1. No category

Nitrogen advice in
Flanders
Joris De Nies
Research station for Vegetables
St-Pol-de-Léon,
Le 10 décembre 2014
Congrès « Chou-fleur : Les enjeux de la production européenne »
Problems with nitrogen
Strict legislation on nitrogen

General
– Ca 767 measuring points on surface water for water quality (max NO3
50 mg/L)
– Ca 2100 measuring points on groundwater for water quality

Specific for horticulture
– Measurements of nitrogen in soil (oct-nov)max 85-90 kgN-NO3/ha
– Horticulture 2013: Obligated “advisory system” for vegetables
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Principle KNS-system
Origine: Germany, Pfalz
Kultur-begleitenden Nmin-Sollwert system
Main principle
Based on target values for nitrogen and the N-content in the
soil, according to rooting depth
–
–
–
–
Soil samples at planting
Long growing period (after 5-8 weeks additional samples)
Avoiding unpredicted climate conditions (eg rain)
Incorporate mineralisation by measuring more frequently (soil
mineralisation, crop residues, green manure)
– Preventing leaching out
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KNS in cauliflower
weeks after plant
N-uptake
cumulative N-uptake
Latent N
Rooting depth
Target value N(0-30)
Target value N(0-60)
TV with min. (0-30)
TV with min. (0-60)
1
1
1
120
30
195
167
Cauliflower
2
3
4
4
8
20
5
12
33
120 120 120
30
30
30
194 190 182
166
162
5
42
75
120
30
6
64
139
80
30
7
57
196
80
60
8
32
228
80
60
9
12
240
80
60
287
245
181
124
92
252
210
146
89
57
154
Target value (TV) 1
N-application (kg N/ha) = TV 1 - N-application (kg N/ha) = TV 2 Nmin content layer 0-60cm
Nmin content layer 0-30cm
Includes mineralisation, N from
crop residues, climate
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KNS in cauliflower
TV =167 kg N/ha
60 kg N/ha in 0-30 cm layer
= N-advice 107 kg N/ha
TV =252 kg N/ha
Normal situation:
150 kg N/ha in 0-60 cm layer
= N-advice 102 kg N/ha
High mineralisation:
200 kg N/ha in 0-60 cm layer
= N-advice 52 kg N/ha
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KNS in early cauliflower
weeks after plant
N-uptake
cumulative N-uptake
Latent N
Rooting depth
Target value N(0-30)
Target value N(0-60)
TV with min. (0-60)
1
0
0
120
30
Early Cauliflower
2
3
4
5
5
10
15
25
5
15
30
55
120 120 120 120
30
30
30
30
6
45
100
80
30
7
45
145
80
30
8
40
185
80
30
9
10
195
80
60
10
5
200
80
60
280
252
280
252
225
197
180
152
135
107
95
67
85
57
275
247
Advice for whole period
265
237
250
222
Control N in soil
Mineralisation: standaard 0,8 kgN/ha/day
But lower in spring (soil temperature low)
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Principle KNS-system





Experience and trials with KNS in vegetables since ’90 at
station
Adaptations for specific cultures (eg early cauliflower), yield,
growing period
Farmers confident with KNS, could take samples themselves
to analyse by station: quick en cheap
2013: Sampling and advice obligated; samples must be taken
by lab: more expensive
2014: Agreement between experimental stations to use
adapted KNS-system for N-advice
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KNS-system on pilot farms



Project to compare KNS with fertilisation strategy farmer
15 fields in Flanders (2006-2009)
Comparison
Part of the field:
– Fertilisation according to KNS
– Goal: Minimum amount of leachable N
No yield/quality losses
Other part by farmer
– Usual fertilisation strategy
Farmer
KNS
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KNS-system on pilot farms
70%
45%
30%
20%
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KNS N-advice in cauliflower
Summary of N advices for cauliflower in 2013 (304 parcels)
adviced dose N
0 kgN/ha
1-50 kgN/ha
51-100 kgN/ha
101-150 kgN/ha
151-200 kgN/ha
201-225 kgN/ha
>225 kgN/ha
%
44,7
12,2
12,5
13,2
10,9
4,3
2,3
soil sampling
before planting > 2weeks
before planting < 2weeks
0-3weeks
4-7weeks
7-9weeks
10-11weeks
>11weeks
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%
3,6
40,5
10,9
20,1
14,5
1,0
9,5
KNS N-advice in cauliflower
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Difficulties with KNS
Mineralisation from soil
How many ?? kg N/ha/day
 Differences between fields
 History in use from organic matter
 Monitoring experiment on 15 blanco fields on farms,
measurements in soil april-october, 4 Years
 Range between 0,5 - 1,5 kg N/ha/day
→ regular soil sampling = getting idea of mineralisation
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Soil mineralisation
Nitrogen (kgN/ha)
Release of nitrogen, sandyloam soil 2% C by layers of 30cm
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Evolution of mineralisation 2008-2011
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Difficulties with KNS
Cauliflower residues in last culture
 Low nitrate residue at harvest
 High nitrate residue in oct-nov
 No green manures possible
Solutions?
Undersown of Italian ryegrass/rye?
– Sowing 4 weeks after planting
Incorporating residues after winter?
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Difficulties with KNS
Autumn 2013
Spring 2014
Uptake 60-90 kgN/ha by ryegrass
Best recovery after entering field
Further experiments necessary
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Conclusions KNS system





Important advice system for cauliflower, vegetables in
Flanders
Best combination between high production/quality and low
nitrate residue
No guaranty for threshold value nitrate residue (85 kgN-NO3/ha)
Correct estimation of mineralisation
How to manage crop residues in autumn. Undersown?
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Thank you for your attention!
Questions?
Joris De Nies
Proefstation voor de Groenteteelt
[email protected]
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