Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 1 of 53
3.4 Crop growth and its modeling
3.4.1 Components of plant growth
3.4.2 Empirical models
3.4.3 Process-based models
3.4.4 Case studies
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 2 of 53
3.4.4 Case studies
(1) Impact assessment
(2) Sensitivity analysis
(3) Calibration
(4) Validation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 3 of 53
? Regionalization of climatic resources
Inner-Mongolia
? Variation of climatic resources
? Assessment of impacts of climate change
on crop yields
(1) Impact assessment
--using empirical model
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 4 of 53
Yp=E?(?Q)?f(t)?f(w)?HI
f(t)= 0
(t-3)/19
1
f(w)=p/(0.0018(25+t)2(100-f)
Regionalization of climatic resources
--Inner-Mongolia
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 5 of 53
Kt=(YL-Yt)/YL
? threshold,0.6,0.5,0.3
Kw=(Yt-Yp)/Yt,
? threshold,0.6,0.5,0.3
Regionalization of climatic resources
--Inner-Mongolia
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 6 of 53
Weather data,126 stations from 1959-1998
? Radiation
? Temperature
? Rainfall
? Humidity
? wind speed
Variation of climatic resources
--using empirical model
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 7 of 53
80 90 100 110 120 130
80 90 100 110 120 130
20
30
40
50
20
30
40
50
图 2, 1 研究区域站点分布图
表 2, 1 熟制与主要农作物
熟制 农作物 分布地区
一年一熟 春小麦或春玉米 东北及内蒙北部
一年二熟 冬小麦＋夏玉米
冬小麦＋一季稻
华北
西南
一年三熟 双季稻＋冬小麦 长江以南地区
Crop rotations
Weather stations
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 8 of 53
? Climatic potential productivity(Yp)
? Temperature affecting index (Kt)
? Water affecting index (Kw)
? EOF and CCA analysis
Variation of climatic resources
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 9 of 53
80 90 100 110 120 130
80 90 100 110 120 130
20
30
40
50
20
30
40
50
19 6 0 1 97 0 1 9 80 19 9 0
- 0,4 0
0,0 0
0,4 0
80 90 100 110 120 130
80 90 100 110 120 130
20
30
40
50
20
30
40
50
1 9 6 0 1 9 7 0 1 9 8 0 1 9 9 0
-1
0
1
EOF1 of temperature
and water affecting
indices for summer crops
表 3, 3 夏粮作物距平值各个典型场的时间系数
50 年代 60 年代 70 年代 80 年代
温度系数 （ EO F 1 ） 0.06 94 0.02 71 - 0.02 77 - 0.04 21
水分系数 （ EO F 1 ） - 0.03 - 0.10 8 0.03 03 0.08 8
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 10 of 53
80 90 100 110 120 130
80 90 100 110 120 130
20
30
40
50
20
30
40
50
1 9 6 0 1 9 7 0 1 9 8 0 1 9 9 0
- 2, 0 0
0, 0 0
2, 0 0
80 90 100 110 120 130
80 90 100 110 120 130
20
30
40
50
20
30
40
50
1 9 6 0 1 9 7 0 1 9 8 0 1 9 9 0
- 2, 0 0
0, 0 0
2, 0 0
表 3, 6 秋粮作物距平值各个典型场的时间系数
50 年代 60 年代 70 年代 80 年代
温度系数 （ EO F 1 ） 0.03 6 - 0.12 07 0.05 05 0.03 46
水分系数 （ EO F 1 ） 0.14 2 0.00 84 0.20 28 - 0.33 29
EOF1 of temperature
and water affecting
indices for fall crops
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 11 of 53
表 4, 3 气候生产潜力 E O F 展开各典型场不同年代的时间系数
50 年代 60 年代 70 年代 80 年代
夏粮作物 （ EO F 1 ） - 4 7, 3 2 - 2 2 0, 5 7 5 2 9, 7 9 - 2 2 9, 1 1
秋粮作物 （ EO F 1 ） 7 8 2, 8 6 2 4 7, 6 6 1 7 0, 9 3 - 9 8 4, 2 3
80 90 100 110 120 130
20
30
40
50
20
30
40
50
80 90 100 110 120 130
1 9 6 0 1 9 7 0 1 9 8 0 1 9 9 0
- 2 0 0 0
0
2 0 0 0
80 90 100 110 120 130
80 90 100 110 120 130
20
30
40
50
20
30
40
50
1 9 6 0 1 9 7 0 1 9 8 0 1 9 9 0
- 4 0 0 0
0
4 0 0 0
EOF1 of potential
productivity for both
summer and fall crops
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 12 of 53
表 3, 4 夏 秋 粮作物水热条件与环流因子相关分析
夏粮作物 秋粮作物
温度系数 E O F 1 水分系数 E O F 1 温度系数 E O F 1 水分系数 E O F 1
环流因子 西伯利亚高压 梅雨指数 梅雨指数 梅雨指数
相关系数 - 0, 4 7 6 - 0, 6 4 - 0, 3 6 2 0, 4 1 5
表 4, 2 我国主要分界线夏粮作物与秋粮作物的气候生产潜力 ( kg / 亩 )
优年气候 生产潜力 劣年气候 生产潜力
界线 夏粮作物 秋粮作物 夏粮作物 秋粮作物
