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Soil & Tillage Research 53 (2000) 137±144
The effects of crop rotation and fertilization on wheat productivity
in the Pampean semiarid region of Argentina
2. Nutrient balance, yield and grain quality
J.A. Galantinia, M.R. Landriscinib, J.O. Iglesiasc,
A.M. Miglierinac,*, R.A. Rosellb
a
ComisioÂn de Investigaciones Cientõ®cas (CIC), Departamento de AgronomõÂa, Universidad Nacional del Sur (UNS),
8000 BahõÂa Blanca, Argentina
b
Consejo Nacional de Investigaciones Cientõ®cas y TeÂcnicas (CONICET), Dpto de AgronomõÂa, UNS,
8000 BahõÂa Blanca, Argentina
c
Departamento de AgronomõÂa, UNS, 8000 BahõÂa Blanca, Argentina
Received 18 November 1997; received in revised form 4 June 1998; accepted 14 October 1999
Abstract
Wheat (Triticum aestivum L.) in the semiarid region of Argentina has often been grown as a low-input crop. Rainfall
scarcity and distribution are the main characteristics of the region. Consequently, a knowledge of the effect of different
management practices is the key to sustainable crop production. The objective of this work was to study the effect of 15 years
of different wheat management practices on plant nutrition, dry matter production and grain yield and quality. The treatments
were: continuous wheat (WW), wheat-grazing natural grasses (WG) and wheat±legume: [vetch (Vicia sativa L.) plus oat
(Avena sativa L.) or Triticale (Triticum aestivum L. Secale cereale L.)] (WL), with and without fertilizer (N ‡ P)
application. The WW and WL treatments involved annual tillage and a long fallow period (4±6 months) under stubble mulch,
and WG involved annual alternate tillage and a short fallow (1 month). The experiment was started in 1975 and the data
presented were obtained in 1989. Wheat yields were higher with the WW than with the WG rotation, but in both rotations
fertilization was required to obtain better grain quality (protein content higher than 11 per cent). The wheat±legume rotation
resulted in the highest yield, protein content, and better yield components. Fertilizer application did not increase dry matter
production but improved nutrient uptake and grain quality. Yield component differences could be attributed to water
availability due to different fallow length. The wheat±legume rotation seemed to be the best practice in the semiarid Pampean
region. # 2000 Elsevier Science B.V. All rights reserved.
Keywords: Wheat yield components; Grain quality; Crop rotation; Semiarid region; Rotation
*
Corresponding author. Tel.: ‡54-291-453-4775; fax: ‡54-291-459-5127.
E-mail addresses: [email protected] (J.A. Galantini), [email protected] (A.M. Miglierina).
0167-1987/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 1 6 7 - 1 9 8 7 ( 9 9 ) 0 0 0 9 7 - 5
138
J.A. Galantini et al. / Soil & Tillage Research 53 (2000) 137±144
1. Introduction
Wheat productivity components are affected by
physical, chemical and biological soil properties
and climatic conditions. In semiarid regions the
response to fertilizer application depends on amount
and distribution of precipitation.
To improve the limited possibilities of dryland
farming, it is essential to apply sustainable management practices on the land. Use of crop rotations with
legumes improves soil physical (Andriulo et al.,
1990a,b), chemical (Miglierina et al., 1995) and biological conditions, thereby enhancing nutrient availability and soil water contents (Loewy, 1987;
Galantini et al., 1992).
Wheat yield and protein contents have been
increased with N fertilization. However, increases
in the rate of N application may result in greater
severity of soil water de®cits under dryland farming. Winter wheat grown with water stress had
a shorter effective grain ®lling period and, consequently, lower kernel weight (Frederick and
Camberato, 1995).
Plant analysis is an important tool to establish the
nutritional needs of crops, but requires careful interpretation when using critical levels (Rosell et al.,
1992). As plant nutrient concentrations are changing
with the age of the plants, for diagnostic purpose it is
better to use the nutrient ratio that remains quite
constant throughout the plant cycle (Beau®ls, 1973).
