his leader ship, encouragement
and help to carry out this work.
My greatest gratitude and appreciation are extended to my family their
support through all stages of this work.
Special gratitude goes to Mohammed Omer and my colleagues who
helped me in the lay out and data collection.
Finally ... I would like to express deep thanks to all who gave me some
help during the progress of this work.
Table of contents
Page
Table of Contents ...... ...... ..... ..... ..... ..... ..... ..... ..... ...... ..... ..... .... i
List of Tables ... ...... ..... ..... ..... ..... ..... ..... ..... ...... ..... ..... ..... .. ... vi
List of Figures ... ...... ..... ..... ..... ..... ..... ..... ..... ...... ..... ..... ..... ... viii
List of Plates ... ...... ..... ..... ..... ..... ..... ..... ..... ...... ..... ..... . .... .... ix
Dedication ...... ...... ..... ..... ..... ..... ..... ..... ..... ...... ..... ..... ... . ... .... x
Acknowledgement ... ...... ..... ..... ..... ..... ..... ..... ..... ...... ..... .... . ... xi
English Abstract . ...... ..... ..... ..... ..... ..... ..... ..... ...... ..... .. ..... ..... xii
Arabic Abstract ... ...... ..... ..... ..... ..... ..... ..... ..... ...... ......... ..... .... xv
CHAPTER ONE: INTRODUCTION . ..... ..... ..... ..... ..... ..... ..... ..... 1
CHAPTER TWO: LITERATURE REVIEW... ..... ..... ..... ..... ..... .... 4
2.1 Introduction ...... ...... ...... ..... ..... ..... ..... ..... ..... ...... ..... ..... .... ..4
2.2 Irrigation definition .. ...... ...... ..... ..... ..... ..... ..... ..... ..... ...... ......4
2.3 Irrigation methods ..... ..... ..... ..... ..... ..... ..... ..... ...... ..... ..... ...... 5
2.3.1 Surface irrigation...... ...... ..... ..... ..... ..... ..... ..... ..... ...... ..... .....5
2.3.2 Sub-surface irrigation. ...... ..... ..... ..... ..... ..... ..... ..... ...... ..... . 5
2.3.3 Sprinkler irrigation .. ...... ..... ..... ..... ..... ..... ..... ..... ...... ..... ...5
2.3.4 Drip (Trickle) irrigation ...... ...... ...... ...... ..... ..... ..... ..... ...... ...5
2.4 Concept of drip irrigation ...... ...... ...... ...... ..... ..... ..... ..... ..... ...6
2.5 Definition of drip irrigation ...... ...... ...... ...... ..... ..... ..... ..... ......6
2.6 Historical review. ...... ..... ..... ..... ..... ..... ..... ..... ...... ..... ..... ..... 6
2.7 Advantages of drip irrigation . ...... ...... ..... ..... ..... ..... ..... ..... . 7
2.8 Disadvantages of drip irrigation ........... ..... ..... ..... ........... ...... ...8
2.9 Types of drip irrigation ...... ...... ...... ..... ..... ..... ..... ..... ..... ..... ..9
2.9.1 Bubbler irrigation ...... ...... ...... ...... ..... ..... ..... ..... ..... ..... ..... .9
2.9.2 Drip (trickle) irrigation ...... ...... ...... ...... ..... ..... ..... ..... ..... ... .9
2.9.3 Micro- Sprayers ...... ...... ...... ...... ..... ..... ..... ..... ..... ..... ..... ...9
2.9.4 Mobile drip system ...... ...... ...... ...... ..... ..... ..... ..... ..... ..... .... 9
2.10 System components ...... ...... ...... ...... ..... ..... ..... ..... ..... ....... 10
2.10.1 Pump ...... ...... ...... ...... ..... ..... ..... ..... ..... ..... ..... ...... ......... 10
2.10.2 Control head ...... ...... ...... ...... ..... ..... ..... ..... ..... ..... ..... .... 11
2.10.3 Valves ...... ...... ...... ...... ..... ..... ..... ..... ..... ..... ..... ...... .....
11
2.10.4 Backflow preventers ...... ...... ...... ...... ..... ..... ..... ..... ..... .. .11
2.10.5 Pressure and flow regulators...... ...... ...... ...... ..... ..... ..... .... .11
2.10.6 Filters ...... ...... ...... ...... ..... ..... ..... ..... ..... ..... ..... ...... ..... ...11
2.11 Fertilizing methods.... ...... ...... ...... ..... ..... ..... ..... ..... ..... ...... 14
2.12Main and submain lines ...... ...... ...... ....... ..... ..... ..... ..... ..... ...15
2.13 Laterals . ...... ...... ..... ..... ..... ..... ..... ..... ..... ...... ..... ..... ..... ....15
2.14 Manifolds ...... ...... ...... ...... ..... ..... ..... ..... ..... ..... ..... ...... .... .15
2.15 Fittings...... ...... ...... ...... ..... ..... ..... ..... ..... ..... ..... ...... ..... ....16
2.16 Emission point ...... ...... ...... ...... ..... ..... ..... ..... ..... ..... ..... .....16
2.16.1 Line source-tubing ...... ...... ...... ...... ..... ..... ..... ..... ..... ..... ..16
2.16.2 Emitters ...... ...... ...... ...... ..... ..... ..... ..... ..... ..... ..... ...... .... 16
2.17 Hydraulics of emitters ...... ...... ...... ...... ..... ..... ..... ..... ..... ... 18
2.17.1 Reynold's number (RN) ...... ...... ...... ...... ..... ..... ..... ..... ..... .18
2.17.2 Emitter discharge exponent (X) ...... ...... ...... ...... ..... ..... ..... .18
2.17.3 Emitter manufacturing coefficient of variation (CV) ...... ......19
2.17.4 Classification of emitter manufacturing
coefficient of variation (CV) ............ ..... ..... ..... ..... ..... ..... .19
2.18 Determining of allowable pressure difference ...... ...... ...... ......20
2.19 Laterals hydraulics ..... .......... ...... ...... ...... ..... ..... ..... ..... ..... .21
2.19.1 Blasius equation ...... ...... ...... ...... ..... ..... ..... ..... ..... ..... ......21
2.19.2 Darcy-Weisbach equation ..... ..... ..... ..... ..... ..... ...... ...... .... 22
2.19.4 Christensen's friction factor (F) ...... ...... ...... ...... ..... ..... ..... 22
2.19.3 Hazen-Williams equation ...... ...... ...... ...... ..... ..... ...... ..... ..23
2.20 Uniformity of drip irrigation (EU%) ...... ...... ...... ...... ..... .... 23
2.21 Soil moisture content ...... ...... ...... ...... ..... ..... ..... ..... ..... ......24
2.21.1 Field capacity (F.C) ...... ...... ...... ...... ..... ..... ..... ..... ..... ..... 24
2.21.2 Permanent wilting point (P.W.P) ..... ...... ..... ..... ..... ..... ........ 24
2.21.3Available water ..... .......... ...... ...... ..... ..... ..... ..... ..... ..... ..... 24
2.22 Measurement of soil moisture content ..... ..... ........... ...... .... .24
2.23 Drip and plant rooting ...... ...... ...... ..... ..... ..... ..... ..... ..... ...... 25
2.24 Drip irrigation system design ...... ...... ...... ..... ..... ..... ..... ...... . 25
2.25 Emitter spacing ...... ...... ...... ..... ..... ..... ..... ..... ..... ..... ...... ......25
2.26 Number of emitters per plant ...... ...... ...... ..... ..... ..... ..... ...... 26
2.27 Crop water requirement (CWR) ...... ...... ...... ..... ..... .......... .
27
2.28 The net crop water requirement (NCWR) ...... ..... ..... ..... ..... .29
2.29 Gross irrigation requirement (Ig) ...... ...... ...... ..... ..... ..... ...... 30
2.30 Irrigation efficiency for drip system..... ..... ..... ..... ..... ..... ....... .31
2.31 depth of water to be applied by irrigation...... ...... ..... ..... ......
32
2.32 Irrigation set time for drip...... ...... ...... ...... ..... ..... ..... ..... ...... 32
2.33 Irrigation frequency...... ...... ...... ...... ..... ..... ..... ..... ..... ...... .
33
2.34 System capacity...... ..... ..... ..... ..... ..... ..... ... ...... ...... .........
33
2.35 Squash...... ...... ...... ...... ..... ..... ..... ..... ..... ..... ..... ...... ........ ... 33
2.36 Practices on drip irrigation... ...... ...... ...... ..... ..... ...... ..... ......
34
CHAPTER THREE: MATERIALS AND METHODS ..... ..... .. .. 42
3.1 Site description and Experimental layout...... ...... ..... ...... ...... .... 42
3.2 Land preparation..... ..... ..... ..... ..... ...... ..... ..... ..... ..... ..... ...... ...42
3.3 Drip irrigation system description ..... ..... ..... .... ..... ..... ..... ....... 43
3.3.1 Pump unit.... .... ....... ...... ...... ...... ..... ...... ..... .. ..... ..... .... ... 43
3.3.2 Control unit ...... .... ..... ..... ..... ..... .... ..... .......... ..... .......... ..... 43
3.3.3 The main line ... ..... ..... ..... ..... ...... ...... ..... ........ ...... ..... ...... 43
3.3.5The lateral lines.. .... ..... ..... ..... ..... ...... ..... ...... ..... ..... ..... .......44
3.3.6 Emitters .... ..... ....... ...... ..... ...... ...... ..... .... ..... .... .... .... .......44
3.4 Furrow method .... ...... ..... ...... ...... ...... ..... ...... ...... ...... ...... ... 44
3.5 The squash data collection ..... ..... ..... ..... .... ...... ...... ..... ..... . .. 44
3.6 Measurements .... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... .. 45
3.6.1 Measurement of the discharge ...... ..... ...... .... ...... ........ ....... ...45
3.6.2 Measurement of the pressure ..... ...... ..... ..... ..... ..... ..... ... .... 45
3.6.3 Measurement of the soil moisture content .... ..... ..... .... .... .... 45
3.6.4 Measurement of the wetted soil depth...... ...... ...... ...... ..... ..... 45
3.7 Experimental procedure..... ..... ..... ..... ...... ..... ..... ..... ..... ..... ... 46
Chapter four: RESULTS AND DISCUSSING ..... ..... ..... ........ 51
4.1 Emitters discharge...... ...... ...... ...... ..... ..... ..... ..... .... ..... ..... ... 51
4.2 Emitters exponent (X) and discharge coefficient (Kd) ..... ..... ..... 51
4.3 Manufactory variation (CV) ...... ...... ..... ..... ...... ..... ..... ..... ....
52
4.4 T he relation between the laterals lines length and emitters
discharge ...... ...... ...... ...... ..... ..... ..... ..... ..... ..... ..... ..... 52
4.5 Emission uniformity (EU %) ...... ..... ..... ..... ..... ..... ..... ..... .... 54
4.6 Reynold's number (Rn) and Blasius factor (f)..... ...... ...... ........ ...55
4.7 The pressure variation (head loss) along the lateral length.... .. . ..55
4.8 The calculated allowable pressure difference (head loss).... ...... 59
4.9 Calculated pressure difference (head loss) according to
Darcy-Weisbach equation ..... ......... ...... ...... ........ ....... .......
59
4.10 Calculated pressure difference (head loss) according to
Hazen- Williams equation ..... ...... ...... ...... ..... ..... ..... ..... .... 60
4.11 Squash water requirement ....... ...... ..... ...... ..... ...... ...... ..... .... 63
4.12 Irrigation efficiencies for the first season ..... ..... ..... ..... ...... ...63
4.12.1 Emission uniformity for squash lines (EU %) first season . ... 64
4.12.2 Water application efficiency first season...... ....... ...... ...... .... 65
4.13 Irrigation efficiencies for the second season ….. ….. ….. ..... 65
4.13.1 Emission uniformity for squash lines second season ...... ........65
4.13.2 Water application efficiency ...... ..... ...... ...... ..... ..... ..... .......66
4.14 Efficiency of water use (first season) ..... ...... ..... ..... ..... ...... . 66
4.15 Efficiency of water use (second season) ...... ..... ..... ..... ..... .....66
4.16 Soil properties .... ..... ...... ..... .. ..... ...... ..... ..... ..... ..... ..... .....67
4.17 Squash plant under drip irrigation ..... ..... .......... ..... ...... ..... .... 68
4.18 Squash plant under furrow line...... ...... .... ..... .... ..... ... ....... 68
4.19 Data analysis .... .......... ...... ...... .... ..... .... ..... ...... .... ....
69
CHAPTER FIVE: CONCLUSIONS AND RECOMMENDATIONS..76
5.1 Conclusions ….. ….. …… … … …… …… ….. ….. …… …... 76
5.2 Recommendations ….. …… …… …. …… …… …… ……. .. 76
REFERENCES …. ….. …… …… ….. ….. ….. ….. ….. ….. …… . 77
APPENDICES …. ….. ….. ….. …… ….. ….. ….. ….. ….. ….. …... 80
List of Tables
Table No.
Title
Page
2.1 Recommendations of the filters types ...... ..... ..... . ............ ..... .... 13
2. Classification of screen and particle size ..... ...... . ...... ..... ..... .... 14
2.3 Classification of emitters coefficient of manufacturing
variation (CV) ...... ...... ...... ...... ...... ...... ...... ..... ....... ........... ....20
2.4 Emitters spacing according to type of soil.... ..... ..... ..... ...... ..... 26
2.5 Water storage efficiency (Ks %) .... ..... ..... ..... ..... ....... ..... ..... ...31
2.6 A comparison between surface, sprinkler, and drip
irrigation systems ..... ...... ..... ...... ..... ..... ....... ..... ..... ... 34
2.7 A comparison between production of some crops under different
irrigation systems.. ..... ..... ..... ..... ..... ....... ........ .... ....... ..... ..... 35
3.1 Emitters specifications . ...... ..... ..... ..... ..... ..... ..... ..... .... ....... 44
4.1 Emitters discharge..... ...... ..... ..... ..... ..... ..... ..... ..... .... ..... ........51
4.2 Emitters discharge exponent (X) and discharge coefficient(kd) .. ..51
4.3 Manufacturing variation (CV)..... ..... ..... ..... ..... ..... ..... ..... . ... 52
4.4 Relation between lateral lines 40 m length and
emitters discharge ..... ..... ..... ....... ..... ...... ..... ..... ..... .. 52
4.5 Relation between lateral lines 60 m length and
emitters discharge ..... ..... ..... ..... ..... ...... ..... ......... ....... . 53
4.6 Relation between lateral lines 80 m length and
emitters discharge ..... ..... ..... ..... ..... ...... ..... .......... ....... 53
4.7 Emission uniformity for different types of emitters (EU %).........54
4.7 Pressure variation 40 m lateral length.......... ...... ...... ..... ........ . 56
4.8 Pressure variation 60 m lateral length.... ..... ...... ..... ..... .... ...... . 56
4.9 Pressure variation 80 m lateral length.. ..... ..... ..... ........ ...... ... . 57
4.10 Summary of results for pressure variation (head loss) ....... ..... . 57
4.11 Calculated allowable pressure difference
according to ASAE technique...... ...... ..... ..... ..... ........
59
4.12 Calculated pressure difference according to
Darcy-Weisbach equation ...... .... ..... ..... .. ..... .....
60
4.13 Calculated pressure difference according to
Hazen-Williams equation....... ..... ..... ..... ..... ..... ..... ..
60
4.15 Estimating squash water requirement.... ...... ..... ......... .... ......63
4.16 Squash lines emission uniformity (first season).... ..... ...... ...... 64
4.17 Squash lines emission uniformity (second season)..... ...... ...... 65
4.18 Squash plant parameters (first season)...... ..... ..... .... ...... ....... 66
4.21 Summary of analysis of variance.... ....... ...... ...... ..... ........ .... 69
List of Figures
Figure No.