南岭一线 1200 1200 400 400
长江一线 1000 1200 300 300
黄河－淮河一线 800 1200 200 300
长城一线 400 800 100 200
The influences of circulation factors on temperature and water indices
Maximum/minimum potential productivity from south to north
*15=kg/ha
Good year Bad year
Summer crops Fall crops
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 13 of 53
Yield data,30 provinces from 1959-
1998
? Maize
? Winter wheat
? Rice
Assessment of impacts of climate
change on crop yields
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 14 of 53
Economic data,30 provinces from 1959-1998
? Labor
? Mechanic
? Fertilizer
? Electric power
? Irrigation
Assessment of impacts of climate
change on crop yields
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 15 of 53
Y = Yt + ?Y
Y = Ye + Yc
? Y,crop yields
? Ye,economic yields,function of
labor,mechanic,fertilizer,electric power,
irrigation
? Yc,Yields from climatic impacts
Assessment of impacts of climate
change on crop yields
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 16 of 53
? Sensitive index of yield to climate,
?Yc/?Yp
? Affecting index of impacts of climate on
yields,
Yc/Ye
Assessment of impacts of climate
change on crop yields
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 17 of 53
Sensitivity Index,SI=?Y/ ?X
?Y,variation of Yc (climate yield)
?X,variation of Yp(potential productivity)
a b
图 6, 2 粮食生产气候敏感性指数分布粮食生产气候敏感性指数分布
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 18 of 53
Index of climate impact,CI=Yc/ Yt
Yc,climate yield
Yt,trend (economic) yield
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 19 of 53
Index of climate impact
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 20 of 53
? Input variables
? Parameters
(2) Sensitivity analysis for process-
based crop models
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 21 of 53
Objective
? To predict 10 years of county
maize and sorghum yields with
the ALMANAC
? To test sensitivity of yields to
solar radiation,rainfall,soil
depth,curve number,and plant
available water of the soil
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 22 of 53
Methods
? Original input data
? Scenario input data
? Relative sensitivity Index
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 23 of 53
Original Input Data
? Nine counties with mean yield of maize and
sorghum
? Weather data from nearest available weather
station
? Soil type with the largest acreage in county's
soil survey
? Soil parameters from the soil database
? Realistic values for crop parameters from
yield trials for each county
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 24 of 53
Scenario Input Data
Changed one variable at a time,
? -11% to 10% daily solar radiation
? -20% to 20% rainfall
? Soil layer depths of 1.5m,1.2m,1.0,and 0.8m
? -25% to 26% plant available water
? Highest and lowest curve numbers
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 25 of 53
Relative sensitivity equation
Relative Sensitivity = |(Y(X+?X)-
Y(X))/(?X/X)|
Where Y is the simulated result,and X is
the variable studied (Wilkerson et al.,1983)
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 26 of 53
Simulated Results
Ma iz e Sorg hum
Me an
erro r Bias RM SE
Me an
erro r Bias RM SE
% Mg ha
- 1
Mg ha
- 1
% Mg ha
- 1
Mg ha
- 1
To ta l 2.6 0.1 4 0.5 5 - 0.6 - 0.0 7 0.1 9
Irri ga ti on 3.7 0.2 7 0.4 6 - 4.6 0.2 3 0.4 0
Dryl an d 1.6 0.0 4 0.6 4 3.4 0.0 9 1.2 5
? Mean error = (simulated yield-measured
yield)/measured yield
? Bias = simulated yield - measured yield
? RMSE = root mean square error
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 27 of 53
