Transcript Nutrient management adaptation for dryland maize yields and water

APEC International Conference on Natural Resources and Infrastructure Management for Agriculture
Nutrient management adaptation for dryland
maize yields and water use efficiency to longterm rainfall variability in China
Prof. Dr. Cai Dianxiong
Institute of Agricultural Resources and
Regional Planning ,CAAS
Beijing,100081,China
[email protected]
August, 2012 in Bangkok
1. Introduction
 Northern China has a large region of dryland farming, which accounts for
about 55% of the nation’s total cultivated land. Water scarcity and a large
variation in inter-annual and intra-annual rainfall are the main constraints
to rainfed crop production, causing low and unstable food production.
 Erratic rainfall is a cause of soil and water losses on sloping lands during
the summer rainy season and seasonal drought in winter and spring. The
wind exacerbates soil drought and causes a reduction in both spring maize
seedling emergence and winter wheat growth during most years.
 The dryland areas of northern China are highly important for providing
food and feed to the growing human and animal populations. Maize
accounts for 22% of the total area of food crops, and 26% of the total food
production in China .
 The effects are exaggerated by the current practices of removing crop
residues from the field after harvest, to leave the ploughed soil bare during
winter, and to plough the soil again in spring after fertiliser application (for
spring maize), and thus cause a reduction in spring crop seedling
emergence.
 In the dryland areas of northern China, crop yield responses to fertiliser
application are quite low and variable, due to unbalanced fertiliser use
and crop residue removal under traditional tillage systems resulting in
inefficiencies of both water use and fertiliser use, and low economical
return to farmers.
 Soil conservation and improved nutrient management practices are
gaining interest of Chinese research and policy communities.
 Reduced tillage was introduced in the study area in the early 1990s and it
showed to be highly effective in decreasing soil drying and wind erosion,
especially with integrated conservation tillage and improved nutrient
management practices (Wang et al., 2007).
 The practice required that fertilisers, crop residues and manure are
applied in autumn prior to ploughing, approximately 6 months before
maize is seeded. Applying fertilisers long before the crop growing season
is only feasible in dry conditions where nutrient losses are minimal.
Many of the Challenges for dryland agriculture are
Intensification of Limits that We Currently Address
•
•
•
•
•
Low and highly variable moisture
Severe weather events
Periodic drought
Unreasonable nutrient and water use in some areas
Wind and water erosion
Increased soil water and nutrient use efficiency help to
address these challenges
To optimize the combined application of NP fertilisers,
maize stover and cattle manure under reduced tillage
practices may is one way to face of Challenges of Dryland
Farming today.
材料与方法
2. Materials and
methods
2.1. Site description
The ongoing long-term field experiment started in 1992 at the Dryland
Farming Experimental Station in Shouyang, Shanxi province (112–113◦E,
37–38◦N) in northern China. The area has a mean altitude of 1100m
above sea level.
Shouyang county
(Shanxi province)
5
2012.06
Table 1. Site description
Parameters
PPT
PET
AMT
RH
Soil
Values
= 560 - 864 mm
= 1662 to - 1852 mm
= 7.4℃ (- 23.5 - 43.7 °C)
= ± 65%..
= sandy loam cinnamon soil,
( classified as Calcaric-Fluvic Cambisols )
soil pH
= 7.9
SOC
=15 g kg−1
Soil organic N (SON) = 1.0 g kg−1
P-Olsen
= 7.3 mgkg−1
NH4OAc extractable K = 84mgkg−1
Spring corn Variety = Jindan 48
2.2. Experimental design
The experiment was set up according to an incomplete,
optimal design (Xu, 1988) with 3 factors (NP fertiliser, maize
stover and cattle manure) at five levels and 12 treatments
(see Table 2), including a control treatment and two
replications. This experimental design allows the use of a
minimal set of factors of the variance–covariance matrix and
provides a maximal efficiency of the experiment.
An important condition is that within the range of
applications chosen, the optimum responses are found. The
procedures of this design are explained in Khuri and Cornell
(1987).
Table 2. Experiment treatments on combined applications of
NP fertiliser, maize stover and cattle manure.