Page
2.1 Drip irrigation components ..... ..... ..... ..... ...... ..... ...... .....
36
2.2 Some common types of emitters and tubing's. ..... ...... ..... ..
37
2.3 Wetted profile.... ..... ..... ...... ..... ..... ..... ..... ..... ...... ...... ...
37
3.1 Layout for hydraulic studies..... ..... ..... ..... ..... ...... ..... .....
47
3.2 Layout for studies on water requirements..... ..... ..... ..... .......... 48
4.1 Pressure variation for 0.5 bar beginning pressure ...... ...... .... 58
4.2 Pressure variation for 1.0 bar beginning pressure..... ..... ......... 58
4.3 Comparison of the head loss between Hazen-Williams equation,
Darcy-Weisbach equation, ASAE technique, and actual
measured pressure under 5 m working pressure ...... ...... ...... . 61
4.4 Comparison of the head loss between Hazen-Williams equation,
Darcy-Weisbach equation, ASAE technique, and actual
measured pressure under 10 m working pressure ...... ...... ...... . 62
List of Plates
Plate No.
Page
2.1 Control head with a venturi tube.. ..... .... ..... .... ......... ..... ..... . 38
2.2 Control valve. ..... ..... ..... ..... ...... ..... ..... .... ..... ..... ......... .......38
2.3 Manifold layout ...... ...... ...... ...... ..... ..... ..... ..... ..... .......... ...39
2.4 Three types of drip irrigation filters ... ...... ..... ........... ..... ........40
2.5 Some important drip irrigation fittings ........... ...... ..... ..... ...... 41
3.1 Built-in (GR) tube.... ..... ..... ..... ...... ..... ...... ...... ...... ....... ..... 49
3.2 Built-on (Turbo-Key) emitter ..... ..... ..... ...... ..... ..... ..... ...... .. 49
3.3 Pressure gauge (one bar capacity). ..... ..... ..... ..... ..... ..... ..... .. 50
3.4 Disc filter ...... ....... ....... ....... ....... ....... ..... ..... ..... ..... ..... ..... 50
4.1General view of the experimental field .. ..... ..... ..... ..... ..... ...
71
4.2 Squash plant..... ..... ..... ..... ..... ..... ..... ..... ...... ..... ...... ..... ..... 71
4.3 Furrow line (control).. ..... ..... ..... ..... ..... ..... ...... ..... ..... ..... ... 72
4.4 Built-on above soil surface line ..... ..... ..... ..... ..... ..... ...... ..... 72
4.5 Built-on and built-in (sub surface) ...... ...... ...... ...... ..... ..... ..... .73
4.6 Built-in above soil surface with pressure gauge connected .. ..... 73
4.7 Furrow line showing high weed infestation..... ...... ..... ..... ....... 74
4.8 Emission (in-line dripper) .. ..... ...... ..... ..... ..... ..... ..... ..... ..... 74
ABSTRACT
Hydraulic characteristics, irrigation efficiency and water use
efficiency, using drip irrigation system were studied under Shambat
conditions, during 2003 to 2005. A complete randomized block
experimental design was used for three lateral lengths (40,6o,80 m), two
emitters types: built-in (GR), built-on (Turbo-Key) and two pressures
(0.5, 1.0 bar). The 40 m lateral lines were placed either on the soil
surface, or 10 cm below the surface. Squash was used as the indicator
plant and furrow irrigation as a control.
Higher Emission uniformities (EU) within the range of (88-96.3%)
were obtained from the built-in emitters as compared to a range of
(84.4- 95.3%) given by the built-on emitters, with the three lateral lengths
operating under the pressure levels.
The manufacturing coefficient of variations (CV) and the discharge
exponent ( X ) were found to be 0.01, 0.011 and 0.384, o.433 for the
built-in and built-on emitters respectively, hence both of them can be
classified as excellent and partially pressure compensating emitters.
The Darcy-Weisbach and Hazen-Williams equations gave similar
values of friction losses in lateral lines compared to the experimental
measured pressure, and the pressure variation was within the allowable
value of the later length at the limit of 50 m.
The Penman-Monteith formula gave crop water requirement
(ETsquash) of 4.8 mm /day for quash.
The yield of squash increased by 59.6 %, 55.6% and 55.2% for the
built-in, built-on above soil surface and built-in emitters 10 cm below soil
surface respectively as compared to that obtained by the conventional
furrow method. However the yield decreased by 18.1% when the built-on
emitters were buried 10 cm below the soil surface which was attributed
mainly to emitters clogging.
‫ﻣﻠﺨﺺ اﻟﺪراﺳﺔ‬
‫أﺟﺮﻳﺖ هﺬﻩ اﻟﺪراﺳﺔ ﺑﻬﺪف دراﺳﺔ اﻟﺼﻔﺎت اﻟﻤﻤﻴﺰة ﻟﻬﻴﺪروﻟﻴﻜﺎ ﻧﻈﺎم اﻟﺮي ﺑ ﺎﻟﺘﻨﻘﻴﻂ‪ ،‬آﻔ ﺎءة اﻟ ﺮي‪،‬‬
‫آﻔﺎءة اﺳ ﺘﺨﺪام اﻟﻤﻴ ﺎﻩ و ﻣﻘﺎرﻧ ﺔ ذﻟ ﻚ ﺑ ﺎﻟﺮي اﻟ ﺴﻄﺤﻲ )اﻟ ﺴﺮاب(‪ .‬ﺗ ﻢ اﺳ ﺘﺨﺪام ﻧﻈ ﺎم اﻟﻤﺮﺑﻌ ﺎت ﻓ ﻲ‬
‫اﻟﺘﻮزﻳ ﻊ اﻟﻌ ﺸﻮاﺋﻲ ﻟﻠﺨﻄ ﻮط ﻓ ﻲ ﺗﻨﻔﻴ ﺬ اﻟﺘﺠﺮﺑ ﺔ اﻟﺤﻘﻠﻴ ﺔ اﻟﺘ ﻲ أﻗﻴﻤ ﺖ ﺑﺎﻟﻤﺰرﻋ ﺔ اﻟﺘﺠﺮﻳﺒﻴ ﺔ ﻟﺠﺎﻣﻌ ﺔ‬
‫‪2005 -2003‬اﻟﺨﺮﻃﻮم ‪ ،‬ﺷﻤﺒﺎت‪.‬ﻓﻲ اﻟﻔﺘﺮة ﺑﻴﻦ ﻋﺎﻣﻲ‬
‫ﺗﻢ ﺗﺼﻤﻴﻢ و ﺗﺮآﻴﺐ ﻧﻈﺎم اﻟﺮي ﺑﺎﻟﺘﻨﻘﻴﻂ ﻟﻴﺘﻜﻮن ﻣﻦ ﺛﻼث ﺧﻄﻮط ﺛﺎﻧﻮﻳﺔ ذات أﻃﻮال ﻣﺨﺘﻠﻔﺔ‬
‫ﻣﺘ ﺮ( ﻟﻨ ﻮﻋﻴﻦ ﻣﺨﺘﻠﻔ ﻴﻦ ﻣ ﻦ اﻟﻨﻘﺎﻃ ﺎت‪ ،‬ﻧﻘﺎﻃ ﺎت داﺧ ﻞ اﻟﺨ ﻂ )ﺟ ﻲ‪-‬ﺁر( و ﻧﻘﺎﻃ ﺎت ‪) 40, 60, 80‬‬
‫ﻋﻠﻰ اﻟﺨﻂ )ﺗﻮرﺑﻮ – آﻲ( ﺗﺤﺖ ﺿﻐﻄﻴﻦ ﺗﺸﻐﻴﻠﻴﻴﻦ ﻣﺨﺘﻠﻔﻴﻦ )ﻧﺼﻒ ﺑﺎر و واﺣﺪ ﺑﺎر(‪.‬‬
‫ﻣﺘ ﺮ ﺗﺤ ﺖ ﺿ ﻐﻂ ﺗ ﺸﻐﻴﻠﻲ واﺣ ﺪ ﺑ ﺎر و ‪40‬ﺗﻤﺖ زراﻋﺔ ﻧﺒﺎت اﻟﻜﻮﺳﺎ آﻤﺆﺷﺮ ﻋﻠﻰ ﺧﻄﻮط ﺑﻄ ﻮل‬
‫ﺳ ﻢ ﺗﺤ ﺖ ﺳ ﻄﺢ اﻟﺘﺮﺑ ﺔ‪ ،‬و ﻋﻠ ﻰ ﺳ ﻄﺢ اﻟﺘﺮﺑ ﺔ( ﺑﺎﻹﺿ ﺎﻓﺔ ﻟﺨ ﻂ ﻟﻠ ﺮي ‪10‬ﻋﻠﻰ وﺿﻌﻴﻦ ﻣﺨﺘﻠﻔ ﻴﻦ )‬
‫اﻟﺴﻄﺤﻲ )اﻟﺴﺮاب( ﻟﺘﺘﻢ اﻟﻤﻘﺎرﻧﺔ ﺑﻪ‪.‬‬
‫( ﻣﻘﺎرﻧﺔ ﺑﺎﻟﻨﻘﺎﻃﺎت ﻋﻠﻰ ‪%95.9 %95.1,‬آﺎن ﻣﻌﺎﻣﻞ اﻧﺘﻈﺎم اﻟﺘﻨﻘﻴﻂ أﻋﻠﻰ ﻟﻠﻨﻘﺎﻃﺎت داﺧﻞ اﻟﺨﻂ )‬
‫( ﻟﻠﺜﻼث ﺧﻄﻮط ﺗﺤﺖ ﺿﻐﻄﻴﻲ اﻟﺘﺸﻐﻴﻞ اﻟﻤﺬآﻮرة‪%96 ،%94.5 .‬اﻟﺨﻂ )‬
‫و ‪ 0.384‬و ﺛﺎﺑ ﺖ أس اﻟﺘ ﺼﺮﻳﻒ ﻟﻠﻨﻘﺎﻃ ﺎت‪ 0.010‬و ‪0.011‬آ ﺎن ﻣﻌﺎﻣ ﻞ اﻹﺧ ﺘﻼف اﻟﺘ ﺼﻨﻴﻌﻲ‬
‫ﻟﻠﻨﻘﺎﻃﺎت داﺧﻞ اﻟﺨﻂ وﻋﻠﻰ اﻟﺨﻂ ﻋﻠ ﻰ اﻟﺘ ﻮاﻟﻲ‪ ،‬ﺣﻴ ﺚ ﺗ ﺼﻨﻒ ﻧﺘ ﺎﺋﺞ ه ﺬﻩ اﻟﻨﻘﺎﻃ ﺎت ﺑﺄﻧﻬ ﺎ ‪0.433‬‬
‫ﻣﻤﺘﺎزة و ﻣﻌﻮﺿﺔ ﻟﻠﻀﻐﻂ ﺟﺰﺋﻴًَُﺎ ‪.‬‬
‫ﺗﻢ ﺣﺴﺎب ﻓﻮاﻗﺪ اﻟﻀﻐﻂ اﻟﻨﺎﺗﺠﺔ ﻋﻦ اﻹﺣﺘﻜﺎك ﺑﻮاﺳﻄﺔ ﻣﻌﺎدﻟﺘﻲ دارﺳﻲ‪ -‬واﻳﺰﺑﺎخ‬
‫و هﺎزﻳﻦ‪ -‬وﻟﻴﺎﻣﺰ و ﻟﻘﺪ أﻋﻄﺖ اﻟﻤﻌﺎدﻟﺘﻴﻦ ﻧﺘﺎﺋﺞ ﻣﺘﻘﺎرﺑﺔ ﻟﺘﻠﻚ اﻟﺘﻲ ﺗﻢ ﺣﺴﺎﺑﻬﺎ ﻣﻦ ﺧﻄ ﻮط اﻟﺘﺠﺮﺑ ﺔ‪،‬‬
‫ﻣﺘﺮ ﻟﻠﺨﻄﻮط اﻟﻔﺮﻋﻴﺔ‪50.‬آﻤﺎ آﺎن اﻧﺨﻔﺎض اﻟﻀﻐﻂ ﻓﻲ اﻟﺤﺪود اﻟﻤﺴﻤﻮح ﺑﻬﺎ ﺣﺘﻰ ﻃﻮل‬
‫ﺣﺴﺐ ﻣﻌﺎدﻟﺔ ﺑﻨﻤﺎن‪ -‬ﻣﻮﻧﺘﻴﺚ ﺣﻴﺚ آﺎﻧ ﺖ )‪(ETsquash‬ﺗﻢ ﺣﺴﺎب اﻻﺣﺘﻴﺎﺟﺎت اﻟﻤﺎﺋﻴﺔ ﻟﻨﺒﺎت اﻟﻜﻮﺳﺔ‬
‫ﻣﻢ‪ /‬ﻳﻮم‪4.8 .‬‬
‫ﻟﻠﻨﻘﺎﻃﺎت داﺧﻞ اﻟﺨ ﻂ ﻓ ﻮق ‪ 55.2 %‬و‪59.6 % ، 55.6 %‬ﺗﻔﻮق اﻹﻧﺘﺎج ﻟﻨﺒﺎت اﻟﻜﻮﺳﺎ ﺑﺤﻮاﻟﻲ‬
‫وﺗﺤﺖ ﺳﻄﺢ اﻟﺘﺮﺑﺔ واﻟﻨﻘﺎﻃﺎت ﻋﻠﻰ اﻟﺨﻂ ﻓﻮق ﺳﻄﺢ اﻟﺘﺮﺑﺔ ﻋﻠ ﻰ اﻟﺘ ﻮاﻟﻲ ﻣﻘﺎرﻧ ﺔ ﺑ ﺎﻟﺮي اﻟ ﺴﻄﺤﻲ‬
‫ﻟﻠﻨﻘﺎﻃﺎت ﻋﻠﻰ اﻟﺨ ﻂ ﺗﺤ ﺖ ﺳ ﻄﺢ اﻟﺘﺮﺑ ﺔ و ‪ 18.1%‬ﻓﻲ ﺣﻴﻦ اﻧﺨﻔﺾ ﺑﺤﻮاﻟﻲ اﻟﺘﻘﻠﻴﺪي )اﻟﺴﺮاب(‬
‫ﻳﻌﺰى ذﻟﻚ ﻟﻺﻧﺴﺪاد اﻟﻤﺘﻜﺮر ﻟﻠﻨﻘﺎﻃﺎت‪.‬‬
CHAPTER ONE
Introduction
The major constraints to produce more food to meet the
increasing
demands of the world population are land and water. In many parts of
the
world the amount and timing of rainfall are not adequate to meet the
moisture requirement of crops. Water needs to be applied artificially
through an irrigation technique to supplement rainfall.
Sudan is an agricultural country, rich in natural resources. But
land
and water need to be utilized efficiently for self satisfaction in food and
fibre, and with the excess for export. The cultivable land is estimated to
amount up to about 105 million hectares of which only 7.4 million
hectares
is under rain fed agriculture and about 1.3 million hectares under
irrigation.
The water resources at Sudan are rain, underground aquifers,
permanent and
seasonal rivers. River Nile and its tributaries are
considered
the main conventional source of water for reliable agricultural
development.
However this source is governed by international agreements of which
the
most famous are the two bilateral agreements between Egypt and
Sudan,
signed in 1929 and 1959. According to the 1959 Nile Water
Agreement,
Sudan is allotted an annual share of 18.5 milliard m3 as measured at
Aswan
in Egypt . Nevertheless, additional supplies of water can be made
available
through water conservation projects such as saving water losses by
evaporation and runoff in the swampy (Sudd) areas in the southern
region
of the country. Jongli Canal is one of these promising projects but had
not
been completed for security reasons.
Other approaches to conserve water can be through improving and
/ or
modernizing water application techniques at the on farm level.
The traditional method adopted in Sudan is the surface irrigation
mainly with low efficiencies but there are serious efforts for
improvement.
These include precision leveling by the laser technology coupled with
long
furrow irrigation whereas the use of the hydoflume is still under
preliminary investigation.
Irrigation modernization is accepted as a strategic option to
improve
water use efficiency and increase total production and economic
output.