Average Relative Sensitivity Index
for all the counties
SR R SD PAW CN
Maiz e
Tot al 0.57 1.03 0.48 0.27 4.02
Irriga tio n 0.49 0.75 0.30 0.25 1.99
Drylan d 0.65 1.32 0.66 0.30 6.05
Sorghum
Tot al 0.54 0.53 0.28 0.26 2.85
Irriga tio n 0.74 0.20 0.20 0.32 0.76
Drylan d 0.33 0.87 0.36 0.20 4.94
SR--Solar Radiation; R--Rainfall; SD--Soil Depth;
PAW--Plant Available Water; CN--Curve Number
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 28 of 53
Conclusion
? ALMANAC realistically simulated
mean yields in all counties for both
maize and sorghum
? Yields were the most sensitive to
change of curve number for both maize
and sorghum with dryland
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 29 of 53
Conclusion
? For both dryland and irrigated maize,
the order of significant variables was,
curve number,rainfall,soil depth,plant
available water,and solar radiation
? For irrigated sorghum,the rank of
significant variables was,solar
radiation,curve number,rainfall,soil
depth,and plant available water
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 30 of 53
Discussion
? Curve number is the most important of
variables for the crop modeling,How to
estimate its value accurately is worth
discussing,
? With different scenario data sets,the
coefficient variance of simulated yields
was larger than that with original data
sets,This would be interesting for future
studies,
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 31 of 53
Experiments,
? Northeastern China,soybean,spring
wheat
? Northern China,maize,winter wheat
? Changjiang Delta,rice
Calibrations for process-based
crop models
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 32 of 53
Experiment design,
? Light distribution for different densities in
canopy
? Harvest index
? LAI and related parameters
Calibrations for process-based
crop models
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 33 of 53
? Survey of crop yields
Validations for process-based
crop models
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 34 of 53
Maize and Sorghum Simulation
Under Water-Limiting Conditions
Yun Xie,James R,Kiniry,
Vernon Nedbalek
Validations for process-based
crop models
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 35 of 53
? Crop models should accurately simulate
grain yields in extreme climatic conditions
? To evaluate the ability of ALMANAC and
CERES to simulate maize and sorghum
(for ALMANAC only) grain yields under
the dry conditions at the several yield-trial
sites in central and southern Texas in 1998,
INTRODUCTION
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 36 of 53
? Average rainfall in central and southeastern
Texas
1969-1997 449 mm for March-July
1998 123 mm for March-July
? Mean maize yield was 58% of the mean for
the previous 20 years for 13 counties
? Mean sorghum yield was 87% of the 20-yr
mean for these counties
INTRODUCTION
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 37 of 53
Measured data,
? Garst Seed company measured dryland,
and irrigated maize and sorghum yields in
their yield trials at several sites in these
regions,
? These data provided an excellent set of
tests for demonstrating yield simulation
under severe drought stress,
INTRODUCTION
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 38 of 53
? Data from 17 field sites in central and
southeastern Texas
? 9 sites were solely maize sites,6 were solely
sorghum sites,and 2 had both maize and
sorghum
? 3 maize sites were irrigated,while all the
sorghum sites were dryland
? Data at each site included hybrids grown,yields,