These concepts are basic in Diagnosis and Recommendation Integrated System (DRIS) application
(Sumner, 1977). The DRIS proposed by Beau®ls
(1973) has been used to determine the balance of
N, P, K and S in wheat plants (Sumner, 1977). The
DRIS procedure was used to measure deviations of
actual nutrient concentration ratios in plant tissues
from the values of the same ratios previously established as reference values or norms. The DRIS international norms for N, P, and K, obtained by several
authors (Sumner, 1981; Beverly, 1993) have been
utilized. However, some researchers have suggested
that norms calculated from a local data base may
improve DRIS diagnosis (Dara et al., 1992). Besides,
the grain and straw analyses give complementary
information on the crop nutrition and the ef®ciency
use of the fertilizers (Martinez, 1987). Therefore, soil
and plant analyses as well as crop ®eld observations
provide good information for establishing the status of
the crop in the region.
The objective of this study was to evaluate the effect
of 15 years of different production systems and fertilization practices on crop nutritional balance, and on
the yield and quality of wheat in the semiarid Pampean
region.
2. Materials and methods
2.1. Experimental site
Field research was carried out at the INTA Agricultural Experimental Research Station, Bordenave,
Province of Buenos Aires, Argentina, located in the
Pampean semiarid region (638 01'W; 378 52'S). The
experiment was started in 1975, and plant samples
were taken in 1989, at the end of 15 years, when all
plots were seeded with wheat. The site is representative of the central±southern semiarid Pampean region.
The climate is temperate. Mean annual rainfall and
temperature are 654 mm and 158C, respectively. The
amounts of precipitation are higher in fall and spring
than in winter and summer (Fig. 1). Cereal water
requirements, calculated by FAO methodology (Paoloni and VaÂzquez, 1985), for Bordenave region are
presented in Fig. 1.
The main soil sub-group is an Entic Haplustoll
(FAO: Haplic Kastanozem), ®ne to medium sandy
loam, with slope of 0±1 per cent and a caliche (calcareous) layer located at a depth between 0.8 and 1 m.
The three crop rotations studied, fully described in
Miglierina et al. (1999), are:
WW, annually cropped continuous wheat;
WG, wheat and cattle grazing natural grasses,
alternatively one year each; and
WL, 2 years wheat and 2 years of a mixture of vetch
plus oats or triticale for pasture grazed winter crops.
The WW and WL rotations had 4±6 months of
fallow with residues of the previous crop with
mechanical weed control and the WG had a short
(1 month) fallow.
Imposed on the three rotation systems areas were
non-fertilized (nf) and annually fertilized (f) treatment
plots, with 64 kg N haÿ1 as urea and 16 kg P haÿ1 as
diammonium phosphate applied at seeding time
(June).
J.A. Galantini et al. / Soil & Tillage Research 53 (2000) 137±144
139
Fig. 1. Mean monthly (1928±1992) and study year (1989) precipitation and cereal water requirement (CWR) at Bordenave Experimental
Station, Argentina.
2.2. Plant analysis
Total aerial dry matter (TADM) was determined at
stem elongation (®rst node visible, Feekes scale No. 6,
Miller, 1992), during September, and at maturity
(Feekes No. 11.4), beginning of December.
The samples were washed with distilled water, oven
dried at 608C and ground (<40 mesh). Nitrogen (N)
was determined by semi-micro Kjeldahl (Bremner and
Mulvaney, 1982); total phosphorus (P) and potassium
(K) were obtained by the digesting samples with a
perchloric±nitric acid mixture (Johnson and Ulrich,
1959) and determined by ammonium vanadate colorimetry (Murphy and Riley, 1962) and ¯ame photometry, respectively.
Grain protein, on a 13.5 per cent kernel moisture
basis, was obtained with a near infrared re¯ectance
(NIR) system (Technicom Infraalyzer 400, Technicom
Industrial Systems, USA). Gluten was determined
with a Glutomatic analyzer (Perten Instruments,
AB. Sweden), and the results are presented on a moist
and oven-dry (1058C) basis. Sulfur determination was
made with a LECO S-Analyzer (LECO Co., St.
Joseph, MI, USA). Yield components such as spikes
per square meter, kernels per spike and kernel weight
were also obtained.
2.3. DRIS analysis
Diagnosis and recommendation integrated system
(DRIS) method was applied to the determination of N,
P, and K nutritional balance of the wheat at stem
elongation. DRIS indices and the element sequence
of the nutritional balance were obtained by using
Beau®ls (1973) relationships as follows:
N index ˆ ‰ f …N : P† ‡ f …N : K†Š : X
P index ˆ ‰ÿf …N : P†ÿf …K : P†Š : X
and
K index ˆ ‰ f …K : P†ÿf …N : K†Š : X
where X ˆ number of functions in the numerator (in
this case 2).