The over head systems, particularly the centre pivot system have
shown
good success under Sudan conditions. On the other hand the use of
drip
irrigation system is still confined (mainly plastic
houses), small
private
farms, wind break trees and landscaping.
There are many areas in Sudan which are adaptable to drip
irrigation
for their soil characteristics, water scarcity and /or low quality. Such
areas
are mainly found in Northern, Eastern and River Nile, North Kordufan
and
Darfour states. The use of drip irrigation under Sudan open field
conditions
is rapidly disseminating and getting popularity.
This study is conducted with a view to achieving the following
objectives:
• To evaluate the performance of two types of drip emitters namely;
the built-in (GR) and the built-on (Turbo-Key). The evaluation will
consider important hydraulic parameters for the two types of the
emitters using: the rate of emitter outflow (discharge) as affected
by pressure, coefficient of variation, lateral length, and location
(above or below soil surface).
• To evaluate growth and production of squash crop under open field
conditions as compared to the conventional surface (furrow) irrigation
method.
CHAPTER TWO
Literature review
2.1 Introduction
Drip irrigation is one of the most recent irrigation systems in the world.
It
has the concept of compensating the actual transpiration of the plant plus
the
over need of the plant growth. The system is widely applied today despite
some of the shortage symptoms observed in the high initial cost and
settlement
of installments. This system is well and quickly disseminating worldwide
specially in dry countries of desert nature since it provides waters of hard
renewal and high cost.
Water is becoming a very scarce resource. If farmers want to ensure
their survival for the future they must employ and adhere to stringent water
conservation methods (Arid Lands technologies, 1998) .
Drip irrigation is the most efficient method of irrigation. While
sprinkler
systems are can reach efficiency of 75% →85%, drip systems can reach
efficiency 90% or more. For this reason drip is the preferred method of
irrigation in the desert regions and arid lands. Moreover drip irrigation has
other
benefits, which make it useful almost anywhere. It is easy to install, to
design to
reduce plant disease, and can be inexpensive when are to be irrigated
unleveled
lands.
2.2 Irrigation definition:
Irrigation is the artificial application of water to the soil for the
purpose of
crop production. Irrigation water is applied to supplement the water
available
from rainfall and the contribution to soil moisture from ground water. In
many
arid and semiarid areas of the world amount and timing of rainfall are not
adequate to meet the moisture requirements of crops and irrigation essential
to
raise crops necessary to the needs of food and fibre. (Michel,1978).
2.3 Irrigation methods:
Irrigation may be accomplished by four different ways:
1- Direct surface application (Surface irrigation).
2- Applying water below soil surface (Subsurface irrigation).
3- Spraying water overhead (Sprinkler irrigation).
4- Applying water in a limited zone of the field area (Drip irrigation).
2.3.1 Surface irrigation:
In this method the water is applied directly to the soil surface from a
channel at the upper reach of the field. Water may be distributed by any
one of
the following systems as stated by (Khalil, 1998).
• Basins.
• Borders or strips.
• Conventional furrow or their modifications.
2.3.2 Subsurface irrigation:
Water is applied below the soil surface. It reaches plant roots through
the
capillary action, and may be introduced through open ditches or under
ground
pipes (Michel,1978).
2.3.3 Sprinkler irrigation:
In this method the water is sprayed in the air and allowed to fall like
rain.
The spray is developed by creating pressure through nozzles, (Khalil,1998).
2.3.4 Drip or trickle irrigation:
Drip or trickle irrigation is the newest of all the commercial methods
of
water application. It is described as the frequent, slow application of water
to
the soil through mechanical devices called emitters or applicators located at
selected points along the water delivery lines (Jensen, 1993).
2.4 Concept of drip irrigation:
The basic concepts of drip irrigation systems are to provide near
optimal soil moisture content in the root zone of the plant. Drip
irrigation of outdoors crops dates back to 1960 where some trails in
Israel replaced the idea of the soil as a storage reservoir with the
concept of irrigation keeping up with evaprotranspiration on a daily
basis, (Keller and Kamelli, 1975; Jensen, 1993)
2.5 Definition of drip irrigation:
Drip irrigation is also commonly refered to as trickle irrigation,
low
flow irrigation, micro irrigation, bubblers, they all have similar
design and management criteria. These systems deliver water for
the individual plant or rows of plants. The outlets are generally
placed at short intervals along small tubing, and unlike surface or
sprinkler irrigation only the soil near the plant is watered. The
outlets include emitters, orifices, bubblers and micro-sprays or
micro-sprinklers with flow ranging from 2 to over 200 liter / hour, (
Schwab, etal., 1993).
2.6 Historical review:
Drip irrigation was born in Germany in 1869 where subsurface
irrigation was performed in combination with drainage systems, in
which short porous clay pipes were used. In 1912 the first
subsurface drip irrigation was reported using iron pipes in U.S.A,
but it was highly expensive as being practical. In 1925-1932 some
experts in France and Russia used subsurface drip irrigation. in
England it was used between 1945-1948 to irrigate tomato plants in
greenhouses. Technological development of plastic pipes after the
second world war made the use of drip irrigation system practical.
Micro irrigation research began in Germany about 1860, and in the
1940th it was introduced to England especially for watering and
fertilizing plants in greenhouses. With increased availability of
plastic pipe and the development of emitters in Israel in the 1950s,
it has since become an important method of irrigation in Australia,
Europe, Israel, Japan, Mexico, South Africa, and the United States
(Schwab, etal., 1993).
2.7 Advantages of drip irrigation:
1- A major advantage of trickle irrigation systems is that the close
balance
between applied water and crop evaprotranspiration
reduces
surface
runoff and deep percolation to a minimum (Ceunca,1989).
2-
For perfect drip irrigation system design, about 40% of the
irrigation
water is saved with an application efficiency of 85% -95% as
compared-with other irrigation systems.
3- Trickle systems produce higher ratio of yield per unit area and
yield
per unit volume of water than typical surface or sprinkler irrigation
systems (Ceunca,1989).
4- Labur requirements are lowered and the system can be readily
automated, (Abbas, etal., 1992).
5water
Frequent or daily application of water keeps the salts in the soil
more dilute and leached to the out limits of the wet zone to make
the
use of saline water more practical,( Jensen, 1983).
6- Weeds growth is reduced because of the limited wet soil surface,
( Lateif, etal., 1988).
7- Use of trickle irrigation is practical even in fields that have 5-6%
slope
without erosion (Khalil, 1998 ).
8- Trickle irrigation needs no leveling , no drainage and no other
field
operations like ridging.
9- Fertilizers and chemicals can be injected into the irrigation water
causing a uniform distribution at the root zone (Al-Amoud,1997).
10- Bacteria, Fungi and other pests and diseases that depend on moist
environment are reduced, as the above ground plant parts are
normally
completely dry. (Schwab, etal., 1993).
11- Landscape is the area where drip irrigation is experienced it
would
widely suit many landscape situations, balancing the high and
rapidly
rising cost of water and pumping energy.
12- The environment is kept sound by not allowing chemicals
(fertilizers,
pesticides and herbicides) to run deep and penetrate into the soil
to
affect ground water.
2.8 Disadvantages of drip irrigation:
1- The major disadvantage of the system is its high capital or initial
cost,
(Michael, 1999).
2- Clogging of emitters by biological, chemical and physical matters.
3- Frequent application of water leach the salts out to the limit of the
wetted zone, if system stops supplying water, the salts may enter
to the
root of the plant causing wilting or poisoning the plant,
(Abd elazeem, 1997).
4- Shallow roots due to the limited wet zone. The field needs
frequent
irrigation and in case of trees they are liable to tilt in the windward
direction and may be uprooted.
2.9 Types of drip irrigation systems:
2.9.1 Bubbler irrigation:
Application of water as a small fountain. It is a combination of
surface and drip irrigation that needs a small basin, because the
discharge is too high to infiltrate, about 20 to 225 liters per hour. It
is
usually used for orchards and big trees ( Ismail, 2001)
2.9.2 Drip (trickle) irrigation
Delivering slow frequent applications of water in discharge
points
or line source with a discharge of 2-100 liter / hour. Trickle
irrigation
can be on the surface or sub surface The latter is preferred in light
soils.
2.9.3 Micro-Sprayers:
Small applications are used to spray irrigation water to cover an
area
of 1-10 square meters. They are also called aerosol emitters,
foggers,
micro sprayers, or miniatures sprinklers. (Michel, 1990)
2.9.4 Mobile Drip Irrigation System:
Combine the benefits of trickle and sprinkler irrigation systems.
Using linear system or center pivot replacing the sprinkler with
laterals
finished with emitters (Al-Amoud, 1997).
2.10 System components:
The components required for trickle systems are generally more
complicated than those for other applications systems due to the need to
filter the water supply and to maintain a specific pressure distribution
throughout the system. The components of a typical trickle system are
shown in
Fig. 2.1. The system can be divided into the mainline, submain, and lateral.
The mainline has a pump to pressurize the system and possibly a
chemical
injector to conveniently apply nutrients through the distribution system.
Primary filter is used to screen the largest particles out of the system .
Primary pressure gauges on either side of the filter are used to evaluate
when pressure drop across the filter is high enough to required backflushing.
The final components on the main line are control valve, pressure and flow
regulation.
The submain line has a secondary filter for finer particles and a solenoid
valve to aid in system automation. A pressure regulator is required on this
line to keep the system operating within the close tolerances of discharge
necessary for the water balance. Secondary pressure gauges are used to
verify the operating pressure. Flush valves are shown at the end of the
submain line to periodically clear accumulated debris from the line.
Lateral lines are shown coming off the submains. The lateral distributes
water to the emitters which deliver water directly to the root zone.
2.10.1 Pump:
The irrigation pumps force the water to create matching pressure for
the
system designed. Centrifugal pumps are usually used in irrigation. Its
mechanism uses an impeller to spin water rapidly in a housing. This type
of
pump must have water in the case so it has a small valve to hold water.
Centrifugal pumps are divided into End–Suction Centrifugal the most
common pump in drip systems, Submersible usually shaped like a long
cylinder to match the works inside the wells and Turbine pumps which are
mounted under the water and would be attached by a shaft to a motor
raised
above the water. Turbine pumps are the most efficient type of pumps that
can
be used in wells or lakes.
2.10.2 Control head
The head works consist of the main control station and may consist
of the pump, filters, pressure regulating, valves, flow regulating valves,
control valves, water meters, pressure gauge, automatic controllers, or
time clocks, and chemical injection equipment, (Jensen,1993) Plate 2.1
Plate 2.1Control head with aventuri tube
2.10.3 Valves
A valve is a device to control the flow of water. Valves are divided
into:
a- Emergency shutoff valves which should be located at the way of the
water to the system. The commonly used are gate valves, ball valves,
disc valves, or butter fly valves.
b- Control valves can be operated manually, electrically, hydraulically,
and automatically. Material used for valves is brass or plastic, (Plate
2.1).
Plate 2.2 Control valve
2.10.4 Backflow preventer:
The backflow preventer is located before the pump to prevent the flow
back
of irrigation water not to contaminate the source with chemicals and
fertilizer
2.10.5 Pressure and flow regulators:
Installed in the mainline to save the system from increasing the
pressure and regulate the flow.
2.10.6 Filters:
The filter is an essential component of the drip system its aim to
minimize
or prevent emitter clogging, the type of filtration needed depends on water
quality and on emitter type. (Gilbert, etal., 1979,1981; Ravina, etal.,1992).
Each
type of filter is effective for a particular particle size and type of suspended
material, for a specific flow rate, and has a characteristic capacity for
sediment
collection. (Dasberg, etal., 1999), (Plate 2.3).
Filters can be classified into:
a-Screen filters:
The most common filter. It is excellent for removing hard particulates,
but is
not so good at removing organic materials.
b- Cartridge filters:
Most of the cartridge filters contain a paper filter which works like a
screen
filter. It removes organic materials well. Most of them are replaceable
when dirty.
c- Media filters:
Media filter cleans water by forcing it through a container filled with a
small sharp edged media, in most cases the media is uniform sized crushed
sand.
d- Disc filter:
Disc filters are a cross between screen and media filters with many
of the advantage of both. A disc filter is good at removing particulates like
sand
and organic materials.
Media Filter
Cartridge Filter
Disc filter
Plate 2.3 shows three types of drip irrigation filters
e- Centrifugal filters:
Also known as 'sand separation', they are primary for removing
particulates such as sand from water where a lot of sand is present in
the water (Stryker, 2001).
Table 2.1 gives a summary of recommendation on the types of filters to be
used under different condition of water quality. On the other hand Table
2.2exhibits classification of screen and particle size as adopted from
Nakayama,
(1986) and Cuenca, (1989).
Table 2.1 Filters types recommendations
Water source
Filter
Municipal water system
Screen filter, centrifugal filter, or disk
filter
Well
Screen filter, centrifugal filter, or disk
filter
River or creak
Disk filter, media filter, screen filter, and
centrifugal filter.
Pond or lake
disk filter, Media filter, screen filter, and
centrifugal filter.
Spring or Artesian well
Screen filter, centrifugal filter, or disk
filter
Organic
material
in
disk filter, media filter, screen filter, and
water
centrifugal filter.
Sand in water
Screen filter, centrifugal filter, or disk
filter
Source: Stryker, (2001).
Table 2.2 Classification of screen and particle size
Equivalent
Particle
Equivalent
diameter
designation
diameter
(microns)
(microns)
16
1180
Coarse sand
> 1000
20
850
Medium sand
250-500
30
600
Very fine sand
50-250
40
425
Silt
2-50
100
150
Clay
<2
140
106
Bacteria
0.4-2
170
90
Virus
< 0.4
200
75
270
53
400
38
Adopted from Nakayama (1986), Cuenca, (1989).
2.11 Fertilizing methods
The fertilizing system used to add chemicals, (nutrients,
herbicides, or
pesticides) to the irrigation water is considered an integral part of the
drip
system. The process of adding fertilizer with irrigation water is
called
"Fertigaition" The solubility of fertilizer must be known, and the
system or
advice must be calibrated. The following equation stated by Ismail,
( 2002) can be used for calibration:
(2.1)
Qf =
Where:
Fr × A
..............................................................
T × Tf × Fc
Qf = The rate of fertilizers injection (l /h)
Fr = Fertilizer required dose (Kg /fed)
A = Area (fed)
T = Irrigation set time (h)
Tf = Fertigaition time (not more than 50% of T)
Fc = Fertilizer concentration (Kg / l)
There are various ways to performing fertigaition:
- Venturi tube principle:
A constriction in the main water flow pipe increases the water flow
velocity thereby causing a pressure differential (vaccum) which is
sufficient to suck fertilizer solution from an open reservoir into the
water
system.
- Fertilizer tank (By-pass system):
The method employs a tank into which dry or liquid fertilizer is
placed, the tank is connected to the main irrigation line by means of a
by
pass so that some of the irrigation water flows through the tank and
dilutes
the fertilizer solution. The concentration of fertilizer in the tank
degreases gradually, until it reaches the level of irrigation water .
- Injection system:
With this method a pump is used to inject fertilizer solution into the
irrigation line. The solution is normally pumped from an
unpressurized
reservoir.
2.12 Main and submain lines
The main and submain lines are usually placed underground and
they
supply water to the laterals. Normally they are made of polyvinylchloride
(PVC) pipes or polyethylene (PE). The (PVC) pipes are divided into
low and high pressure categories, based on pipe diameter and design
operating pressure, rarely asbestos and cement pipes are used for the
main
lines.
2.13 Laterals:
Laterals are the tubes on which the emitters are mounted or within
which they are insert or integrated. They are usually made of
polyethylene with the following features: flexibility, non corrosivity,
resistivity to solar radiation and the effect of temperature fluctuations
,
ease in manipulation, and generally, black in color (Recently, green
or
brown colored). Laterals usually have inner diameter in the range of
12-32mm, and wall thickness made to withstand pressure up to 4-6
bar
depending on need, ( Dasberg, etal., 1999).