Treatment
Fertiliser (kg ha−1)
Stover (kg ha−1)
Manure (kg ha−1)
1
2
3
4
5
6
7
8
9
10
11
12
105
105
31
179
31
179
210
0
105
105
105
0
3000
3000
879
879
5121
5121
3000
3000
6000
0
3000
0
6000
0
4500
4500
4500
4500
1500
1500
1500
1500
3000
0
Note: Fertiliser N:P2O5 = 1:1.
2.3. Methods
Plots (6m×6m) were laid down randomly in replicates.
The N and P fertilisers were urea (46% N) and superphosphate (7% P) in a
ratio of N to P of 1:0.44.
 Maize stover and cattle manure were obtained from local farms. The
weighted mean contents of organic matter, total N, total P (as P) and total K
were 75%, 0.63%, 0.039% and 0.72% for maize stover (ratio of N:P:K =
100:6:114) and 36%, 0.96%, 0.17% and 0.74% for cattle manure (ratio of
N:P:K = 100:18:77), respectively.
Maize stover (S), cattle manure (M) and
fertilisers (F) were broadcast and incorporated
into the soil after maize harvest in the fall by
ploughing (20cm deep) with conservation tillage.
Grain yield and crop residues were determined
by harvesting the centre 1.8m×2.1m of the plots.
Soil moisture determination
研究思路与技术路线
Soil temperature measuring
Soil carbon emission measuring
2012.06
Yield measuring
12
2.4. Data processing and statistical analysis
Apparent water use or apparent evapotranspiration (ET, in mm) was
calculated from the change in soil water contents between the beginning
of the growing season at sowing (SWS, in mm) and the end of the
growing season at crop harvest (SWH, in mm) plus rainfall received
during the growing season (GSR), viz.
ET = (SWS − SWH) + GSR
(1)
Hence, we assumed that there were no losses via deep drainage and
runoff during the growing season. Apparent water use efficiency (WUE, in
kg ha−1mm−1) was calculated from grain yield (GY) and ET, according to
WUE = GY/ET
(2)
Statistical analyses were done using GLM, REG and RSREG procedures
of the SAS Institute Inc. (2004). The data were subjected to an analysis of
variance using the GLM procedure. The mean pairwise comparison was
based on the Duncan test at the 0.05 probability level (at P≤0.05). In
addition, stepwise multivariate regression analyses were carried out.
Linear and nonlinear (parabolic) statistical models were fitted to describe
the relationships between GY and added N via fertiliser, crop residues
and manure applications, and GSR and SWS.
Methodology
Water balance equation
ΔS  P  I  ET  R  D  Li  Lo
Trime-FM3-Tubeprobe
(TDR)
Methodology
Water balance equation
ΔS  P  I  ET  R  D  Li  Lo
Tipping-bucket rain
gauge
Datalogger
Flume + discharge gauge
+ drums
Methodology
Water balance equation
ΔS  P  I  ET  R  D  Li  Lo
D  qzr t
1
qzr
dH
  K ( )
dz
Ks tension infiltrometer
MRC sand box/pressure chamber
H
tensiometers (Hg)
Mualem-van Genuchten (1980)
Methodology
Water balance equation
ΔS  P  I  ET  R  D  Li  Lo
D  qzr t
1
dH
qzr   K ( )
dz
Mualem-van Genuchten (1980)
2
Plane of zero flux method
qzr  S t
1
Methodology
Water balance equation
ΔS  P  I  ET  R  D  Li  Lo
Equipotential lines
5 sets of tensiometers 5 m apart
3. Results
3.1. Variation in rainfall and soil water
Fig. 1. Annual growing season rainfall (GSR), average amounts of
soil water in the upper 2m at sowing (SWS), and apparent water
use (ET), in Shouyang during the experimental period 1993–2007.
3.2. Mean grain yield and water use efficiency
Table 3 Effects of combined applications of NP fertiliser (F), maize stover
(S) and manure (M) on grain yield (GY), water use efficiency (WUE) and
evapotranspiration (ET) per treatment, averaged over the whole
experimental period (1993–2007). Data from 0 to 200cm soil depth.