For the N index:
N:P
1000
when N : P > n : p;
ÿ1
f …N : P† ˆ
n:p
CV
or
h n : p i 1000
f …N : P† ˆ 1ÿ
N:P
CV
when N : P < n : p;
where N:P is the actual value of the ratio of N and P
(g kgÿ1) in the plant being diagnosed; n:p the value of
the reference norm from high-yielding wheat plants
and CV the coef®cient of variation of this norm's
population.
The norms are utilized in empirically derived equations that result in a set of indices denoting suf®ciency
or de®ciency of each nutrient studied. The lowest (or
more negative) DRIS index indicates the most de®cient or yield-limiting nutrient in comparison with the
other tested elements. A DRIS index equal to zero
140
J.A. Galantini et al. / Soil & Tillage Research 53 (2000) 137±144
The P contents were high in plants from all treatment plots, exceeding the crop needs (Westfall et al.,
1990). The WW plots had the lowest plant P content.
Annual fertilization signi®cantly increased P concentration in WW and WG, but not in WL rotation plots.
Plant K concentrations were high (Westfall et al.,
1990) with all treatments; however, a signi®cant
increase was observed in fertilized WL, WW and
WG plots. In non-fertilized WW and WG plots, no
differences were observed in early nutrient absorption
(Table 1) and dry matter production (Table 2) although
they had different length fallow periods.
In general, the application of N and P increased
NPK uptake and TADM production. The WL rotation
resulted in the largest TADM production and NPK
accumulation. The effect of the legume in the WL
rotation was similar to fertilizer application in WW
and WG rotations (Table 2). This supports the important role of legume species as a partial substitute for
fertilizers (Campbell et al., 1992).
means that the element is present in quantity associated with a high-yielding crop. The sum of elemental
DRIS indices (NBI) equals zero; consequently, the
assessment of the relative balance among diagnosed
nutrients is also possible.
2.4. Data analysis
The experiment had a randomized complete block
design and a split-plot arrangement with three replications. The three crop rotations were assigned to the
main plots and fertilizer applied to sub-plots. Data
were analyzed by the ANOVA. Tukey's test was used
to separate the mean values.
3. Results and discussion
3.1. Plant nutrient concentration and absorption
The WG rotation, with the shortest fallow period,
did not increase dry matter production and nutrient
absorption at stem elongation (Tables 1 and 2) as
compared with the WW rotation, but stressed the crop
during the grain ®lling stage (Table 3).
Wheat plants from the legume and fertilized rotation plots had high N contents during elongation
(Table 1), but the response to fertilization was signi®cant only for the WW rotation.
3.2. DRIS indices and nutritional balance
A DRIS index from ÿ15 to ‡15 indicates good
nutrient balance in the plant (Kelling and Schulte,
1986). In all cases N was the most de®cient nutrient
(indices lower than ÿ25), K values were around zero
and P values showed an excess (more than ‡25) at
stem elongation (Table 1). The high NBI indicated a
Table 1
Plant N, P and K concentration (g kgÿ1), DRIS index, nutritional balance index (NBI) and nutritional balance in wheat at stem elongation in
three crop rotationsa
Parameter
WW
WG
WL
nf
f
nf
f
nf
f
Concentration
N
P
K
DRIS index
N
P
K
30.3 c
3.l c
42.6 c
34.3 ab
3.5 b
52.5 ab
32.7 b
3.5 b
42.0 c
34.5 ab
3.9 a
49.8 b
34.2 ab
3.4 bc
51.1 b
35.6 a
3.6 ab
57.3 a
ÿ97
97
0
ÿ98
90
8
ÿ93
106
ÿ13
ÿ103
107
ÿ4
ÿ93
86
7
ÿ99
86
13
NBI
194
196
212
214
186
198
Nutritional balance
N>K>P
N>K>P
N>K>P
N>K>P
N>K>P
N>K>P
a
WW: continuous wheat; WG: 1 year wheat ÿ 1 year grazing natural grasses; WL: 2 years wheat ÿ 2 years legume and grass mixture; nf:
non-fertilized and f: fertilized. Different letters in a row indicate signi®cant differences between treatments (p < 0.05, Tukey's test).