2.14 Manifolds:
A manifolds is the part of pipe net work between the main and the
laterals, manifolds also called trenches. Depth of trenches depends on
the depth of the main lines, PVC pipes must be at least 45 cm (18")
deep
measure from the top of the pipe, so trench goes to 50 cm (20") deep
under the ground surface, (Plate 2.4)
Plate 2.4 Manifolds
2.15 Fittings:
Fittings are the standard name used for various parts which attach pipes
together, as shown
in Plate 2.3 crosses, bushings, couplings, elbows,
reducers,
tees and adapters male or female are fittings. It may be threaded, barbed or
welded to pipe. Usually glue or cement is used on plastic fittings, but
threaded
plastic fittings are tightened with hand only.
End cap
Elbow
Adapter
Tee
Grommets
Reducer
Connectors
Plate 2.5 Shows some important drip irrigation fittings
2.16: Emission point:
The point on or close to the ground surface, where emitters discharge
water are
emission point According to the discharge spacing, when spacing is 1 meter
or more it is called point-source, and when its less than 1 meter it is a
line–source.
Plate 2.6 Emission point, in-line dripper
2.16.1 Line- source tubing:
There are three types of line –source tubing:
a- Single-chamber tubing: It is a small diameter hose ( less than 25mm )
that has
orifice punched or complex emitters or inserted at intervals of 0.6m or less.
b- Double-chamber tubing: This is a small diameter hose ( less than 25mm )
that
has both a main and an auxiliary bore separated by a single wall. Widely
spaced
inner orifice punched in the separated wall, for each inner orifice 3 to 6
exit
orifices are punched at intervals of 1.5 to 0.6 meter in the outer wall of the
auxiliary bore.
c- Porous-wall tubing: It is a small diameter hose ( less than 25mm ) that has
a
uniformly porous wall The pores are at capillary size and ooze water when
under pressure.
2.16.2 Emitters
The emitter is a device used to dissipate the pressure and to discharge
water at a constant rate at many points along a lateral. It is the main
component of the drip irrigation system and determines it
characteristics.
Emitters have many types and may be classified according to the
flowing
criteria; flow rate, form of pressure dissipation and details of
construction and incorporation in the lateral, (Karmeli, 1977;
Dasberg,
etal., 1999), (Plate 2.6).
a- Flow rate and its variation:
Each emitter has a certain design flow rate, by its mean at normal
operating pressure. The coefficient of manufacturing variation
(CV) may vary from 0.02 for spiral long path emitters to 0.4 for
porous pipe, and has a critical effect on the irrigation efficiency of
the system. The flow rate is affected by pressure, temperature and
obviously by clogging.
b- Form of pressure dissipation:
The operating pressure of most emitters is in the range of 0.1 –
0.2 MPa. This pressure is dissipated in the emitter pathway and
reaches the outlet at atmospheric pressure, by directing water
flow through long narrow path (long–path emitters), through
small opening (orifices emitters) or through labyrinth to create a
turbulent flow.
c- Discharge regulation by pressure compensating:
Some emitters are equipped with special constructed membrane
or diaphragm to ensure a constant pressure over a wide range of
pressures. These emitters are usually more expensive but allow
very long laterals (more than 500 m for emitters of 1.6 (l/h) at 1
m distance between emitters), (Dasberg etal., 1999).
2.17 Hydraulics of emitters:
The relation between emitter discharge and operating pressure is
dependent on flow regime, which is determined by the dimensionless
Reynold's number (RN).
2.17.1 Reynold's number(RN):
RN = VD / (1000v) ...................................................... .. (2.2)
Where :
Rn = Reynold's number, dimensionless
V = flow velocity, m /sec
D = emitter diameter, mm
v = kinematics viscosity of water, m2 /sec
The flow regime is divided into the following types due to Rn:
a – Laminar flow (RN < 2000)
b – Turbulent flow (RN > 4500)
c – Unstable flow regime (2000 < RN > 4500)
The friction factor (f) for laminar flow is, (f) = 64 / RN ........ . (2.3)
The friction factor (f) for turbulent flow is, (f) = 0.316 / RN0.25
...(2.4)
2.17.2 Emitter discharge exponent:
According to Hillel, (1987) the discharge for most trickle
irrigation
emitters or sprays with fixed or unfixed cross section can be given by:
Q = Kd × H
X
.......................................................................
...(2.5)
Where :
Q = Emitter flow rate or discharge (l /h)
Kd = Discharge coefficient (empirical factor)
H = Working head pressure at the emitter
X
= Emitter discharge exponent
In order to find the value of (X) the expression used is :
X
= Log (Q2 / Q1) ................................................ (2.6)
Log (H2 / H1)
Where :
Q1, Q2 are discharge; H1, H2 are pressure at two known
points.
(Kd) is computed by compensating (X) value in equation (2.4)
The values of (X) should range from 0 for pressure compensating
emitter
to 1 for an emitter in laminar flow regime. The discharge exponent
should
equal about 0.5 for emitter operating in turbulent flow regime,
(Cuenca, 1989).
2.17.3 Emitters manufacturing coefficient of variation( CV):
It is impossible to manufacture the emitters exactly alike , because
of
the critical dimensions of emitter passage .So the small difference may
cause significant variation .The manufacturing coefficient of variation
for
emitter (CV) can be calculated from the discharge data of a sample of
at
least 50 emitters by the following equation:
CV =
………(2.7)
√
(q1
2
+ q2
2
+ ….. qn
2
– nqa2 ) / (n-1)
qa
which is
(2.8)
Where :
CV = sd / q a
………………
CV = coefficient of manufacturing variation
n = number of emitters in the sample
qa = average emitter discharge rate for the sample
( q1 + q2 … + qn ) / n , l/h.
sd = estimated standard deviation of discharge rates of the
population (l/h)
Table 2.3 Classification of emitter coefficient of manufacturing variation
(CV)
Classification
Excellent
Drip or spray emitters
Line source tubing
CV < 0.05
CV < 0.1
Average
0.05 < CV < 0.07
0.1 < CV < 0.2
Marginal
0.07 < CV < 0.11
Poor
0. 1 < CV 0.15
Unacceptable
0.15 < CV
0.2 < CV < 0.3
0.3 < CV
Source: Keller, etal., (1990 )
This has basically been adopted in the Engineering Practice Standard :
ASAE EP405.1 ( Keller, etal., 1990 )
2.18 Determining of the allowable pressure difference :
In order to conduct the allowable pressure difference there are two
techniques.
(1)
The American Society for Agric. Engineers (ASAE) which
suggests
that the allowable discharge variation is ± 10 % , and with the use
of
equation (2.4) the allowable pressure difference (∆P) is computed
by
equation (2.8).
∆ P = 1 dq × H ……………………………………… .(2.9)
X
q
Where:
∆ P = allowable pressure difference
dq = discharge variation.
q = Emitter discharge (l/h).
X
= Emitter exponent.
H = Operating pressure.
(2) Design uniformity technique
EU = 1-
1.27CV
qmin
…(2.10)
√N
………………………
qav
Pmin / Pav = (qmin / qav)1/x
………………………… (2.11)
Where:
CV = coefficient of manufacturing variation.
N = number of emitters.
EU = field test emission uniformity %
qav = average or design emitter discharge, (l/h).
qmin = average rate of discharge of the lowest one-fourth of the
field
data emitter discharge readings, l/h
Pmin = lowest calculated pressure.(m)
Pav = operating pressure (m).
Traditional way to carry out (∆ P) is equation (2.11):
∆ P = 2 (hav –hmin) …………………………….. (2.12)
Where:
hav = operating pressure (m).
hmin
= lowest calculated pressure (m) from equation
(2.10)
2.19 Laterals hydraulics:
Head losses along laterals (hf) of drip irrigation systems strongly
affect the available head at emitter nozzles. Consequently, discharge is
significantly affected when conventional non-compensating emitters
are
used. These losses are frequently estimated by adding frictional losses,
(Juana, etal., 2002)
2.19.1 Blasius equation calculates friction factor (f) in smooth pipes
as
follows:
f
=
0.316
RNo.25
/
........................………………………(2.3)
The Darcy- Weisbach equation is used to calculate laterals
hydraulics
(Cuenca , 1990.) .The Darcy–Weisbach (f) factor can be used to
calculate friction losses over a range of Reylond's number in both
laminar
and turbulent flow regimes. The Darcy–Weisbach equation calculates
friction losses in a length of pipe with known flow and pipe diameter.
(Stryker, 2001).
2.19.2 Darcy–Weisbach equation:
hf = 6.377 fL Q2 /D5 …… .... ...... .....
…….(2.13)
Where :
hf = friction losses along lateral, m.
L = lateral length , m.
........ ……
Q = total lateral flow rate , l/h.
D = lateral diameter , mm
f = Darcy–Weisbach friction factor .
2.19.3 Christensen's friction factor:
To covert from pressure losses in fully flowing pipe to pressure
losses
in a pipe in regular outlets such as drip irrigation, (A.B.E. 2001)
hac= hf F ………
……
…… ..... ......
.......
.…
….(2.14)
Where :
hac = actual pressure losses in the pipe.
F = Christensen's friction factor
Christensen's friction factor (F) is given by the equation
1 +
M+1
F=
1
+
2N
( M – 1 )0.5 ....... ........ ...(2.15)
6N2
Where:
N = number of outlets.
M =exponent in Hazen–Williams equation
2.19.4 Hazen–Williams equation:
(2.16)
hf = KL [Q/C1.852]
………
………
…… … ....
D4.87
Where : K = conversion constant, 1.21×1010
L = length , m .
Q = flow rate l/sec.
C = Hazen-Williams coefficient, C =140 for drip and PVC
pipe
D = pipe diameter, mm.
2.20 Uniformity of drip irrigation :
Emission uniformity EU% is a measure of emissions from all the
emission points within an entire trickle irrigation system.
(Keller,etal.1990).
EU% = 100 qn / qa …………………………..(2.17)
Where :
EU% = field test emission uniformity %
qn
= average rate of discharge of the lowest one-fourth of the
field
data emitter discharge readings, (l/h)
qa = average discharge rate of all the emitters checked in the field
(l/h)
EU can also be given by the equation (2.10)
2.21 Soil moisture content :
Generally plant growth depends mainly on the soil moisture
between
field capacity and permanent wilting point which is known as
available
soil moisture .
2.21.1 Field capacity ( F.C.):
The field capacity (F.C.) is the water content after drainage of the
gravitational water has become slow and the water content has become
relatively stable .This situation usually exists one to three days after
rain or irrigation. Field capacity content depends on soil texture. In
this
situation soil moisture tension ranges between 0.1 to 0.7 bar,
(Khalil,1998).
2.21.2 Permanent wilting point (P.W.P) :
Michael (1978) mentioned that permanent wilting point is the soil
moisture content at which plants can no longer obtain enough moisture
to meet transpiration requirement, it is at moisture tension of about 15
bar.
2.21.3 Available water :
Available water is the moisture content between field capacity and
permanent wilting point. Available water can be expressed as
percentage
moisture, percentage volume or depth.
2.22 Measurement of soil moisture content:
Soil moisture is measured directly by using the gravimetric method
or
indirectly by measuring soil water potential using certain devices such
as
tensiometers, electrical resistance blocks, neutron scattering and
magnetic
field resistance.
2.23 Drip and plant rooting :
In studies of tomato root distribution under drip irrigation, 90% of
the
roots were found to concentrate at the upper half of the roots depth,
and
at 50 to 150 mm of the emission point of the horizontal axis
(Al Amoud, 1997).
2.24 Drip irrigation system design :
Trickle irrigation designing, is usually done by a first guess for an
emitter spacing acceptable for the selected crops - and flow rate
matching the soil texture. Then the crop water requirement is
computed at
the maximum daily crop requirement in the middle of summer. Then
to
calculate the pump power and discharge, filters types and capacities,
main,
submain and laterals lines hydraulics.
2.25 Emitter spacing:
Spacing between emitters depends on the volume of soil wetted per a
single emitter. Table 2.4 shows the suggested emitter spacing
according to
soil texture, (Khalil, 1998).
Table 2.4 Suggested emitters spacing according to type of soil.
Distance between emitters m
Emitter
discharge l/h Coarse texture Medium texture Fine texture
> 1.5
0.2
0.5
0.9
2
0.3
0.7
1.0
4
0.6
1.0
1.3
8
1.0
1.3
1.7
12<
1.3
1.6
2.0
Source: Khalil, (1998)
Keller, etal., (1991) proposed the following equation to calculate the
spacing between emitters
Se ≤ 0.8 dw …… …… ..... ....... ..... ...... ..... ( 2.18)
Where :
Se =emitter spacing
dw = soil surface wetted by a single emitter
2.26 Number of emitters per plant:
James, (1988). suggested the following equation to calculate the
number
of emitters per plant.
N = (1000 × P × S × L)
dw × Se
…………………………… (2.19)
Where :
N = number of emitters per plant.
dw = maximum diameter of wetted area caused by a single
emitter.
Se = spacing between emitters (cm)
P = percentage of wetted area (decimal)
S = spacing between emission points (m)
L = spacing between plant rows (m)
2.27 Crop water requirement (CWR):
Crop water requirement under trickle irrigation systems is different
from crop water requirement under surface and sprinkler irrigation
systems
because the field wetted area is reduced, resulting in less evaporation
from
the soil surface.
Most methods of estimating crop water requirement provide
estimates of
evapotranspiration which probably contain a significant soil
evaporation
component (Doorenbos and Pruitt, 1977; Gangopadhayaya , etal., 1966
and
Jensen, 1974)
Crop water requirements are usually expressed in units of water
volume
per unit land area (m3 /ha), depth per unit time (mm/day), (Jensen,
1983).
Crop water requirement, which is equal to crop evapotranspiration can
be
calculated according to the following equation :
ETc = ETo × Kc ……………………………(2.20)
Where :
ETc = Crop Evapotranspiration (mm/day).
ETo = Reference crop Evapotranspiration (mm/day).
Kc = Crop coefficient
Reference crop evapotranspiration (ETo) can be calculated according
to the Penman-Monteith formulas as stated by Ismail, ( 2002).
ETo =
Where :
ETo
∆ . Rn + ɤ (900/T + 273) U2 (es – ea) ……… (2.21)
∆ + ɤ (1+ 0.34 U2)
=
Reference crop evapotranspiration.
Net radiation at crop surface (Mjm-2 day -1 ).
Rn
=
T
= Average temperature at 2 m high .
(es – ea) = Vapor pressure deficit for measurement at 2 m
high.
= Wind speed at 2 m high (ms-1).
U2
The following formula was used to adjust the wind speed data from 20
m
to standard height of 2 m, as stated by Ismail (2002)
U2
.....(2.22)
=
Uz
In
4. 85
. .....
Zm – 0.08
0.015
Where :
Uz = mean wind speed measured at height (z) ( m/sec) .
U2 = mean wind speed measured at height 2m (m/sec) .
Zm = height at which wind speed is measured (m).
When there is no enough data to calculate U2 , it is possible to use the
International average wind speed (1+3) / 2 = 2m/ sec .
∆
= Slope of vapor pressure curve (K Pa C°).
ɤ
= Psychometric constant (K Pa C°).
900
= Coefficient for reference crop (Kj Kg day -1).
0.34
1
=
Wind coefficient for the reference crop (Sm-
)
Reference crop evapotranspiration (ETo) can also be calculated by the
the Penman-Monteith formulas (2.23) as stated by Ismail, ( 2002).
0.408 ∆(Rn – G) + ɤ (900/T + 273)U2 (es – ea) ……
ETo =
(2.23)
∆ + ɤ (1+ 0.34U2
Where :
G = Soil heat flux(Mj m-2 day-1).
Soil heat flux(Mj m-2 day-1) (G) may be uncounted if the period is less
than 10 days. And it can be calculate according to the equation
G moth = 0.14 (T month – T month-1) ………………......... (2.24)
Where :
T month = Average temperature for the mentioned month (C°).