Tmt.
12
8
3
10
5
7
4
2
6
11
1
9
F
(kg ha−1)
0
0
31
105
31
210
179
105
179
105
105
105
S
(kg ha−1)
0
3000
879
0
5121
3000
879
3000
5121
3000
3000
6000
M
(kg ha−1)
0
1500
4500
1500
4500
1500
4500
0
4500
3000
6000
1500
GY
(kg ha−1)
4233 f
4989 e
5851 d
6256 cd
6396 c
6438 c
6459 c
6531 bc
6593 bc
6729 abc
7050
7230 a
WUE
(kg ha−1 mm−1)
11.1 f
13.0 e
14.5 d
15.5 cd
16.6 bc
16.3 c
16.2 c
16.4 c
16.7 bc
16.7 bc
17.9 ab
18.7 a
ET
(mm)
391.7 b
413.0 a
401.6 ab
399.6 ab
398.3 ab
405.9 ab
407.9 ab
407.5 ab
407.1 ab
409.5 a
407.1 ab
396.9 ab
Note: Values with the same letter within a column are not significantly different at 5%
level using the Duncan test of SAS.
3.3. Annual variations in grain yields
Fig. 2. Effects of combined applications of NP fertiliser (F), maize stover (S) and
manure (M) on grain yield (GY), in the period 1993–2007. Results are shown for the
treatments 1, 2, 7, 8, 9, 10 and 12 (the control).
Table 4. Coefficients of the regression models for grain yield (GY) and water
use efficiency (WUE) as function of NP fertiliser (both linear (Fertiliser) and
quadratic (Fsq)), maize stover, and manure, soil water at sowing (SWS) and
rainfall during the periods April–June (R(A–J)), July (R(J)) and August–October
(R(A–O)), for the whole experimental period 1993–2007. Data from 0 to
200cm soil depth.
Dependent
variablen
Param.a
Intercept
Fertiliser
Stover
Manure
R(A–J)
R(J)
R(A–O)
SWS
Fsq
GY
PE
−4700
29.4
0.14
0.08
4.7
22.9
3.1
14.7
−0.11
R2 = 0.60,
N= 164
SE
1091
5.3
0.06
0.06
2.7
2.4
1.4
2.6
0.03
t-Value
−4.3
5.5
2.4
1.4
1.7
9.6
2.3
5.7
−4.44
Pr > |t|
<0.0001
<0.0001
0.017
0.16
0.08
<0.0001
0.02
WUE
PE
5.99
0.0585
0.0005
0.0002
0.0002
0.022
−0.027
0.022
−0.0002
R2 = 0.46,
N= 164
SE
3.57
0.0166
0.0002
0.0002
0.0083
0.008
0.004
0.009
0.0001
t-Value
1.68
3.51
2.95
1.17
0.02
2.85
−6.39
2.45
−2.73
Pr > |t|
0.096
0.0006
0.004
0.243
0.98
0.005
<0.0001
0.015
0.007
a PE:
<0.0001 <0.0001
parameter estimate; SE: standard error; Pr: probability-value (P-value).
3.4. Annual variations in water use efficiency
Fig. 3. Relationships between grain yield and apparent water us for all
experimental years and treatments. The lowest and highest water use
efficiencies are indicated by the arrows.
4. Discussions and conclusions
4.1. Grain yield response to rainfall and nutrient
management
Grain yields were greatly influenced by SWS and GSR, causing differences
between years in the order of 200–300% (e.g. between 1994 and 2007).
 GY was limited by the availability of nutrients in the soil. Added NP
fertiliser, maize stover and cattle manure increased GY, but effects of NP
fertiliser, cattle manure and maize stover were different.
Although added NP fertiliser, maize stover and cattle manure as such
increased GY, a balanced combination gave the highest mean yield, about
60% increase relative to the control treatment.
fertilisation effects were smaller than rainfall effects.
Effects on GY appeared to increase over time, but could mainly be
attributed to the fact that GY of the control treatment declined due to
nutrient depletion of the soil.