planting and harvest date,row spacing,and
irrigation amounts
DATA SETS
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 39 of 53
? Maize hybrids Garst 8285 and Garst 8325
? Sorghum hybrids Garst 5616 and Garst
5319
? Daily maximum and minimum air
temperatures and precipitation from the
nearest weather station
? Daily solar radiation values were the
monthly averages for 20 years for the
nearest available weather station,
DATA SETS
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 40 of 53
Crop yield
survey sites
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 41 of 53
Soil data,
? Soil types determined from the soil surveys
? Soil samples collected from all 16 sites
? 47 total soil cores taken from yield trial sites
? Soil parameters derived from the
information in each soil survey,with soil
layer depths changed according to the soil
cores
DATA SETS
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 42 of 53
Soil sampling
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 43 of 53
Soil sampling
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 44 of 53
Soil samples
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 45 of 53
? Planting to maturity 1600 GDD8 for maize
and 1500 for sorghum
? HI of maize was 0.54,HI of sorghum was
0.45
? HI of maize could decrease to as low as
0.30,HI of sorghum could decrease to 0.44
because of severe drought
Crop Parameters For ALMANAC
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 46 of 53
? Models realistically simulated grain yields
? Mean error*
ALMANAC,–3.4% for sorghum,
4.4% for maize
CERES,–1.1% for maize
* [(simulated yield – measured yield) /
measured yield]
RESULTS AND DISCUSSION
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 47 of 53
Sorghum simulated with ALMANAC
0 2 4 61 3 5 7
S i m u l a t e d Y i e l d ( M g / h a )
0
2
4
6
1
3
5
7
M
e
a
s
u
r
e
d
Y
i
e
l
d
(
M
g
/
h
a
)
G a rst 56 16
G a rst 53 19
1,1 li ne
F it li ne
y = 1, 0 1 x - 0, 0 4
r
2
= 0, 8 5 n = 1 3
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 48 of 53
Maize simulations with ALMANAC
0 2 4 6 81 3 5 7 9
S i m u l a t e d Y i e l d ( M g / h a )
0
2
4
6
8
1
3
5
7
9
M
e
a
s
u
r
e
d
Y
i
e
l
d
(
M
g
/
h
a
)
G a rst 8 3 2 5
G a rst 8 2 8 5
1, 1 l i n e
F i t l i n e
y = 0, 9 3 x + 0, 1 8
r
2
= 0, 9 5 7 n = 2 0
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 49 of 53
Maize simulations with CERES
1
0 2 4 6 81 3 5 7 9
S i m u l a t e d Y i e l d ( M g / h a )
0
2
4
6
8
1
3
5
7
9
M
e
a
s
u
r
e
d
Y
i
e
l
d
(
M
g
/
h
a
)
G ar s t 8 32 5
G ar s t 8 28 5
1,1 l i ne
F i t l i ne
y = 0, 8 0 x + 0, 9 7
r
2
= 0, 8 7 8 n = 2 0
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 50 of 53
? ALMANAC and CERES realistically
simulated crop yields for individual sites
in these extreme climatic conditions
? These models could be valuable tools for
risk assessment of grain production
? The models showed promise for
applications in climates with high
probability of drought stress,
CONCLUSION
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 51 of 53
? For dryland,ALMANAC more accurate
than CERES,because LAI and kernel
weight in CERES appeared to be overly
sensitive to drought stress
? For irrigation,the models had similar
simulated yields
DISCUSSION
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 52 of 53
? Actual soil parameters from soil cores
were important for simulations of both
models
? Accuracy in future application of these
models similarly will depend on accurate
soil descriptions
DISCUSSION
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 53 of 53
Thanks