T month-1 = Average temperature for the month before (C°).
ea = es × relative humidity as a friction (Ismail, 2001)... (2.25)
2.28 The net crop water requirement (NCWR):
The net crop water requirement is the amount of water needed to
supplement the effective rainfall in the crop root zone. Effective
rainfall is
the portion of rainfall that contributes to meet the evapotranspiration
requirement of
crop, (Hershfield.1964) In order to determine the
effective
rainfall four different equations can be used as suggested by
Smith, , etal., (1991) and FAO(1992).
1-Fixed percent of rainfall:
pe = a × ptot ……………………. (2.26)
Where :
a = fixed percentage that accounts for losses from rain fall
and
deep percolation.
pe = effective rainfall (mm /month).
ptot = total rainfall in given month (mm /month).
2 -Dependable rainfall:
pe = 0.6 × ptot – 10 ………………………… (2.27)
(for ptot ≤ 70 mm )
pe = 0.8 × ptot – 24 ………………………….(2.28)
(for pe ≥ 70 mm)
where:
pe and ptot are as defined before.
3 –Empirical formula:
pe = a × ptot + b ………………….(2.29)
(for ptot ≤ z mm)
pe = c × ptot + d …………………(2.30)
(for ptot ≥ z mm)
4 –USDA soil conservation services method:
pe = ptot (125 – 0.2ptot) /125 …………..(2.31)
(for ptot ≤ 250mm)
pe = 125+ 0.1ptot ………………………(2.32)
(for ptot ≥ 250mm )
Where :
Pe and ptot = are as defined before.
a,b,c, d
z
= are correlation coefficients.
= is an empirical defined value of target rainfall
characterizing the study area.
2.29 Gross irrigation requirement (Ig):
Gross irrigation is the depth or volume of irrigation water
requirement
over the whole cropped area excluding contribution from other sources
,
plus water loss or operational wastes. Verneiren and Gobling (1980)
suggested the following relation:
Ig =In + Lr …………………………….. (2.33)
Ea
Where:
Ig = gross irrigation requirement (L)
In = net water requirement (L)
Ea = application efficiency (decimal)
Lr = extra amount of water needed for leaching (L)
2.30 Irrigation efficiency for drip systems:
Irrigation efficiency is defined as the ratio of the quantity of water
put into the crop root zone and utilized by the growing crops
to the quantity delivered to the field (Bos and Nugteren, 1990). The
overall application efficiency of drip irrigation (Ea) may be defined as
stated by Vermeiren and Gobling, (1990) as follows:
Ea = Ks ×Eu ……… ……… ………… ………
………..
(2.34)
Where:
Ks = ratio between water stored and that diverted from the field,
expresses the water storage efficiency of the soil. It takes into
account
unavoidable deep percolation as well as other losses. Table 2.5
shows
values of Ks for different soil types.
Eu = coefficient which reflects the uniformity of application.
Table (2.5) Water storage efficiency (Ks %)
Type of soil
Water storage efficiency (Ks
%)
Clay
100
Mixed
silt,
clay
and 95
loamy
Loamy
90
Sandy
87
Source: Elghundi, (2000)
2.31 Depth of water to be applied by irrigation:
It is the amount of irrigation water required to bring the soil
moisture
content level in the effective root zone to filed capacity .Vermeiren
and
Gobling (1980), proposed an equation to calculate the depth
considering
that only part of the soil volume is to be wetted by drip irrigation a
follows:
D = 10(FC - PWP)×d× Z ×P ……………….(2.35)
Where:
D
=
maximum amount (depth) of water to be applied
(mm)
FC
= filed capacity (cm/m)
PWP = permanent wilting point (cm/m)
d = the root zone depth (m)
Z =
the moisture depletion percentage allowed or desired
(decimal)
P = the volume of soil wetted as a percentage of total volume
(decimal)
2.32 Irrigation set time for drip:
It is the time required to apply an irrigation .Vermeiren and
Gobling
(1980) stated that the estimation of the maximum time of application
is based on providing water for plant when it can use it .
T = ETc × Se ×SL × K … ………… ……….. (2.36)
E ×Q
Where:
T
= Irrigation set time (h).
ETc = crop evapotranspiration (mm / day).
Se = emitter spacing along the lateral (m).
SL = lateral spacing (m).
E = emitter efficiency (%).
Q = emitter discharge (1/h).
K = constant (in metric system = 1).
2.33 Irrigation frequency:
It is the number of days between irrigations during periods
without
rainfall. Goldberg, et al , (1971) stated that on most soil such as loam
and clay loam there is much experimental evidence showing that
irrigation interval of 2 – 3 days provides an optimum moisture
regime.
2.34 System capacity:
Capacity depends on the irrigation application rate, time of
irrigation,
and interval between irrigations. Wu (1975) suggested an equation to
calculate the system capacity as follows:
Q = (Ig × A) ………………………. (2.37)
T
Where:
Q = drip irrigation system capacity (m³/h).
Ig = gross irrigation water requirement (m).
A = the global area to be irrigated (m²).
T = irrigation time (h)
2.35 Squash:
The squash plant (Cucurbita pepo), family (Cucuribitceae), has
large
rough leaves ,and a crumbly stem. The total root growth of the
squash
plant resembles the root growth of other pumpkins to an extent, as
its
secondary roots spread within the 30 cm, below the soil surface.
Sowing
date for the Summer season is during the second half of February upto
the first half of April. And for the Winter season, from September to
November. Crop collection starts after forty days after planting
during the
Summer season and after fifty days during the Winter season.
The parameters measured for comparing the results were:
1- Yield and yield components which include.
a- Yield (Kg / line)
b- Efficiency of water use (Kg / m3)
2- Plant diameter (cm)
3- Plant height (cm)
2.36 Field practices of crop production under different irrigation
systems:
Shehata and Bakeer (1995) studied the effect of irrigation
systems on
potato crop in sandy soil, under Egypt climatic conditions. The study
gives a comparison between surface, sprinkler, and drip irrigation,
systems, as shown in Table 2.6. On the other hand AL-Amoud, (1998)
reported the production of some crops under different irrigation
systems, as
shown in Table 2.7
Table 2.6 A comparison between surface, sprinkler, and drip irrigation
systems.
Irrigation system
Case study
Amount of water applied
Surface
Sprinkler Drip
6981
6064
4564
5.159
7.525
8.83 8
1.24
1.94
(m3 /fed.)
Yield
(ton /fed.)
Irrigation water use efficiency (Kg 0.74
/m3)
Source: Khalil (1998)
Table 2.7 A comparison between production of some crops under
different irrigation systems.
Irrigation
Crop yield
system
(ton / ha)
Sac / ha
Kg
tree
Beans potato Pepper tomato
Cucumbe
Onion
Apple
712
37.5
r
Drip
1.636
36.50
0
5.42
13.64
11.60
/
Furrow
1.432
_
4.20
10.72
10.64
472
_
sprinkler
0.890
32.70
_
_
_
668
16.4
0
Source: AL-Amoud, (1998 )
Water source
Pump
Pressure gauges
Water filter
Source: Hillel, (1987)
Fig 2.1drip irrigation components
Main line
Main gate valve
Pressure regulator
Flow meter
Fertilizer injector
Submain line
Electric controls
Solenoid valve
Laterals
Emitters
Zone two
Zone one
Sub main unit
CHAPTER THREE
MATERIALS AND METHODS
3.1 Site description and experimental layout:
The experiment was conducted in the Demonstration Farm of the
Faculty of Agriculture, University of Khartoum, Shambat at latitude
15° 36' N, longitude 32° 32' E and altitude 380 m above mean sea
level.
The climate of the area is tropical semi arid. It is characterized by
low
relative humidity, with mean daily maximum and minimum
temperatures
of about 36° C and 21° C respectively. The annual rainfall is about
158
mm
mainly
during
July,
August
and
September
(Sudan
Meteorological
Department 1951- 1980).
The soil of the experimental field is heavy clay with percentage
ranging between 65% in the top 15 cm and 55% in the 100-140 cm
profile. The soil reaction is moderately alkaline with a pH ranging
from
7to 8, (Saeed, 1968). The infiltration rate is low and has been
estimated to
be about 20mm /h in the first two hours and 5mm / h after 10 hours
(Ferguson, 1970).
An area of 1/2 feddan was used for conducting a randomized
block
experimental design (Figs. 3.1 and 3.2)
3.2 Land preparation:
The experimental field was ploughed with a standard integral
mounted
disk plough at a depth of about 0.25 m. The land was then left for
about
two weeks, then leveled with a general purpose blade. Ridging was
done
at a spacing of 0.7 m with a general purpose ridger. However when
planting squash a ridge between every two ridge was left with out
planting to give a spacing of 1.40 m in accordance with the standard
practice for growing squash as recommended by the State Ministry of
Agriculture, Khartoum.
3.3 Drip irrigation system description:
3.3.1 Pump unit:
An Indian make electric 2 inches centrifugal pump, (Model 2kd-20)
was
used to draw irrigation water from the main line of Shambat
domestic
water supply system. The pump specifications, are, maximum
pressure
head-16 m;. maximum discharge 420 l/h; maximum suction head
9 m; r.p.m. 2850/min and power is 1.1 kw
3.3.2 Control unit includes:
a- An emergency shut off valve is located before the pump.
b- Control valve located after the pump.
c- Three pressure gauges two 5 bar each and one 1 bar.
d- Filter, disk type (Model Drop ) Turkish make with maximum
pressure of 8 bar .Plate 3.1
Plate 3.1 Disc filter
e- Vacuum breaker .
f- Pressure regulator
j- Venturi tube principle
3.3.3 The main line:
A 30 m, 5cm diameter polyvinyl chloride (PVC), main line was
buried below ground surface at a depth of 50 cm meters.
3.3.4 Submain line:
Two PVC submain pipes were connected directly to the main line
each pipe was 16 meter in length and 2.5cm in diameter. The
submains
were also buried at 50 cm below ground surface.
3.3.5 The lateral lines:
The 13 mm diameter lateral pipes, were made of black linear,
low densi Poly ethylene (LLDPE). There were two types of the
emitters
(built-in GR. and built-on Turbo-Key). The laterals were connected
to
the submain at 0.75 m spacing and 140 cm spacing for squash.
3.3.6 Emitters:
The built-in, G.R. Eurodrop emitter rated at 3.8 l/h, are Egyptian
make, and the Turbo Key on-line emitter rated at 4 l/h, are Saudi
Arabian
make. Plates 3.2 and 3.3 show built-in and built-on emitter
respectively.
The emitters specifications are show in Table 3.1
Plate 3.2 Built-in (GR) tube
Plate 3.3 Built-on (Turbo-Key) emitter
Table 3.1 Emitters specifications
Type
Model
Country
of Discharge
origin
In-line
GR
Egypt
3.8
On-
Turbo-
K. Arabia Saudi
4.0
line
Key
3.4 Furrow method:
The water was drawn by the same pump to supply the control lines
for the second part of the experiment, through a 13 mm inside
diameter
pipe in which the discharge (flow rate) was calibrated volumetrically.
3.5 The squash data collection:
The squash crop was paused at 50 cm between plants,140 cm
between
rows,
in
accordance
with
the
standard
practice
recommended by
the State Ministry of Agriculture, Khartoum.
The variety used was Exandrany squash, with 100 % purity, and 86 %
for germination rate.
The parameters measured for the crop consisted of the following:
- Yield and yield components (Kg/ line)
- Efficiency of water use (Kg/m3)
- Plant diameter to compute reduction factor (Kr.) (cm)
- Plant height. (cm)
3.6 Measurements:
3.6.1 Measurement of discharge:
Volumetric calibration of the emitters was made with the help of a
graduated cylinder and a stop watch and was replicated at least three
times for each emitter. This application was done every 10 meters
along
the laterals lines.
3.6.2 Measurement of the pressure:
Two gauges type Bourdon 5 bar each, were used in the head unit
and one, a bar divided to 10 sections for measuring laterals pressure.
Plate 3.4
Plate 3.4 Pressure gauge (one bar capacity)
3.6.3 Measurement of the soil moisture content:
Soil moisture content was determined gravimetrically before and
after
each irrigation using the relationship as follows:
Moisture content % =
(mass of wet sample – mass of oven dry sample )x100
mass of oven dry sample
Five samples were randomly selected from depths 0-10,10-20,
20-30,
30- 40 and 40-50 cm. The soil moisture content was then converted
to
moisture content on volume basis by multiplying it by the soil bulk
density.
3.6.4 Measurement of the wetted soil depth:
The depth of wetted soil under the emitter was measured using a
graduated steel penetrometer.
3.7 Experimental procedure:
The experiment was conducted in two parts. The first one was
concerned with some hydraulic studies. Three lateral lines having the
lengths of 40, 60, 80 meters, replicated 3 times Fig. 3.1 to evaluate the
effect of laterals length on the distribution of discharge, pressure and
ultimately emission uniformity.
The second part of the experiment was conducted for the crop
water requirement studies using drip irrigation system. This part was
conducted during two seasons (Feb. to April) and (Oct. to Dec.). Forty
m
long laterals were connected to the submain at 140 cm spacing to
match the
squash spacing. Two types of emitters (built-in and built-on) were
used
and laterals were placed at two positions: above soil surface , and 10
cm
below soil surface, while the furrow system was used as a control. The
treatments were replicated three times, as shown in Fig 3.2.
The data collected included soil moisture content on volume basis,
water requirement for squash, drip
irrigation system emission
uniformity
and efficiency.
CHAPTER FOUR
RESULTS AND DISCUSSION
4.1 Emitters discharge:
Table 4.1 shows the results of average discharge for two
different
working pressures and it appears that the discharge increases as
pressure increases.(App. 1)
Table 4.1Emitters discharge
Type of emitters
Pressure (bar)
0.5
1.0
Discharge (l/h)
Built-in tube
2.95
3.84
Built-on line
2.97
4.01
4.2 Emitters exponent (X) and discharge coefficient (Kd):
Table 4.2 shows the value of the emitter discharge exponent
(X)
and
the discharge coefficient (Kd) of equations (2.5) and (2.6). It shows also
the discharge-pressure co-relation for the two types of emitters used.
(App.2)
Table 4.2 Emitters discharge exponent (X) and the discharge coefficient
(Kd)
Co-relation
(r2)
Type of emitters
X
Kd
Built-in line
0.384
1.59 0.98
Built-on line
0.433
1.48 0.96
As a low value of the pressure exponent means that the discharge
is
less affected by pressure, hence the built-in tube has a less discharge
variation with respect to the pressure, however both emitters are
considered partially pressure compensating emitters.
4.3 Manufacturing variation (CV):
Table 4.3 shows the manufacturing variation (CV) values for the
two
types of emitters and the respective classification according to
equation
2.7 and Table 2.3 (App. 3)
Table 4.3 Manufacturing variation (CV)
Type of dripper
CV
Classification
Built in line
0.011
Excellent
Built on line
0.010
Excellent
4.4 The relation between the laterals lines length and emitters
discharge:
Tables 4.4, 4.5 and 4.6 show emitter discharge in (l/h) at 10 m
intervals
for the different types of drippers for 40, 60, and 80 m lateral
length.
Table 4.4 The relation between the laterals lines length and emitters
discharge at 40 m length.
Type of Pressure at
Distance (m)
average
dripper beginning
of lateral
0
10
(bar)
20
30
40
Discharge (l/h)
Built-in
0.5
3.05 2.96
2.98
2.92
2.84
2.95
line
1.0
4.01 3.90
3.92
3.79
3.64
3.85
Built-on
0.5
2.97 2.90
2.94
2.79
283
2.97
line
1.0
4.16 4.13
3.98
3.99
3.78
4.01
Table 4.5 The relation between the laterals lines length and emitters
discharge at 60 m length.
Type of Pressure at
average
Distance (m)
dripper beginning
of lateral
0
(bar)
10
20
30
40
50
60
Discharge (l/h)
Built-in
0.5
2.94 2.93 2.88 2.84 2.77 2.67 2.59
2.81
line
1.0
3.79 3.78 3.74 3.62 3.64 3.51 3.31
3.62
Built-on
.05
2.97 2.95 2.90 2.82 2.73 2.67 2.52
2.79
line
1.0
4.00 4.00 3.94 3.85 3.65 3.59 3.39
3.77
Table 4.6 The relation between the laterals lines length and emitters
discharge at 80 m length.