J.A. Galantini et al. / Soil & Tillage Research 53 (2000) 137±144
141
Table 2
Total aerial dry matter (TADM) production and N, P. and K contents (kg haÿ1) at stem elongation in different wheat crop rotationsa
Parameters
TADM
N
P
K
a
WW
WG
WL
nf
f
nf
f
nf
f
1140 c
33.4 c
3.6 c
49.2 c
1960 ab
67.3 b
6.9 b
103.1 b
1230 c
40.2 c
4.3 c
51.6 c
1960 b
67.l b
7.6 b
97.3 b
1930 ab
65.9 b
6.5 b
98.4 b
2440 a
86.7 a
8.9 a
139.3 a
The column headings have the same meaning as in Table 1.
Table 3
Dry matter, grain, straw and protein yields (kg haÿ1) in wheat from different crop rotationsa
WW
WG
nf
Grain
Straw
Total dry matter
Protein
a
2920
6260
9180
290
f
c
cd
c
cd
3580
7340
10920
420
WL
nf
b
bc
bc
b
2190
4990
7180
240
f
d
d
d
d
3060
6290
9340
360
c
cd
c
bc
nf
f
4110 a
85l0 ab
12620 ab
520 a
4050
8910
12960
560
a
a
a
a
The column headings have the same meaning as in Table 1.
nutritional imbalance with all treatments, regardless of
fertilizer application and crop rotation.
3.3. Yield components
The spike number per unit area was greatest for
wheat on WL rotation plots, and similar on WW and
WG plots (Table 4). The number of spikelets per spike
were similar with all treatments. Only the differences
between the numbers for the WWf, WGnf and WLnf
treatments were signi®cant. When water became limiting, the large spike number for the WWf treatment
resulted in small spikelets (Evans and Wardlaw, 1976).
The weight of kernels was similar with all treatments, except that the WWnf treatment resulted in a
higher value due to the low number of kernels per
square meter.
Fertilization increased plant height in the WW
and WG rotation plots, but no response was found
in the WL rotation plots due to their inherent fertility
(Table 4).
The close relationship between yield components
and rainfall distribution is well known. Water availability, accumulated during the fallow period and
rainfall, was higher than plant needs during the early
stage of growth (Fig. 1). For this reason the increased
number of spikes per square meter can be attributed to
the fertilizer application or crop rotation. Later on,
when water became a limiting factor, differences in
the number of spikelets per spike were observed.
Table 4
Yield components and plant height in wheat from different crop rotationsa
Parameters
ÿ2
Spike (m )
Kernel (spikeÿ1)
Kernel weight (mg kernelÿ1)
Plant height (cm)
a
WW
WG
WL
nf
f
nf
f
nf
f
242 c
19.9 ab
37.6 a
84.5 c
445 ab
18.6 b
35.6 ab
104.0 a
230 c
20.6 a
35.0 b
78.8 c
379 b
19.9 ab
33.8 b
94.2 b
429 ab
20.0 ab
34.0 b
103.2 a
472 a
19.7 ab
34.9 b
102.9 a
The column headings have the same meaning as in Table 1.
142
J.A. Galantini et al. / Soil & Tillage Research 53 (2000) 137±144
Grain ®lling and TADM production were affected by
water stress.
3.4. Plant productivity
The WL rotation resulted in the highest grain, straw,
and protein yields (Table 3). For the WW and WG
rotations straw and protein production were similar
but lower than for WL, and their grain yields were
2920, 2190 and 4110 kg haÿ1, respectively. This may
be attributed to the high fertility, mainly P and water
availability (Miglierina et al., 1999), generated by the
different fallow length.
Fertilization produced a wheat yield increase in
WW and WG but not in the WL plots. Grain yields
with the WL rotation were high compared with the
average for the region (ca. 1200 kg hÿ1). Wheat water
de®cits during the reproductive stages (October±
November) (Fig. 1) are usually observed in this semiarid region, which impair nutrient uptake and fertilizer
response. Previously, it had been observed that the
incorporation of legumes in the crop rotation
improved wheat yield and quality (Galantini et al.,
1992) but, under low rainfall, such practice may be
detrimental to grain production (Loewy, 1987).
With the non-fertilized treatments, wheat N uptake
was higher in WL than in WW and WG rotation plots
(Table 5). The long fallow period with WW did not
increase the N harvested with respect to WG.
Fertilization only increased plant N in rotations
without legume, due to higher grain N content (Table
5). Other authors (e.g., Martinez, 1987) found similar
results, the fertilization of continuous wheat resulted
in a higher N recovery, grain yield and protein content
than the WGf treatment (Table 3). Rainfall timing and
amount were important factors for the growth of wheat
(Sanchez de la Puente and Belda, 1992).