2012-3-21 Assessment of Climate/Change Impacts 1 of 53
3.4 Crop growth and its modeling
3.4.1 Components of plant growth
3.4.2 Empirical models
3.4.3 Process-based models
3.4.4 Case studies
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 2 of 53
3.4.4 Case studies
(1) Impact assessment
(2) Sensitivity analysis
(3) Calibration
(4) Validation
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 3 of 53
? Regionalization of climatic resources
Inner-Mongolia
? Variation of climatic resources
? Assessment of impacts of climate change
on crop yields
(1) Impact assessment
--using empirical model
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 4 of 53
Yp=E?(?Q)?f(t)?f(w)?HI
f(t)= 0
(t-3)/19
1
f(w)=p/(0.0018(25+t)2(100-f)
Regionalization of climatic resources
--Inner-Mongolia
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 5 of 53
Kt=(YL-Yt)/YL
? threshold,0.6,0.5,0.3
Kw=(Yt-Yp)/Yt,
? threshold,0.6,0.5,0.3
Regionalization of climatic resources
--Inner-Mongolia
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 6 of 53
Weather data,126 stations from 1959-1998
? Radiation
? Temperature
? Rainfall
? Humidity
? wind speed
Variation of climatic resources
--using empirical model
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 7 of 53
80 90 100 110 120 130
80 90 100 110 120 130
20
30
40
50
20
30
40
50
图 2, 1 研究区域站点分布图
表 2, 1 熟制与主要农作物
熟制 农作物 分布地区
一年一熟 春小麦或春玉米 东北及内蒙北部
一年二熟 冬小麦＋夏玉米
冬小麦＋一季稻
华北
西南
一年三熟 双季稻＋冬小麦 长江以南地区
Crop rotations
Weather stations
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 8 of 53
? Climatic potential productivity(Yp)
? Temperature affecting index (Kt)
? Water affecting index (Kw)
? EOF and CCA analysis
Variation of climatic resources
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 9 of 53
80 90 100 110 120 130
80 90 100 110 120 130
20
30
40
50
20
30
40
50
19 6 0 1 97 0 1 9 80 19 9 0
- 0,4 0
0,0 0
0,4 0
80 90 100 110 120 130
80 90 100 110 120 130
20
30
40
50
20
30
40
50
1 9 6 0 1 9 7 0 1 9 8 0 1 9 9 0
-1
0
1
EOF1 of temperature
and water affecting
indices for summer crops
表 3, 3 夏粮作物距平值各个典型场的时间系数
50 年代 60 年代 70 年代 80 年代
温度系数 （ EO F 1 ） 0.06 94 0.02 71 - 0.02 77 - 0.04 21
水分系数 （ EO F 1 ） - 0.03 - 0.10 8 0.03 03 0.08 8
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 10 of 53
80 90 100 110 120 130
80 90 100 110 120 130
20
30
40
50
20
30
40
50
1 9 6 0 1 9 7 0 1 9 8 0 1 9 9 0
- 2, 0 0
0, 0 0
2, 0 0
80 90 100 110 120 130
80 90 100 110 120 130
20
30
40
50
20
30
40
50
1 9 6 0 1 9 7 0 1 9 8 0 1 9 9 0
- 2, 0 0
0, 0 0
2, 0 0
表 3, 6 秋粮作物距平值各个典型场的时间系数
50 年代 60 年代 70 年代 80 年代
温度系数 （ EO F 1 ） 0.03 6 - 0.12 07 0.05 05 0.03 46
水分系数 （ EO F 1 ） 0.14 2 0.00 84 0.20 28 - 0.33 29
EOF1 of temperature
and water affecting
indices for fall crops
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 11 of 53
表 4, 3 气候生产潜力 E O F 展开各典型场不同年代的时间系数
50 年代 60 年代 70 年代 80 年代
夏粮作物 （ EO F 1 ） - 4 7, 3 2 - 2 2 0, 5 7 5 2 9, 7 9 - 2 2 9, 1 1
秋粮作物 （ EO F 1 ） 7 8 2, 8 6 2 4 7, 6 6 1 7 0, 9 3 - 9 8 4, 2 3
80 90 100 110 120 130
20
30
40
50
20
30
40
50
80 90 100 110 120 130
1 9 6 0 1 9 7 0 1 9 8 0 1 9 9 0
- 2 0 0 0
0
2 0 0 0
80 90 100 110 120 130
80 90 100 110 120 130
20
30
40
50
20
30
40
50
1 9 6 0 1 9 7 0 1 9 8 0 1 9 9 0
- 4 0 0 0
0
4 0 0 0
EOF1 of potential
productivity for both
summer and fall crops
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 12 of 53
表 3, 4 夏 秋 粮作物水热条件与环流因子相关分析
夏粮作物 秋粮作物
温度系数 E O F 1 水分系数 E O F 1 温度系数 E O F 1 水分系数 E O F 1
环流因子 西伯利亚高压 梅雨指数 梅雨指数 梅雨指数
相关系数 - 0, 4 7 6 - 0, 6 4 - 0, 3 6 2 0, 4 1 5
表 4, 2 我国主要分界线夏粮作物与秋粮作物的气候生产潜力 ( kg / 亩 )
优年气候 生产潜力 劣年气候 生产潜力
界线 夏粮作物 秋粮作物 夏粮作物 秋粮作物