Type of
Pressure
dripper
at
Distance (m)
average
beginning 0
10 20 30
of lateral
40
50
60
70
80
Discharge (l/h)
(bar)
Built in
0.5
2.95 2.90 2.84 2.72 2.61 2.45 2.45 2.35 2.29
2.62
line
1.0
3.79 3.75 3.69 3.54 3.36 3.22 3.14 3.00 2.95
3.38
Built on
0.5
2.97 2.92 2.84 2.70 2.59 2.43 2.39 2.29 2.21
2.59
line
1.0
4.01 3.89 3.84 3.68 3.48 3.20 3.06 3.00 2.87
3.40
It is apparent that the average discharge decreases with the increase in
lateral length.
4.5 Emission uniformity (EU %)
Table 4.7 shows the emission uniformity (EU %) for different types of
emitters, lengths of laterals, pressures, and emitter cost, per Sudanese
Dinar for 100 meter, 50 cm spacing.
Table (4.7) Emission uniformity (EU %) for different types of
emitters and emitter cost.
Lateral length (m) Pressure (bar)
Emission uniformity
(EU%)
40
60
80
Cost SD / 100 m
Built-in
Built-on
0.5
96.3
95.3
1.0
94.5
94.2
0.5
92.1
90.3
1.0
91.4
89.9
0.5
88.4
85.3
1.0
88
84.4
___
11250
17500
App. 4 and Table 4.7 show that the emission uniformity (EU %) decreases
with the increasing lateral length, the following information can also be
drawn:
• The emission uniformity (EU %) of built-in and built-on lines at
working pressure of 0.5 bar, for 40 m length were found to be 96.3
% and 95.3 %
respectively, and they were the highest emission uniformities
compared with other lengths in the experiment.
• The emission uniformity (EU %) of built-in and built-on lines at
working pressure of 1.0 bar, for 40 m length were found to be 94.5
% and 94.2 %
respectively.
• The emission uniformity (EU %) of built-in and built-on lines at
working pressure of 0.5 bar, for 60 m length were found to be 92.1
% and 90.3 %
respectively.
• The emission uniformity (EU %) of built-in and built-on lines at
working pressure of 1.0 bar, for 60 m length were found to be 91.4
% and 89.9 %
respectively.
•
The emission uniformity (EU %) of built-in and built-on lines at
working pressure of 0.5 bar, for 80 m length were found to be 88.4
% and 85.3 % respectively.
• The emission uniformity (EU %) of built-in and built-on lines at
working pressure of 1.0 bar, for 80 m length were found to be 88 %
and 84.4 %
respectively.
• The cost of drip irrigation lines using built-on (Turbo-Key), 50 cm
spacing was approximately twice that for the built-in.
4.6 Reynold's number (Rn) and Blasius factor (f):
Reynold's number (Rn) was found to be 8450, 8775 for built-in and
built-on respectively App. 5 indicating turbulent flow regime since
RN > 4500 the flow regime is fully turbulent. According to the
Blasius
equation (2.4) the friction factor (f) for both built-in and built-on
was
found to be 0.033
4.7 The pressure variation (head loss) along the lateral length:
Table 4.8 Pressure variation along 40 m. lateral length.
Type of emitters
Distance (m)
0
10
20
30
40
Pressure (bar)
Built-in line
Built-on line
0.5
0.49 0.48 0.47
0.46
1.0
0.98 0.97 0.94
0.93
0.5
0.48 0.46 0.45
0.45
1.0
0.99 0.98 0.96
0.93
Table 4.9 Pressure variation along 60 m. lateral length.
Distance (m)
Type of emitters
0
10
20
30
40
50 60
Pressure (bar)
Built-in line
0.5 0.49 o.49 0.47 0.45 0.44
0.4
1.0 0.99 0.97 0.94 0.91 0.89 0.75
Built-on line
0.5 0.49 0.47 0.47 0.46 0.44 0.36
1.0 .098 0.97 0.96 0.94 0.88 0.81
Table 4.10 Pressure variation along 80 m. lateral length.
Distance (m)
Type of emitters
0
10
20
30
40
50
60
70
80
Pressure (bar)
Built-in line
0.5 0.48 0.45 0.40 0.36 0.31 0.30 0.27 0.25
1.0 0.97 0.92 0.83 0.72 0.64 0.58 0.53 0.49
Built-on line
0.5 0.48 0.44 0.38 0.32 0.30 0.29 0.24 0.23
1.0 0.96 0.91 0.80 0.72 0.63 0.55 0.51 0.46
Pressure variation due to lateral length at 5 m
pressure head
3
2
Built-in
1.5
Built-on
1
Head loss (m)
2.5
0.5
0
80
60
50
40
Lateral length (m)
Fig 4.1
6
5
4
Built-in
3
Built-on
2
1
Head loss (m)
Pressure variation due to lateral length at 10 m
pressure head
0
80
60
50
Lateral length (m )
40
Fig. 4.2
Figs 4.1 and 4.2 Summary of results for the pressure variation
(head loss) in meters for the different laterals types and lengths.
4.8 The calculated allowable pressure difference (head loss):
Table 4.11 shows the calculated allowable pressure difference ( head loss)
in meters for the different laterals types and lengths according to ASAE
technique, using equation (2.10), App. 6
Table 4.11 Calculated allowable pressure difference for the different
laterals types and lengths according to ASAE technique.
Type of emitters
Lateral beginning
Built-in line
Built-on line
Lateral length m
Pressure at the
40
50
60
80
(m)
Head losses (m)
5.0
0.48 o.64 1.01 1.64
10.0
1.42 1.41 1.87
5.0
0.54 0.57 1.12 1.69
10.0
0.92
1.1
2.8
1.65 3.67
The pressure decreases with increasing lateral length. The difference in the
pressure is allowable up to 50 meters lateral length.
4.9 Calculated pressure difference (head loss) according to DarcyWeisbach
equation:
Table 4.12 shows the calculated pressure difference, ( head loss) in meters for
the different laterals types and lengths according to Darcy-Weisbach
equation, using equation (2.11) and App.7
Table 4.12 Calculated allowable pressure difference for the different
laterals types and lengths according Darcy-Weisbach equation
Type of emitters Pressure at the
lateral beginning
Lateral length m
40
(m)
Built-in line
Built-on line
50
60
80
Head losses (m)
5.0
0.43 o.76 1.27 2.75
10.0
0.73 1.28 2.11
5.0
0.43 0.76 1.29 2.59
10.0
0.78 1.40 2.32 4.46
4.4
4.10 Calculated pressure difference (head loss) according to HazenWilliams
equation:
Table 4.13 shows the calculated pressure difference, ( head loss) in meters for
the different laterals types and lengths according to Hazen-Williams equation,
using equation (2.14), App. 8
Table 4.13 Calculated pressure difference for the different laterals types
and lengths according to Hazen-Williams equation.
Lateral length m
Type of emitters Pressure at the
Lateral beginning
(m)
Built-in line
Built-on line
40
50
60
80
Head losses (m)
5.0
0.44 o.93 1.28 2.54
10.0
0.72
5.0
0.45 0.93 1.26 2.49
10.0
0.78 1.67 2.05 4.11
1.5
2.21 4.07
Built-in
Pressure varriation
Built-on
3
2
1.5
1
Headloss (m)
2.5
0.5
0
d
re
su
ea d
M ure
40 as d
e
M ure
50 as d
e
M ure
60 as
e
M
80 AE
AS
40 AE
AS
50 AE
ch
AS
ba
60 AE eis ch
AS -W ba
80 rcy eis h
c
a
D -W ba
40 rcy eis ch
a
D -W ba
50 rcy eis s
a
D -W iam
60 rcy ill s
a W
D n- iam
80 ze ill s
a W
H n- iam
40 ze ill s
a W
H n- iam
50 e ill
az W
H ne
az
H
60
80
Fig 4.3 Comparison of head losses between allowable pressure difference
according to ASAE technique, Darcy-Weisbach equation, Hazen-Williams
equation, and actual measured pressure, under 5m working pressure.
Built-in
Built-on
Pressure variation
6
4
3
2
Head loss (m )
5
1
0
Da
Ha
Ha
Ha
Ha
ze
ze
ze
ze
n-
n-
W
W
W
n-
n-
am
i ll i
am
i ll i
am
i ll i
s
s
d
re
su
ea
M r ed
40 a su
e
M r ed
50 a su
e
M r ed
60 a su
e
M
80 AE
AS
40 AE
AS
50 AE
AS
ch
60 AE isb a
AS - We ach
y
80
b
c
s
r
ei h
Da
c
W
40 rcy - sb a
i
D a We ch
50 cy - sb a
r
i
D a We s
y - iam
rc
i ll
W
s
60
80
40
50
60
80
Fig 4.4 Comparison of head losses between allowable pressure difference
according to ASAE technique, Darcy-Weisbach equation, Hazen-Williams
equation and the actual measured pressure, under 10 m working pressure head
4.11 Squash water requirement:
Table 4.14 Estimating squash crop water requirement.
Month
Eto
Kc
Etc
Etc
Day
mm /day
mm /day
mm /month
February 18
6.034
0.5
3.17
57.06
March 31
6.913
0.95
6.57
203.59
April 26
7.41
0.75
5.56
150.05
Mean
6.79
0.73
5.1
136.87
October 26
5.832
0.5
2.92
75.92
November30
6.509
0.95
6.18
185.40
December 17
5.928
0.75
4.45
62.30
Mean
6.09
0.73
4.52
107.9
The mean monthly reference crop evapotranspiration for three
months
was found to be 6.8 mm/day in the first experiment (Feb. to April)
and 6.09 mm/day in the second experiment (Oct. to Dec.)
The calculated squash water requirement (Etsquash) for three
months
which represented the length of the growing season was found to be
5.1
mm/day for the first (Feb. to April) and 4.5 mm/day for the second.
(Oct. to Dec.) and as a result of this, squash water requirement
(Etsquash)
was found to be 4.8 mm/day. App. 9 to 11d.
4.12 Irrigation efficiencies for the first season (Feb-April):
Table 4.15 shows the average measured discharge in (l/h) and
emission uniformity (EU %) for the different types and positions of
laterals.
Table (4.16) Average measured discharge and emission uniformity (EU %)
for
the different types and positions of laterals, for the first season.
Types and positions
Average EU
Distance m
of lateral
(l /h)
%
3.95 3.81 3.88 3.78 3.66
3.81
96.1
Built-in-line 10 cm below 390 3.87 3.80 3.72 3.60
3.78
95.5
4.00
95.0
3.01
69.1
0
10
20
30
40
Discharge l/h
Built in-line above
soil surface
the soil surface
Built-on-line above soil 4.22 4.04 4.01 3.95 3.80
surface
Built-on-line 10 cm below 3.24 4.26 2.31 3.17 2.08
the soil surface
Plate 4.1 General view of the experimental field
4.12.1 Emission uniformity for squash lines (EU %):
With reference to Table 4.15 and App. 12 the emission uniformity
(EU%) was found to be 96.1% and 95.5% for built-in lines below and
above the soil surface respectively. For the built-on above soil,
surface it
was 95.0% where as for the built-on below the soil surface it was
found to
be 69.1% and this is attributed to the wide fluctuation in discharge
and
(EU%) due mainly to emitters clogging.
4.12.2 Water application efficiency:
Irrigation efficiencies (Ea) were found to be 93.3% and 92.5%
for
built-in lines below and above the soil surface respectively, and for
built-on above the soil surface they were found to be 92.9%. But for
the
built-on below the soil surface they were found to be 69.1%, this is
also
attributed to emitter clogging. The furrow efficiency was 40%-60%
which
is in line with Khalil findings, (1998).
Plate 4.2 Built-in and built-on (sub surface)
4.13 Irrigation efficiencies for the second season (Oct. - Dec.):
Table 4.16 shows the average measured discharge in (l/h) and
emission uniformity (EU %) for the different types and positions of
laterals
in the second season.
Table 4.17 Average measured discharge and emission uniformity (EU %)
for
the different types and positions of laterals for the second season.
Average EU
Distance (m)
Types and positions
(l /h)
%
3.95 3.94 3.89 3.83 3.71
3.86
96.1
3.90 3.83 3.84 3.77 3.61
3.79
95.3
4.05 4.07 4.03 3.96 3.80
3.98
95.5
2.44 2.08 3.78 2.56 3.17
3.41
61.1
of lateral
0
10
20
30
40
Discharge l/h
Built in-line above soil
surface
Built in-line 10 cm below
the soil surface
Built on-line above soil
surface
Built on-lines 10 cm
below the soil surface
4.13.1 Emission uniformity for squash lines (EU %):
With reference to Table 4.16 the emission uniformity (EU%) was
found to be 96.1.% and 95.3% for built-in lines below and above the
soil
surface respectively, and for the built-on above soil surface it was
95.5%,
for the built-on below the soil surface it was found to be 61.1% This
wide
fluctuation on discharge and (EU%) is attributed to emitters clogging
irrespective of the filtration which was incorporated with the built-on
emitters.
Plate 4.3 built-on above soil surface
Plate 4.4 Built-in above soil surface, with pressure gauge connected
4.13.2 Water application efficiency:
Irrigation efficiency (Ea) was found to be 93.5% and 92.8% for
the
built-in lines below and above the soil surface respectively. For the
built-on
above the soil surface it was found to be 92.9%., where as for the builton
below the soil surface it was found to be 59.5%, still emitters clogging
is
considered the main reason for that.
Table 4.18 Squash plant parameters (first season)
Parameters
Irrigation
system
Built-in
Yield
Leaf width
Plant height
Plant diameter
Kg/line
cm
cm
cm
Max Min Mean Max Min Mean Max Min Mean
25
23
24
57
52
55
53
51
52
45.4
25
22
23
56
50
54
52
53
53
46.7
22
9
18
54
8
31
50
18
34
23.7
25
23
24
51
48
50
51
48
50
45.6
27
10
19
58
11
35
52
17
35
29.3
subsurface
Built-in
surface
Built-on
subsurface
Built-on
surface
Furrow
4.14 Water use efficiency WUE (first season)
Efficiency of water use was found to be 2.3, 2.67, 1.20, 2.3, 1.49
Kg/m3 for built-in
subsurface
built-in
surface,
, built-on
subsurface,
built-on
surface,
and
furrow lines respectively App 13. The results show the
superiority of
drip irrigation over the furrow method, guard statistic.
Table 4.19 Squash plant parameters (second season)
Parameters
Irrigation
system
Built-in
Leaf width
Plant height
Plant diameter
cm
cm
cm
Max Min Mean Max Min Mean Max Min Mean
Yield
Kg/line
25
23
24w
57
52
55h
53
51
52
44.7
23
22
23
56
50
54
52
53
53
45.3
23
8
15
54
9
33
51
15
33
32.2
23
21
22
51
48
50
51
50
50
45
25
11
18
58
11
35
52
16
34
37.1
subsurface
Built-in
surface
Built-on
subsurface
Built-on
surface
Furrow
4.15 Water use efficiency WUE (second season)
Water use efficiency was found to be 2.27 ,2.3, 1.6, 2.8, 1.9
Kg/m3
for built-on subsurface built-in surface, , built-on subsurface, built-on surface, and
furrow lines respectively. The results show the superiority of drip
irrigation over the furrow method, guard statistic.
4.16 Soil properties:
The soil of the experimental site was heavy clay with clay content
of
65% at the top 15 cm layer. The soil was moderately alkaline (pH 7-8).
This is in line with the findings of Saeed (1968). The infiltration rate
according to Ferguson (1970) was 20 mm / hr in the first two hours
and
5 mm / h after 10 hours. The field capacity on dry weight basis was
27.%
while the permanent wilting point was 13% , this would result in an
average available soil moisture content of 14% App. 14. The mean
bulk
density was 1.3 g / cm3 for the dry soil according to Khalil (1998) and
Bashir, (2001) who worked in the same site.