The WW rotation resulted in similar soil porosity
distribution and higher soil N content but it did
not show a response to fertilizer application with
respect to the WG rotation. This behavior may be
attributed to the short fallow period used with this
treatment. These results, as previously reported
(Galantini et al., 1992), showed that fertilizer application can be partially replaced by legume crops in
wheat rotations.
The highest straw N content occurred with the WL
rotation. When left on the ®eld it will be incorporated
into the labile organic matter fraction and recycled,
reducing the N needs in the following crop (LoÂpezBellido et al., 1996).
Protein contents in grain were lower than 11 per
cent with the WW and WG non-fertilized rotations,
and these were signi®cantly lower than in WL plots
(Table 6). Other authors (e.g., Campbell et al., 1992)
found that non-fertilized continuous wheat produced
low protein content grain. Previous studies in the
Pampean semiarid region (Galantini et al., 1992)
showed that it was necessary to apply N fertilizers
to maintain protein contents of 11 per cent or higher.
Complementary information about grain quality can
be obtained from gluten contents and N:S ratios since
the gluten and protein contents are closely related.
When N:S ratios are greater than 17 and grain S
concentrations are lower than 1 g kgÿ1 a response
to fertilizer application is expected (Withers et al.,
Table 5
Nitrogen concentration (g kgÿ1) and yield (kg haÿ1) in grain, straw and total above ground dry matter in wheat from different crop rotationsa
Parameters
WW
nf
Grain
Concentration
Yield
Straw
Concentration
Yield
Total above ground dry matter
Yield
a
WG
f
WL
nf
f
nf
f
25.8 b
105.8 a
27.8 a
112.5 a
20.5 d
59.9 cd
24.l b
86.4 b
22.l cd
48.3 d
23.9 bc
73.2 bc
2.30 c
14.5 c
2.56 bc
18.7 c
2.94 bc
14.2 c
2.92 bc
18.3 c
62.5 d
91.5 bc
74.4 cd
l05.1 b
The column headings have the same meaning as in Table 1.
3.24 ab
27.4 b
133.2 a
3.81 a
34.2 a
146.7 a
J.A. Galantini et al. / Soil & Tillage Research 53 (2000) 137±144
143
Table 6
Wheat grain protein and gluten content (per cent) and nitrogen:sulfur ratio (N:S) for different crop rotationsa
Parameters
Protein
Gluten
Wet basis
Dry basis
N:S ratio
a
WW
WG
WL
nf
f
nf
f
nf
f
10.1 d
11.9 b
10.9 cd
11.8 bc
12.7 b
13.7 a
15.2 c
5.1 c
22.3 b
7.3 b
17.2 c
5.8 c
22.7 b
7.5 b
25.7 b
8.3 b
30.7 a
10.1 a
12.3
10.3
13.0
13.1
7.3
9.5
The column headings have the same meaning as in Table 1.
1995). An N:S ratio of 13 or lower indicated adequate
S contents (Table 6).
4. Conclusions
This study shows the effects of 15 years of wheat
rotations with data con®ned to only one year (1989). In
this context, the wheat±legume rotation resulted in
higher yields and protein contents, and better yield
components than the other two rotations (WW and
WG). Fertilizer applications improved grain protein
and N straw content, but had little effect on yield in
WL plots. The WW and WG rotations resulted in
intermediate and the lowest yield components, respectively. Crops required N fertilizer applications to
achieve acceptable grain production and protein
contents.
The treatment involving wheat and annual legumes
(WL) did not require fertilizer applications to achieve
the potential crop yields of the semiarid Pampean
region and this rotation is considered to be the more
ecological and sustainable system for the low rainfall
farms of this region. However, in view of the dominant
effect of seasonal weather, especially rainfall, on crop
responses to rotation and fertilization, the results of
this study must be interpreted with caution.
Acknowledgements
The authors wish to thank the institutions that
provided funds and personnel for this research: Consejo Nacional de Investigaciones Cientõ®cas y TeÂcnicas (CONICET). ComisioÂn de Investigaciones
Cientõ®cas (CIC), La Plata; EstacioÂn Experimental
Agropecuaria INTA, Bordenave; CaÂmara Arbitral de
Cereales, BahõÂa Blanca.
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