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Contents
Water-fertilizer Coupling Model for
Cotton Production under Drip Irrigation
with Plastic Film Mulching in Xinjiang,
China

Introduction

Objectives

Data sources and methods

Results and analysis

Conclusion
Wei Xiuju
Chinese Academy of Agricultural Engineering
2016.11
Introduction: location, climate
Xinjiang
Research
area
Xinjiang
Introduction: Cotton production
importance
 A main cotton production area with
high-quality cotton , producing 3/5
cotton yield in China, accounts for
1/9 of the world’s yield, in 2015.
------ Longitude and latitude
73°40‘-96°23'E
34°25‘-49°10'N
------ Inland arid and semiarid
region: rare rainfall, annually150
mm (≤100 mm during growing
season) and strong
evaporation , annually 15003000 mm
------A typical irrigation agricultural
area
 Local people’s lives heavily on
cotton production. Cotton income
accounts for 40% of the local
peasant’s total . Cotton production is
of significant economy.
 Enough water supply is required for maintaining and increasing
cotton yield in Xinjiang
Introduction ：water scarity
Introduction: low WUE
 According to 《National Water Resources Allocation Plan》, the total
water resources in Xinjiang is 52 billion m3 in 2020. However, the
water consumption is 62 billion m3 in 2014, which is 10 billion m3
higher than the plan. –Large shortage
Low irrigation water use efficiency:
0.51 in 2014, about 60% of the developed country
Irrigation
 Xinjiang agriculture water rate is required to decrease from 95.6% to
90% of the total by 2020.
– Serious water resource shortage
condition
in Xinjiang
Irrigation method: conventional irrigation (eg. flooding,
border irrigation), membrane irrigation (water flow through
film to plant root), micro-irrigation(eg. irrigation with film mulching,
irrigation under pressure), spray irrigation. Drip irrigation under film
mulching saves water by 40%-50% and increases cotton seed
yield by 20%. It is a promising water-saving irrigation technology.
Low irrigation area with high efficiently water-saving
technology: By 2014, only 39.2% of the total irrigation area.
Can we maintain or increase cotton yield
under the background of serious water shortage in Xinjiang?
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Introduction: Do large area yield
model establish possible?
Introduction:Summary
 Researches showed that the cotton yield is affected by temperature,
cotton variety, and others.. For a certain region and cotton variety,
water and fertilizer-N show great affect.
 Some researchers built water-N coupling model for cotton yield
estimation based on plot experimental data.
 Arid Xinjiang of China is a main cotton producing area
 Under water, fertilizer-N and cotton variety certained, drip irrigation with plastic
film are consider to related to the potential yield
 Researches yield rich experimental data
 Rich experimental data on cotton yield affected by nitrogen and
water in irrigation under plastic film-mulching in Xinjiang.
Can we use these valuable data to
Cotton yield water-fertilizer coupling modle built based on
build a coupling modle for cotton yield at large scale for Xinjiang?
rich experimental data
Objectives
Data sources
Paper Database
To build cotton yield model under drip irrigation with
Literature
search
64 papers
plastic film mulching from a large scale in Xinjiang
Selecting
based on published data.
216 data groups
Study area: Xinjiang, China
Drip irrigation method: under plastic
film mulching
Clear information on place, year,
cotton variety, fertilizer-N application
rate, irrigation water amount, etc
Model establishment
Data sources
Data summary
Table 1 Data statistics
Parameter
Description
loam, sandy soil, silt clay soil
Soil texture
19 known variety
Cotton variety
>10oC cumulative temp./℃ 3450-4500
Parameter
Description
Experimental year
1998-2015
Annual rainfall/mm
20-280
Fertilizer N rate/(kg hm-2)
0-900
Organic matter/%
0.13-3
Irrigation amount/mm
60-675
pH value
7.4-8.8
Irrigation period/d
2-16
Plant density/(plant hm-2)
135000-290000
Cotton seed yield/(kg hm-2)
977-8290
Description of datasets
Research area is classified by northern and southern Xinjiang.
Data group for northern and southern Xinjiang is 147and 58
 Xinluzao and Xinluzhong are main cotton varieties for northern
and southern Xinjiang, respectively.