4.18 Squash plant under drip irrigation
The squash crop (Plate 4.1) was taken as an indicator crop.
Plate 4.6 Squash plant
Reduction factor (Kr);
Plant dimensions were measured to compute the reduction
factor
(Kr).From Tables 4.18, 4.19 and App. 15 the average ground cover
was found to be 0.77 and hence the reduction factor was 91%. Net
irrigation requirement (In) was found to be 4.6 and 4.1 mm / day for
the
first and second seasons respectively.
Gross irrigation requirement (Ig) was found to be 5.1 and 4.6 mm /
day
for the first and second seasons respectively.
The depth of water applied as determined by equation (2.35) was
11.47
mm /day.
Irrigation interval was found to be 3 days.
Irrigation set time (T) was found to be 0.9 hour using equation (2.36)
The amount of fertilizer was found to be 29 liter solution fertilizer.
The rate of fertilizer injection (Qf) was found to be 8 liters per hour for
built-in and built-on using equation (2.1), per one set irrigation, in the
accordant of not more than one kilogram fertilizer per cubic meter of
water.
4.19 Squash plant under Furrow line:
The discharge (Q) was found to be 740.8 (l/h) for the furrow
line.
Net irrigation requirement (NIR) was found to be 21 mm /day.
Gross irrigation requirement (GIR) was found to be 35 mm /day.
Irrigation intervals (Ii) was found to be 7 days.
Irrigation set time (T) was found to be 2.5 hour. (App. 16)
Plate 4.7 furrow line (control)
Plate 4.8 Furrow line showing high weed infestatio
4.20 Data Analysis:
Table 4.20 Analysis of variance
Source
(df) M.S
F
Calculated Scheduled
4.056
2.67
built-on surface ,built-in 4
surface built-in , subsurface 25
X Furrow
39.323
9.695
built-on
X
surface
Furrow
built-on surface ,built-in
surface built-in , subsurface
Yield
1
9
4
25
4
4.356
0.819
5.32
39.323
4.056
9.695
7786.219 7581.518
2.87
3
1527.302 1487.149
3.10
12
7395.792 7201.355
2.28
3
275.111
3.49
2
1779.292 717.168
3.89
6
29.403
116.17
3.00
4
217.638
3.487
3.06
2
1.059
0.017
8
6.105
0.1
3
369.084
0.804
3.1
3
2363.993 5.156
3.1
9
5136.484 11.203
2.39
Plant diameter
leaf width
Plant height
1100.444
2.67
2.67
Table 4.20 gives a summary for App. 17 that shows that there are
significant differences (p ≤ 0.05) between the built-in lines below and
above the soil surface, and built-on above the soil surface as compared
with furrow system, with respect to crop yield, plant height and plant
diameter, but for leaf width is significant difference was found (p ≤
0.05).
CAPTER FIVE
CONCLUSIONS AND RECOMMENDATIONS
5.1 Conclusions:
From the results of this study the following conclusions can be
drawn:
• Darcy-Weisbach and Hazen-Williams equations have similar
results for lateral hydraulic calculations.
• For high performance of drip irrigation the lateral length
should not be more than 50 meters, particularly when
partially pressure compensating emitters are used.
• Built-on emitters should not to be used below soil surface.
• Using Penman-Monteith formula, the estimated squash
water requirement (ETsquash) was found to be 4.8 mm/day
under Shambat conditions.
• Drip irrigation systems produce more yield per unit area
and yield per unit volume of water than conventional
surface
irrigation system.
5.2 Recommendations:
• For a perfect drip irrigation system design it is necessary to
consider the manufacturing coefficient of variation under the
recommended pressure.
• For a higher performance of drip irrigation system the
matching type of filter and the recommended number of mesh
must be used.
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APPENDICES
Appendix (1) discharge distribution:
Distance built-on (0.5 bar)
Average
0
3.25 3.32 3.16 3.15 3.23 2.95 3.20 2.86 2.98 3.16 3.13
10
3.19 3.1
20
2.83 2.96 2.87 2.79 2.8
30
3.03 3.84 2.95 2.88 2.67 2.60 2.28 2.79 2.77 2.81 2.86
40
2.71 3.00 2.86 2.73 2.68 2.87 2.63 3.15 2.89 2.82 2.83
3.16 3.18 3.13 3.00 2.95 3.2
3.03 3.25 3.07
2.56 2.77 2.90 3.09 2.85 2.94
Average
2.97
Distance built-in (0.5 bar)
Average
0
3.15 3.15 3.16 3.05 3.10 2.89 3.03 2.98 2.99 3.04 3.05
10
3.21 3.38 2.99 2.84 2.87 2.85 2.94 2.97 2.87 2.7
29.6
20
3.18 2.94 3.06 3.06 2.99 2.96 2.97 2.90 3.15 2.95 2.98
30
3.13 3.24 2.95 2.88 2.67 2.90 2.88 2.89 2.87 2.81 2.92
40
2.71 3.01 2.86 2.73 2.68 2.87 2.63 3.15 2.89 2.82 2.8 4
Average
2.95
Distance built-in (1.0 bar)
Average
0
4.06 4.15 3.99 4.00 3.96 4.18 4.02 3.89 4.17 4.12 4.01
10
4.01 4.14 4.00 3.86 4.01 3.95 4.07 3.96 3.69 4.11 3.98
20
3.97 3.90 3.85 3.86 3.67 3.74 3.64 3.97 3.86 3.68 3.80
30
4.00 3.86 4.00 3.73 3.78 3.65 3.58 3.80 3.69 3.55 3.76
40
3.89 3.76 3.84 3.67 3.70 3.61 3.54 3.75 3.52 3.62 3.69
3.85
Average
Distance
built-on (0.5 bar)=
Average
Distance built-on (1.0 bar)
Average
0
4.26 4.35 4.09 4.20 3.96 4.28 4.12 4.09 4.17 4.12 4.16
10
4.31 4.25 4.00 4.22 4.11 3.95 4.17 4.08 3.99 4.21 4.13
20
4.01 4.14 4.00 3.86 4.01 3.95 4.07 3.96 3.69 4.11 3.98
30
4.10 4.27 3.97 4.06 3.87 3.89 4.02 4.07 3.82 3.85 3.99
40
3.96 4.08 4.00 3.73 3.79 3.69 3.69 3.68 3.69 3.51 3.78
Average
4.01
Distance built-in (1.0 bar)
Average
0
4.07 4.04 3.98 3.81 3.85 3.79 3.79 3.58 3.50 3.49 3.79
10
4.00 3.96 3.90 3.63 3.71 3.75 3.63 3.78 3.65 3.59 3.76
20
3.72 3.66 4.02 4.15 3.63 3.77 3.56 3.65 3.64 3.69 3.74
30
3.98 3.77 3.82 3.77 3.60 3.64 3.56 3.65 3.52 3.57 3.69
40
3.79 3.76 3.90 3.88 3.52 3.67 3.50 3.05 3.68 3.65 3.64
50
3.80 3.79 3.7
60
3.71 3.56 3.42 2.95 3.33 3.32 3.05 3.23 3.30 3.26 3.31
3.55 3.67 3.46 3.57 3.37 3.46 2.62 3.51
Average
3.62
Distance built-on (1.0 bar)
Average
10
4.22 4.11 3.97 3.94 3.80 4.01 4.02 4.08 3.91 3.94 4.00
10
3.79 4.02 4.05 3.97 4.18 4.02 3.98 4.08 3.86 4.05 4.00
20
4.14 4.08 3.85 3.89 3.85 3.90 4.13 3.71 3.97 3.88 3.94
30
4.02 4.07 3.96 3.81 3.75 3.65 3.73 3.68 3.79 4.07 3.85
40
3.66 3.99 3.78 4.00 3.63 3.42 3.78 3.58 3.57 3.11 3.65
50
3.51 3.48 3.61 3.53 3.65 3.51 3.62 3.52 3.61 3.86 3.59
60
3.61 3.77 3.49 3.38 3.66 3.83 2.82 2.96 2.81 3.06 3.39
Average
3.77
Distance built-on (0.5 bar)
Average
10
3.36 3.24 2.99 2.97 2.85 2.92 2.91 3.00 2.67 2.81 2.97
10
3.08 2.94 3.10 3.11 2.79 2.99 2.88 2.70 2.86 3.05 2.95
20
3.03 3.07 2.88 2.74 2.75 2.83 3.02 2.98 2.76 2.94 2.90
30
2.90 2.98 2.98 2.71 2.73 3.07 2.77 2.78 2.75 2.55 2.82
40
2.77 2.93 2.72 2.65 2.94 2.74 2.82 2.54 2.59 2.64 2.73
50
2.90 2.91 2.95 2.78 2.76 2.77 2.66 2.72 2.64 2.50 2.76
60
2.61 2.72 2.57 2.35 2.67 2.46 2.67 2.54 2.56 2.32 2.52
Average
2.79
Distance built-in (0.5 bar)
Average
10
2.93 2.97 3.00 2.92 2.92 2.96 3.03 2.93 2.84 2.90 2.94
10
2.95 2.89 3.20 2.72 3.00 2.89 2.98 2.78 2.89 3.00 2.93
20
2.91 3.09 2.76 2.90 2.73 2.94 2.78 2.66 2.67 3.39 2.88
30
2.80 2.83 2.98 2.66 2.93 3.20 2.78 2.75 2.64 2.64 2.84
40
2.50 2.85 2.76 2.80 2.74 2.87 2.94 2.70 2.65 2.89 2.77
50
2.62 2.66 2.59 2.75 2.56 2.57 2.72 2.66 2.69 2.90 2.67
60
2.48 2.49 2.62 2.63 2.85 2.53 2.62 2.52 2.63 2.52 2.59
Average
2.81
Distance built-on (0.5 bar)
Average
10
3.06 3.04 2.89 2.97 3.04 2.92 2.92 3.10 2.88 2.90 2.97
10
2.95 3.07 2.95 2.84 2.79 2.93 3.05 2.98 2.72 2.74 2.92
20
2.60 2.80 2.87 2.65 2.83 3.20 2.88 2.75 2.75 2.63 2.84
30
2.72 2.56 2.69 2.74 2.59 2.53 2.62 2.67 2.69 2.79 2.70
40
2.39 2.58 2.40 2.75 2.77 2.71 2.53 2.61 2.67 2.50 2.59
50
2.62 2.83 2.77 2.71 2.78 2.76 2.62 2.74 2.40 2.93 2.43
60
2.42 2.21 2.24 2.29 2.75 2.13 2.37 2.25 2.31 2.53 2.35
70
2.43 2.42 2.26 2.23 2.27 2.15 2.13 2.56 2.29 2.16 2.29
80
2.07 2.29 2.55 2.03 2.05 2.17 2.13 2.16 2.32 2.30 2.21
Average
2.59
Distance built-on (1.0 bar)
Average
0
4.04 4.18 401
3.91 3.87 4.01 4.05 3.95 3.91 4.09 4.01
10
3.97 4.11 3.96 370
20
3.81 3.90 3.87 3.85 3.73 399
30
3.59 3.75 3.57 3.80 3.84 3.59 3.65 3.63 3.67 3.64 3.68
40
3.71 3.68 3.51 3.53 3.65 3.31 3.52 3.52 3.60 3.56 3.48
50
3.24 3.17 3.33 3.39 3.15 3.22 3.05 3.24 3.24 3.01 3.20
60
2.93 2.80 2.87 2.76 2.97 2.88 2.91 2.71 2.83 2.90 3.06
70
3.25 2.95 2.78 2.87 2.93 2.82 3.08 2.73 2.86 3.14 3.00
80
2.91 2.87 2.94 2.90 3.19 3.08 2.82 3.01 2.92 2.89 2.87
3.86 3.94 3.87 3.73 3.68 3.92 3.89
3.78 3.75 3.84 3.83 3.84
Average
3.4
Distance built-in (0.5 bar)
Average
10
2.82 2.74 2.81 3.05 2.93 2.92 2.87 2.86 2.96 3.00 2.95
10
2.56 2.62 2.76 2.57 2.77 2.95 2.88 2.68 2.64 2.71 2.90
20
2.92 2.86 2.72 2.69 2.87 2.68 3.20 2.79 2.78 2.81 2.84
30
2.70 2.89 2.76 2.79 2.80 2.75 2.65 2.98 2.08 2.85 2.72
40
2.51 2.69 2.84 2.65 2.67 2.59 2.50 2.51 2.52 2.54 2.61
50
2.63 2.43 2.35 2.26 2.47 2.23 2.86 2.39 2.36 2.42 2.45
60
2.43 2.36 2.36 2.59 2.35 2.13 2.37 2.35 2.43 2.23 2.45
70
2.22 2.11 2.24 2.29 2.75 2.43 2.37 2.25 2.31 2.53 2.35
80
2.07 2.29 2.55 2.08 2.05 2.17 2.13 2.19 2.32 2.33 2.29
Average
2.62
Distance built-in (1.0 bar)
Average
0
4.06 4.05 3.76 383
10
3.95 4.3
3.4
20
3.81 358
3.69 3.51 3.86 3.56 3.55 3.65 3.68 3.69 3.69
30
3.49 3.71 3.40 3.45 3.76 3.31 3.60 3.54 3.58 3.55 3.54
40
3.10 3.32 3.39 3.25 3.45 3.57 3.15 3.33 3.40 3.54 3.36
50
3.33 3.36 3.11 3.25 3.09 3.15 3.27 3.14 3.33 3.14 3.22
60
313
70
3.20 301
80
3.02 2.64 2.71 3.05 2.63 2.92 3.07 2.81 2.96 3.20 2.95
Average
3.94 3.62 3.89 3.87 3.43 4.26 3.79
3.90 3.86 3.51 3.64 3.68 3.68 3.94 3.75
3.31 3.22 3.13 3.24 2.97 3.02 3.16 2.95 3.04 3.14
304
2.89 2.79 2.84 3.08 2.76 2.81 3.05 3.00
3.38
Appendix (2)
Discharge exponent (X) and (Kd) coefficient:
Q = K d Hx
Built-in:
Q1 = 2.95, Q2 = 3.85
X=
H1 = 5m, H2 = 10m
log (Q1/Q2)
log (H1/H2)
= log (2.95/3.85) = 0.384
log (5/10)
Kd = 3.85/ 100.384 = 1.59
Built-on:
Q1 = 2.97 l/h, Q2= 4.01 l/h
X=
H1= 5m, H2= 10m
log (2.97/4.01) = 0.433
log (5/10)
Kd = 4.01/100.433 = 14.8
Q = Kd.HX
discharge (Q)
Built-in 40 = 3.85
60 = 3.62
80 = 3.38
discharge (Q)
Built-on 40 = 4.01
1.48
60 =3.77
1.39
80 = 3.4
X=
.384
HX = 2.42
(3.85 = 2.42K)
(3.62 = 2.42K)
(3.38 = 2.42K)
X
= .433
HX = 2.71
(4.01 = 2.71K)
Kd =
(3.77 = 2.71K)
Kd =
( 3.4 = 2.71K)
Kd =
1.25
r2 =
Kd =1.59
Kd =1.5
Kd = 1.4
(n Σ xy - Σ x y)2
[n Σx2 - (Σ x2)] [n Σ y2 -
Σ y2 ]
r2 = 0.98 and 0.96 for built-in and built-on respectively
Appendix (3)
Coefficient of Manufacturing Variation (CV):
____________________________________________
Built-in line (cv) = √ (4.01)2+ (3.9)2+ (3.92)2+ (3.64)2+ (3.79)2 – 5/ (3.85)2/4
3.85
=
0.011
___________________________________________
Built-on line (cv) =√ (4.26)2+ (4.12)2+ (3.92)2+ (3.94)2+ (3.80)2–
5(4.01)2/4
4.01
=
0.010
Appendix (4)
Uniformity of system hydraulic studies (EU%):
EU = (Qmin /Qave) 100%
Built-in 0.5 bar length 40m (2.84 / 2.95) 100 = 97.4%
Built-in 0.5 bar length 60m (2.59 / 2.81) 100 = 92.2%
Built-in 0.5 bar length 80m (2.29 / 2.62) 100 = 87.4%
Built-in 1.0 bar length 40m (3.72 / 3.85) 100 = 96.6%
Built-in 1.0 bar length 60m (3.48 / 3.62) 100 = 92.8%
Built-in 1.0 bar length 80m (2.97 / 3.38) 100 = 87.9%
Built on 0.5 bar length 40m (2.83 / 2.97) 100 = 95.3%
Built-on 0.5 bar length 60m (2.52 /2.79) 100 = 90.3%
Built-on 0.5 bar length 80m (2.21 /2.59) 100 = 85.3%
Built-on 1.0 bar length 40m (3.85 /4.01) 100 = 96.0%
Built-on 1.0 bar length 60m (3.40 /3.77) 100 = 90.2%
Built-on 1.0 bar length 80m (2.87 /3.40) 100 = 84.4
Appendix (5)
Reynolds number(RN),Blasius friction factor (f) and Christensens
friction (F)
a- (for built-in tube, pressure 1.0 bar, length 40 m)
RN = VD / (1000v)
V = Q /A (l/h)
=
308/(1000×3600)
(0.0065)2 ×3.142
V = 0.64 m/sec
RN = 0.65 ×13 × 1000 = 8450
b- (for built-on tube, pressure 1.0 bar, length 40 m)
V=
V=
320.8/(1000×3600)
(0.0065)2 ×3.142
0.675 m/sec
RN = 0.675 ×13 × 1000 = 8775
Where (RN > 4500) so the regime of the flow is fully turbulent
and,
according to the Blasius equation the friction factor (f) for
turbulent
flow is, f = o.316/RN0.25
f = 0.316 /8450.25 and 0.316 /8775.25 = 0.033 for builtin
and built-on respectively.