南岭一线 1200 1200 400 400
长江一线 1000 1200 300 300
黄河－淮河一线 800 1200 200 300
长城一线 400 800 100 200
The influences of circulation factors on temperature and water indices
Maximum/minimum potential productivity from south to north
*15=kg/ha
Good year Bad year
Summer crops Fall crops
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 13 of 53
Yield data,30 provinces from 1959-
1998
? Maize
? Winter wheat
? Rice
Assessment of impacts of climate
change on crop yields
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 14 of 53
Economic data,30 provinces from 1959-1998
? Labor
? Mechanic
? Fertilizer
? Electric power
? Irrigation
Assessment of impacts of climate
change on crop yields
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 15 of 53
Y = Yt + ?Y
Y = Ye + Yc
? Y,crop yields
? Ye,economic yields,function of
labor,mechanic,fertilizer,electric power,
irrigation
? Yc,Yields from climatic impacts
Assessment of impacts of climate
change on crop yields
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 16 of 53
? Sensitive index of yield to climate,
?Yc/?Yp
? Affecting index of impacts of climate on
yields,
Yc/Ye
Assessment of impacts of climate
change on crop yields
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 17 of 53
Sensitivity Index,SI=?Y/ ?X
?Y,variation of Yc (climate yield)
?X,variation of Yp(potential productivity)
a b
图 6, 2 粮食生产气候敏感性指数分布粮食生产气候敏感性指数分布
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 18 of 53
Index of climate impact,CI=Yc/ Yt
Yc,climate yield
Yt,trend (economic) yield
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 19 of 53
Index of climate impact
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 20 of 53
? Input variables
? Parameters
(2) Sensitivity analysis for process-
based crop models
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 21 of 53
Objective
? To predict 10 years of county
maize and sorghum yields with
the ALMANAC
? To test sensitivity of yields to
solar radiation,rainfall,soil
depth,curve number,and plant
available water of the soil
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 22 of 53
Methods
? Original input data
? Scenario input data
? Relative sensitivity Index
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 23 of 53
Original Input Data
? Nine counties with mean yield of maize and
sorghum
? Weather data from nearest available weather
station
? Soil type with the largest acreage in county's
soil survey
? Soil parameters from the soil database
? Realistic values for crop parameters from
yield trials for each county
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 24 of 53
Scenario Input Data
Changed one variable at a time,
? -11% to 10% daily solar radiation
? -20% to 20% rainfall
? Soil layer depths of 1.5m,1.2m,1.0,and 0.8m
? -25% to 26% plant available water
? Highest and lowest curve numbers
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 25 of 53
Relative sensitivity equation
Relative Sensitivity = |(Y(X+?X)-
Y(X))/(?X/X)|
Where Y is the simulated result,and X is
the variable studied (Wilkerson et al.,1983)
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 26 of 53
Simulated Results
Ma iz e Sorg hum
Me an
erro r Bias RM SE
Me an
erro r Bias RM SE
% Mg ha
- 1
Mg ha
- 1
% Mg ha
- 1
Mg ha
- 1
To ta l 2.6 0.1 4 0.5 5 - 0.6 - 0.0 7 0.1 9
Irri ga ti on 3.7 0.2 7 0.4 6 - 4.6 0.2 3 0.4 0
Dryl an d 1.6 0.0 4 0.6 4 3.4 0.0 9 1.2 5
? Mean error = (simulated yield-measured
yield)/measured yield
? Bias = simulated yield - measured yield
? RMSE = root mean square error
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 27 of 53