Table 2 Cotton variety and the corresponding data group
Region
Cotton Variety
Northern
301,81-3,Biaoza A1,Huiyuan 710,Paotai; Xinluzao No. 13, 1, 5, 10, 3, 1,1
Xinjiang
29,33,710,7,9, Zhongmiansuo 49, unknown
Southern
Xinluzhong No. 21, 26; Xinluzao No. 43, Hybrid cotton 6, 27, 4, 5, 3, 6,18
Xinjiang
mianzaofeng, Bamian No. 3, Xinhai No. 21, unknown
Data group
1, 38, 2, 24, 9, 9, 6
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Methods: Water-N coupling model establishment method
Table 3 Correlation analysis between factors and cotton yield in Xinjiang
Model establishment flow
216 Classified
by region
data
groups
147 group
(northern
Xinjiang)
Results-1
Selected
by cotton
variety
69 group
(southern
Xinjiang)
Selected
by cotton
variety
73
group
54
group
Random
Classification
N-Model
19
group
Random
Classific
33 -ation
group
23
group
Variable
yield
Cotton variety
Fertilizer-N
application
Irrigation amount
-0.83**
Fertilizer-N
application
-0.27*
Irrigation amount
-0.41**
0.39**
0.17
0.67**
0.17
Note: **，P<0.01; *，P<0.05
S-Model
10
group
Water-N coupling model: y=aW2+bF2+cW+dF+eWF +f
 Cotton yield is extremely significantly correlated with cotton variety,
fertilizer-N, and irrigation amount.
 Cotton variety is significantly correlated with fertilizer-N, and irrigation
W is irrigation amount, F is fertilizer-N application rate.
amount. Thus, cotton variety affects water-N coupling model establishement.
Model evaluation: R2, root mean square of error(RMSE), normalized root mean
square of error (nRMSE), concordance index(d)
Results-2:Model for Southern Xinjiang
5000
4000
Model
establishment
3000
2000
1000
1:1线1:1 line
6000
5000
4000
Model
validation
3000
2000
1000
1:1线1:1 line
0
0
0
1000 2000 3000 4000 5000 6000 7000
Measured value/(kg hm-2)
7000
8000
Y=-2872.95+11.33W+17.44F
7000
1:1线1:1 line
+0.0056W2-0.02F2-0.0067 WF
R2=0.62 P<0.01
n=54 d=0.87
nRMSE=22.6%
6000
5000
4000
3000
Model
establishment
2000
1000
1000 2000 3000 4000 5000 6000 7000
Measured value/(kg hm-2)
R2=0.53 P<0.01
n=19 d=0.83
nRMSE=24.4%
6000
5000
4000
3000
Model
validation
2000
1000
1:1线 1:1 line
0
0
0
0
Estimated value/(kg hm-2)
0.00587W2-0.035F2-0.00597WF
R2=0.83 P<0.01
n=23
d=0.95
nRMSE=8.3%
R2=0.83 P<0.01
n=10
d=0.95
nRMSE=8.3%
Estimated value( kg hm-2)
Y=-397.817+9.104W+26.675F-
6000
Estimated value/(kg hm-2)
Estimated value/(kg hm-2)
Results-3:Model for Northern Xinjiang
7000
7000
0
2000
4000
6000
Measured value/(kg hm-2)
8000
1000
2000
3000
4000
5000
6000
7000
Measured value/(kg hm-2)
Fig.2 Comparison of measured and estimated yield of Xinluzao cotton in northern Xinjiang
Fig.1 Comparison of measured and estimated yield of Xinluzhong cotton in southern Xinjiang
R2 is 0.83, nRMSE is 8.3%，d is 0.95，indicating that the model is reliable for
R2 is 0.53-0.62, nRMSE is below 25%，d is above 0.80，indicating that the
predicting Xinluzhong cotton yield in Southern Xinjiang.
model is reliable for predicting Xinluzao cotton yield in northern Xinjiang.
Highest yield is 6773 325 kg/hm2 when optimal fertilizer-N is 325 kg/hm2 and
Highest yield is 6773 325 kg/hm2 when optimal fertilizer-N is 359 kg/hm2,
optimal irrigation amount is 604 mm.
optimal irrigation amount is 510 mm.
Conclusions
 Cotton variety, fertilizer-N and irrigation water are three of main factors for
cotton yield.
 Water-N coupling model was built at large scale area based on cotton
varieties. The model has R2 of 0.53-0.83, nRMSE of 8.3%-24.4%, and d
Conclusions
 Assume that fertilizer-N is optimal, cotton seed yield in Southern and
northern Xinjiang 6695 and 6609 kg/hm2, respectively. The yield in 2014
reaches 69% of the potential, and the yield would be improved by 31% if
appropriate cotton variety and irrigation technique are used.
higher than 0.85, showing the reliability of model.
 According to model, the optimal irrigation amount in the northern and
southern Xinjiang is 510 and 604 mm, and the optimal fertilizer-N is 359
and 325 kg/hm2, respectively.
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Acknowledgement
Appreciation for financial project support:
1. Elite Journal of CAST (Research subject
development in Agricultural Engineering) ;
2.National Natural Science Foundation: Study
on cotton yield model based on Metaanalysis in Xinjiang (41601604)
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