Christensen's friction factor (F) for 80 emitter:
1 + 1
+ ( m – 1)0.5
m +1
2(80)
6(80)2
Christensen's friction factor (F) with (m = 1.852) for 80, 100, 120,160
F=
outlet was found to be: 0.357, 0.356, 0.355, 0.353 respectively.
Christensen's friction factor (F) with (m = 2) for 80, 100, 120,160 outlet
was found to be: 0.340, 0.338, 0.337, 0.336 respectively.
Appendix (6)
6.1 Allowable Pressure difference ASAE Technique:
∆P = 1/X (dq) h
(Q)
6.1.1 Built-in 0.5 bar
X
= 0.384
∆P =
1/X = 2.6
40m length 2.6 (0.11) 5
(2.95)
= 0.484m
=
50m length 2.6 (0.17) 5 = 0.778m
(2.84)
=
60m length 2.6 (0.22) 5 = 1.017m
(2.81)
=
80m length 2.6 (0.33) 5 = 1.637m
(2.62)
6.1.2 Built-in 1.0 bar:
40m length 2.6 (0.21)10 = 1.418m
(3.85)
50m length 2.6 (0.20)10 = 1.41m
(3.68)
60m length 2.6 (3.62)10 = 1.867m
(3.62)
80m length 2.6 (0.41)10 = 3.153m
(3.38)
6.1.3 Built-on:
X
= 0.433
1/X = 2.31
∆P 0.5 bar, 40m length = 2.31 (0.14) 5 = 0.544m
(2.97)
50m length = 2.31 (0.17) 5 = 0.691m
(3.77)
60m length = 2.31 (0.27) 5 = 1.177m
(2.97)
80m length = 2.31 (0.38) 5 = 1.694m
(2.59)
6.1.4 Built-on: 1.0 bar,
40m length = 2.31 (0.16) 10 = 0.921m
(4.01)
50m length = 2.31 (0.17)10 = 1.382m
(2.84)
60m length = 2.31 (0.25) 10 = 2.267m
(3.77)
80m length = 2.31 (0.53) 10 = 4.82m
(3.40)
Appendix (7)
Head loss according to Darcy–Weisbach equation:
hf = 6.377 fL Q2 /D5
Where: L =lateral length (m); Q = [q (emitters average
discharge)×N (No. of outlets -l/sec )]; D (inner diameter) =
13mm
hf = 6.377×0.033×40×2362 /135
For the built-in with a begging pressure of 0.5 bar, the pressure head
loss was found to be 0.43, 0.764, 1.29, 2.75 meters for 40, 50, 60,
80
(m) lateral length respectively.
For the built-on with a begging pressure of 0.5 bar, the pressure head
loss was found to be 0.43, 0.76, 1.27, 2.59 meters for 40, 50, 60,
80
(m) lateral length respectively.
For the built-in with a begging pressure of 1.0 bar, the pressure head
loss was found to be 0.73, 1.28, 2.11, 4.4 meters for 40, 50, 60, 80
(m) lateral length respectively.
For the built-on with a begging pressure of 1.0 bar, the pressure head
loss was found to be 0.78, 1.4, 2.32, 4.46 meters for 40, 50, 60, 80
(m) lateral length respectively.
Appendix (8)
Head losses according to Hazen–Williams equation: (with C= 140)
hf = KL [Q/1401.852]
D4.87
K =1.21×1010 ;L = lateral length (m); Q = [q (emitters average
discharge)×N (No. of outlets- l/sec )] D (inner diameter) =
13mm
For the built-in with a begging pressure of 0.5 bar, the pressure head
loss was found to be 0.443, 0.933, 1.279, 2.538 meters for 40, 50,
60, 80
(m) lateral length respectively.
For the built-on with a begging pressure of 0.5 bar, the pressure head
loss was found to be 0.448, 0.933, 1.263, 2.485 meters for 40, 50,
60, 80
(m) lateral length respectively.
For the built-in with a begging pressure of 1.0 bar, the pressure head
loss was found to be 0.722, 1.505, 2.205, 4.068 meters for 40, 50,
60, 80
(m) lateral length respectively.
For the built-on with a begging pressure of 1.0 bar, the pressure head
loss was found to be 0.782, 1.671, 2.045, 4.113 meters for 40, 50,
60, 80
(m) lateral length respectively.
April
March
Feb.
36.5
40.4
36.5
T.
max
32.6
25.9
20.4
24.1
20.3
T.
min
16.8
28.1
32.6
28.5
32.2
28.4
Tc◦
mean
24.7
0.184
0.153
0.199
0.226
0.269
0.226
0.184
39.3
29
41
48
17.3
15
16
21
2
2
2
2
2
2
2
2
11.3
11.1
11.2
11.6
11.9
12.4
11.9
11.5
-0.399
- 0.58
- 0.63
0.014
0.357
0.532
0.518
0.21
G
3.915
3.075
3.780
4.891
3.691
4.739
3.089
3.075
es
1.578
1.135
1.250
2.348
0.661
0.713
0.623
0.646
ea
Ra
Mean
39.3
21.0
24.4
0.179
Month Tempura
Oct.
35.2
17.0
28.4
Mj/m²/day
Nov.
31.7
21.3
Wind
speed
m/sec
Dec.
35.4
∆
Relative
Kpa/c◦ Humidity
%
Mean
ea = es × relative humidity as a friction ….......... (2.24)
Mean monthly meteorological data and the values of Penman Monteith formula elements.
Appendix (9)
Appendix (10)
Value of vapor pressure deficit for measurement at 2 m high. (es – ea)
Feb:
ea = 3.075× 0.21 = 0.646
March: ea = 3.089× 0.21 =0.494
April: ea = 4.739× 0.21 =0.719
Oct.:
ea = 4.891× 0.21 =1.445
Nov.: ea = 3.780× 0.21 =0.983
Dec.:
ea = 3.075× 0.21 =0.892
Appendix (11)
Value of soil heat flux (G) (Mj m-2 day-1).
G moth = 0.14 (T month – T month-1) ………………......... (2.23)
G Feb.
= 0.14 (24.7 – 23.2) = 0.21
G March = 0.14 (28.4 – 24.7) = 0.518
G April = 0.14 (32.2 – 28.4) = 0.532
G Oct.
= 0.14 (32.6 –32.5) = 0.014
G Nov. = 0.14 (28.1 –32.6) = -0.63
G Dec. = 0.14 (24.4 –28.1) = -0.58
Appendix (11a)
Penman-Monteith formulas:
Eto = 0.408 ∆ (Ra – Q1) + Y [(900)/ (T + 273)] × U2 (es – ea) ….(2.21)
∆ + Y (1 + 0.34 U2)
February:
Eto = 0.408 × 0.184 (11.5 – 0.21) + 0.066[(900)/(247+273)]2(3.075 –
0.696)
0.184 + 0.066 (1 + 0.34 × 2)
= 6.034mm/day
March:
Eto = 0.408 × 0.006 × 11.823 + 0.066 (2.986 × 2 × 3.262)
0.226 + 0.111
= 6.913 mm/day
April:
Eto = 0.408 × 0.269 × 11.308 + 0.66 (2.949 × 2 × 4.04)
0.269 + 0.111
= 7.41 mm/day
October:
Eto = 0.408 × 0.199 × 11.586 + 0.066 (2.95 × 2 × 9.505)
= 5.832 mm/day
November:
Eto = 0.408 × 0.153 × 11.83 + 0.066 (3.395 × 2 × 2.23)
0.153 + 0.111
= 6.569 mm/day
December:
Eto = 0.408 × 0.184 × 11.68 + 0.066 (3.026 × 2 × 2.183)
0.184 + 0.111
= 5.928 mm/day
Appendix (12)
Uniformity of the squash drip irrigation lines (EU%)
EU % = (Qmin /Qave) 100%
Built-in line above soil surface (3.66 3.81) = 96.1%
Built-in line 10 cm below the soil surface (3.60/ 3.78) = 95.5%
Built-on line above soil surface (3.80 /4.00) = 95.0%
Built-on lines 10 cm below the soil surface (2.08 / 3.01) = 69.1%
Appendix (13)
Irrigation efficiency (Ea):
Ea =Ks × EU………….. (2.34)
Ks% = {100(clay) + 97(loam) + 95(fine sand)} / 3 = 97.3% (Ismail,
2002)
Built-in line above soil surface
(97.3× 96.1) = 93.5 %
Built-in line 10 cm below the soil surface (97.3× 95.5) = 92.9 %
Built-on line above soil surface
(97.3× 95.0) = 92.4 %
Built-on line 10 cm below the soil surface (97.3× 69.1) = 67.2 %
Furrow line(Control)
= 60%
Appendix (14) Squash:
Reduction factor (kr) 77 / 85 = 91%.
Depth of water to be applied (D) under drip irrigation system
=10 (Fc - pwp) d × z × p (equation
2.35)
= 10 × 0.3 × (27– 13) ×0.3 × 0.91= 11.47 mm /day
Gross irrigation requirement (GIR) = NIR / E
11.47/93 = 12.33 mm /day
Irrigation intervals (Ii) =NIR / ETc
= 11.47 / 4.8 = 3 days.
Irrigation set time (T) = ETc ×Se ×SL ×K / Q × E (equation 2.36)
= 0.5×1.4×4.8× × / 4 = 0.9 hour.
Appendix (15)
Furrow line discharge:
Discharge
Discharge
litre / 5 minutes
Litre / hour
62.4
748.8
57.6
691.2
60.7
728.4
65.6
797.2
64.7
776.4
53.4
640.8
63.0
756
63.2
758.4
54.3
651.6
71.6
859.2
Average
74 0.8
The discharge (Q) was found to be 740.8 (l/h) for the furrow line.
Net irrigation requirement (NIR) = MAD (Fc - PWP)
= 0.5 × (27– 13) ×0.3 = 21 mm
/day
Gross irrigation requirement (GIR) = NIR /Ea (60%)
= 21 / 0.6 = 35 mm /day.
Irrigation intervals (Ii) = NIR / ETc
= 35 / 4.8 = 7 days.
Irrigation set time (T) = 0.5×1.4×4.8×80 ×7 / 740.8 = 2.5 hour.
Appendix (16)
Rep. No. Weight gm
wetted soil
1
48.6
2
52.4
3
51.9
4
44.9
5
47.2
6
57.3
7
53.2
8
43.4
9
48.1
10
55.2
Average 50.22
dry soil
37.7
41.4
39.5
35.8
37.7
44.8
40.6
35.3
38.0
43.8
39.46
Moisture
10.9
11
12.4
9.1
9.5
12.5
12.6
8.1
10.1
11.4
10.76
FC
PWP AW
Øm%
28.9
26.6
31.4
25.4
25.2
27.9
31
22.9
26.6
26
27.19
%
13
13
13
13
13
13
13
13
13
13
13
%
15.9
13.6
18
12.4
12.2
15.9
18
9.9
13.6
13
14.19
Appendix (17)
analysis of variance of (built-on subsurface X furrow)
Source
Sum of squares Degrees of Variance
freedom
(df)
Between SSB = 4.356
V1 = 1
S2B = 4.356
groups
With in
SSW= 47.888 V2 = 9
S2W = 5.32
groups
Total
SST = 52.244 N-1 =10
F
Calculate Schedule
d
d
0.819
2.67
analysis of variance (built-on surface X built-in surface X built-in
subsurface X built-on subsurface X furrow)
F
Source
Sum
of Degrees of Variance
squares
freedom (df)
Calculate Schedule
d
d
2
Between
SSB
= V1 = 2
SB
= 0.344
2.67
groups
02.133
1.067
With in
SSW=
V2 = 12
S2W = 3.1
groups
37.200
Total
SST
= N-1 =14
39.333
analysis of variance (built-on surface X
subsurface
Source
Sum
of Degrees of
squares
freedom
(df)
Between
SSB
= V1 = 4
groups
157.290
With in
SSW
= V2 = 25
groups
242.378
Total
SST
= N-1 =29
399.668
analysis of variance of leaf width
built-in surface X built-in X
Variance
S2 B
39.323
S2 W
9.695
F
Calculate Schedule
d
d
2.67
= 4.056
=
Source
Sum of squares
Degrees
of Average
freedom (df)
F
of
Calculat
Schedule
squares
ed
d
Replicate
SSR = 1107.253
4-1=3
369.084
0.804
3.1
Treatment
SSC = 7091.978
4-1=3
2363.993
5.156
3.1
Interaction
SSI = 46228.359
3×3=9
5136.484
11.203
2.39
Error
SSE = 7335.842
4× 4×(2-1) = 458.490
0.172
2.99
16
MSR
PMSE
Total
/ 369.084
/ 25
2142.568
4× 4×(2)- 1=
31
analysis of variance of plant yield
Variance
Sum of squares
Degrees
source
Rows
of Average
freedom (df)
SSR
= 5-1=4
F
of
Calculate
Schedule
squares
d
d
7786.219
7581.518
2.87
31144.874
Columns
SSC = 4581.907
4-1=3
1527.302
1487.149
3.10
Interaction
SSI = 88749.501
4 × 3 = 12
7395.792
7201.355
2.28
Error
SSE = 20.53
5× 4×(2-1) = 1.027
20
Total
5× 4×(2)- 1=
39
analysis of variance of plant diameter
Source
Source
Replicate
Treatment
Rows
Columns
Interaction
Interaction
Error
Error
Total
Sum of squares
Degrees
of Average
freedom (df)
of squares Calculate
Degrees
of Average F
d
freedom (df) of
Calculate
SSR = 825.334 4 - 1 = 3
275.111
1100.444
squares
d
SSC
= 3-1=2
1779.292 717.168
SSR = 5870.553 5 - 1 = 4
217.638
3.487
3558.583
SSC==176.416
2.117
3-21==62
1.059
0.017
SSI
3×
29.403
116.17
Sum of squares
SSI =
SSE
= 48.837
3
× 2= 8= 12
4×43(2-1)
6.105
0.25
SSE = 936..312 4×5×
4×(2-1)
= 62.421
3×(2)1= 23
15
Total
F
5× 4×(2)- 1=
29
analysis of variance of plant height
0.1
Schedule
d
Schedule
3.49
d
3.89
3.06
3.00