Average Relative Sensitivity Index
for all the counties
SR R SD PAW CN
Maiz e
Tot al 0.57 1.03 0.48 0.27 4.02
Irriga tio n 0.49 0.75 0.30 0.25 1.99
Drylan d 0.65 1.32 0.66 0.30 6.05
Sorghum
Tot al 0.54 0.53 0.28 0.26 2.85
Irriga tio n 0.74 0.20 0.20 0.32 0.76
Drylan d 0.33 0.87 0.36 0.20 4.94
SR--Solar Radiation; R--Rainfall; SD--Soil Depth;
PAW--Plant Available Water; CN--Curve Number
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 28 of 53
Conclusion
? ALMANAC realistically simulated
mean yields in all counties for both
maize and sorghum
? Yields were the most sensitive to
change of curve number for both maize
and sorghum with dryland
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 29 of 53
Conclusion
? For both dryland and irrigated maize,
the order of significant variables was,
curve number,rainfall,soil depth,plant
available water,and solar radiation
? For irrigated sorghum,the rank of
significant variables was,solar
radiation,curve number,rainfall,soil
depth,and plant available water
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 30 of 53
Discussion
? Curve number is the most important of
variables for the crop modeling,How to
estimate its value accurately is worth
discussing,
? With different scenario data sets,the
coefficient variance of simulated yields
was larger than that with original data
sets,This would be interesting for future
studies,
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 31 of 53
Experiments,
? Northeastern China,soybean,spring
wheat
? Northern China,maize,winter wheat
? Changjiang Delta,rice
Calibrations for process-based
crop models
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 32 of 53
Experiment design,
? Light distribution for different densities in
canopy
? Harvest index
? LAI and related parameters
Calibrations for process-based
crop models
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 33 of 53
? Survey of crop yields
Validations for process-based
crop models
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 34 of 53
Maize and Sorghum Simulation
Under Water-Limiting Conditions
Yun Xie,James R,Kiniry,
Vernon Nedbalek
Validations for process-based
crop models
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 35 of 53
? Crop models should accurately simulate
grain yields in extreme climatic conditions
? To evaluate the ability of ALMANAC and
CERES to simulate maize and sorghum
(for ALMANAC only) grain yields under
the dry conditions at the several yield-trial
sites in central and southern Texas in 1998,
INTRODUCTION
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 36 of 53
? Average rainfall in central and southeastern
Texas
1969-1997 449 mm for March-July
1998 123 mm for March-July
? Mean maize yield was 58% of the mean for
the previous 20 years for 13 counties
? Mean sorghum yield was 87% of the 20-yr
mean for these counties
INTRODUCTION
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 37 of 53
Measured data,
? Garst Seed company measured dryland,
and irrigated maize and sorghum yields in
their yield trials at several sites in these
regions,
? These data provided an excellent set of
tests for demonstrating yield simulation
under severe drought stress,
INTRODUCTION
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 38 of 53
? Data from 17 field sites in central and
southeastern Texas
? 9 sites were solely maize sites,6 were solely
sorghum sites,and 2 had both maize and
sorghum
? 3 maize sites were irrigated,while all the
sorghum sites were dryland
? Data at each site included hybrids grown,yields,