Grain yields in some years may also have been affected by diseases (mainly
head smut). In this respect, our findings are confirmed by Li et al. (2003) and
Bai et al. (2006) who also pointed to decreasing GSR, soil nutrient depletion
and diseases as major causes for declining yields.
4.2.Water use efficiency response to rainfall and nutrient management
Fig. 4. Calculated relationships (1) between water use efficiency (WUE) and added stover, manure
and N fertiliser (upper panels), (2) between WUE and added stover and N fertiliser, and soil water at
sowing (SWS) (middle panels), and (3) between WUE and added stover and N fertiliser, and rainfall in
July (lower panels), using the equations presented in Table 4
4.2. Water use efficiency response to rainfall and
nutrient management
 Differences in WUE were much larger between years than between
treatments (Fig. 4).
The major factors for explaining WUE differences are: the distribution of
the rainfall over the growing season and N availability, particularly soil
water at sowing (SWS) and rainfall during tasseling (Table 4).
In Fig. 4, the potential increase of WUE through improved nutrient
management is shown. WUE is presented as a function of added N fertiliser
(N), and stover (S) with resp. cattle manure, SWS and July rainfall.
Clearly, when calculated as an average over all years, WUE is highest at a
(modest) N fertiliser input of about 100 kg ha−1 (WUEN100), and (Fig. 4,
top) there is an additional positive effect of stover.
Increasing manure inputs from 0 to 6000 kg ha−1, increases WUE/N100
from about 14 to 15 kg ha−1mm−1 without stover, and from about 17 to 18
kg ha−1mm−1 with S = 6000 kg ha−1. A rise of SWS from 300 to 500mm, will
increase WUE/N100 from about 13 to 17 kg ha−1mm−1 without stover, and
from about 16 to 20 kg ha−1mm−1 with S = 6000 kg ha−1 (Fig. 4, centre).
Higher July rainfall (rising from 50 to 200mm; Fig. 4, bottom), has a similar
effect.
For rainfed areas, nutrient management should respond to such variable
conditions, targeted to the need of the growing crop, in a way commonly
termed as ‘response farming’ (Stewart, 1991). The concept of ‘response
nutrient management’, such as split applications, provides practical guidelines
for improving nutrient management under the variable rainfall conditions. Split
application of N fertiliser is a well-established management strategy to improve
the N use efficiency of cereal crops (e.g. Schroder et al., 2000; Pattey et al.,
2001; Angás et al., 2006).
It is recommended to apply about half or two-thirds of the recommended
total N dose at sowing and the supplement after emergence of the crop. The
supplemental N should depend on rainfall conditions and the N status of the
soil or crop (Schroder et al., 2000), and in dry years, supplemental N should not
be applied (Angás et al., 2006).
When applied under the conditions of Shouyang, the first N dressing (up to
100 kg ha−1, depending on stover and manure applications) should be applied
after harvest (before ploughing), as in the current experiment. A possible
second N dressing (up to 50 kg ha−1) may be applied at the 4–6 leaves stage,
depending on early season rainfall and the N status of the soil (Schroder et al.,
2000; Dobermann and Cassman, 2002). The feasibility of such split application
technology in practice needs to be tested further.
4.3. Conclusions
The results of this long-term field experiment in Shouyang of Shanxin in
northern China show that balanced combinations of stover (3000–6000 kg),
manure (1500–6000 kg) and NP fertilizer (105 kg) gave the highest maize
yield and hence WUE. It is suggested that 100 kgN per ha should be a best
choice, to be adapted according to availability of stover and manure.
Nutrient management under the rainfed conditions requires rainfall to be
taken into account in a dynamic approach to explain the strong interactions
between GSR and the effects of NP fertiliser, stover and manure.
The huge annual variations in grain yields and WUE indicate that there is
scope for improvement of water use efficiency by split applications. The
concept of ‘response nutrient management’, being an integral part of the
‘response farming’ is applicable to the variable rainfall conditions of the
drought-prone area for contributions to high crop yields.
For further improving water use efficiencies, the partitioning of basal and
supplemental N dressings need further examination for the variable rainfall
conditions of dry land areas in northern China.