planting and harvest date,row spacing,and
irrigation amounts
DATA SETS
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 39 of 53
? Maize hybrids Garst 8285 and Garst 8325
? Sorghum hybrids Garst 5616 and Garst
5319
? Daily maximum and minimum air
temperatures and precipitation from the
nearest weather station
? Daily solar radiation values were the
monthly averages for 20 years for the
nearest available weather station,
DATA SETS
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 40 of 53
Crop yield
survey sites
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 41 of 53
Soil data,
? Soil types determined from the soil surveys
? Soil samples collected from all 16 sites
? 47 total soil cores taken from yield trial sites
? Soil parameters derived from the
information in each soil survey,with soil
layer depths changed according to the soil
cores
DATA SETS
Chapter 3
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Soil sampling
Chapter 3
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Soil sampling
Chapter 3
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Soil samples
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 45 of 53
? Planting to maturity 1600 GDD8 for maize
and 1500 for sorghum
? HI of maize was 0.54,HI of sorghum was
0.45
? HI of maize could decrease to as low as
0.30,HI of sorghum could decrease to 0.44
because of severe drought
Crop Parameters For ALMANAC
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 46 of 53
? Models realistically simulated grain yields
? Mean error*
ALMANAC,–3.4% for sorghum,
4.4% for maize
CERES,–1.1% for maize
* [(simulated yield – measured yield) /
measured yield]
RESULTS AND DISCUSSION
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 47 of 53
Sorghum simulated with ALMANAC
0 2 4 61 3 5 7
S i m u l a t e d Y i e l d ( M g / h a )
0
2
4
6
1
3
5
7
M
e
a
s
u
r
e
d
Y
i
e
l
d
(
M
g
/
h
a
)
G a rst 56 16
G a rst 53 19
1,1 li ne
F it li ne
y = 1, 0 1 x - 0, 0 4
r
2
= 0, 8 5 n = 1 3
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 48 of 53
Maize simulations with ALMANAC
0 2 4 6 81 3 5 7 9
S i m u l a t e d Y i e l d ( M g / h a )
0
2
4
6
8
1
3
5
7
9
M
e
a
s
u
r
e
d
Y
i
e
l
d
(
M
g
/
h
a
)
G a rst 8 3 2 5
G a rst 8 2 8 5
1, 1 l i n e
F i t l i n e
y = 0, 9 3 x + 0, 1 8
r
2
= 0, 9 5 7 n = 2 0
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 49 of 53
Maize simulations with CERES
1
0 2 4 6 81 3 5 7 9
S i m u l a t e d Y i e l d ( M g / h a )
0
2
4
6
8
1
3
5
7
9
M
e
a
s
u
r
e
d
Y
i
e
l
d
(
M
g
/
h
a
)
G ar s t 8 32 5
G ar s t 8 28 5
1,1 l i ne
F i t l i ne
y = 0, 8 0 x + 0, 9 7
r
2
= 0, 8 7 8 n = 2 0
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 50 of 53
? ALMANAC and CERES realistically
simulated crop yields for individual sites
in these extreme climatic conditions
? These models could be valuable tools for
risk assessment of grain production
? The models showed promise for
applications in climates with high
probability of drought stress,
CONCLUSION
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 51 of 53
? For dryland,ALMANAC more accurate
than CERES,because LAI and kernel
weight in CERES appeared to be overly
sensitive to drought stress
? For irrigation,the models had similar
simulated yields
DISCUSSION
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 52 of 53
? Actual soil parameters from soil cores
were important for simulations of both
models
? Accuracy in future application of these
models similarly will depend on accurate
soil descriptions
DISCUSSION
Chapter 3
2012-3-21 Assessment of Climate/Change Impacts 53 of 53
Thanks
