Date post: | 30-Dec-2015 |
Category: |
Documents |
Upload: | kalia-houston |
View: | 14 times |
Download: | 0 times |
USE OF SEA SURFACE TEMPERATURE FOR PREDICTING
OPTIMUM PLANTING WINDOW FOR POTATO AT PENGALENGAN
Rizaldi Boer
Bogor Agricultural University
E-mail: [email protected]
Introduction• Pengalengan is the main potato
production centre – 76% of potato production of
Bandung district comes from Pengalengan, while Bandung district contributes 60 % to total production of West Java
– Significant reduction in production Pengalengan will have great influence of potato supply in the region
W e s t J a v a
P e n g a l e n g a n
B a n d u n g D i s t r i c t
0
150
300
450
600
750
1 2 3 4 5 6 7 8 9 10 11 12
Month
Pla
ntin
g A
rea
(ha)
Porekat Ceboran Wuku
• There planting season for potato called Porekat (January-April), Ceboran (May-July) and Wuku (September-December). Yield at Ceboran are mostly for seeds not for trading
• ENSO may affect potato farmers in a number of ways:– False rains that may occur early
September normally triggered farmers to start planting, while the actual onset of WS may delayed to October or November. Crop will have low yield due to poor seedling
– Farmers who delay their planting up to November due late onset of rainy season may also have low yields as the seeds produce in Porekat season will lose their viability as they were kept more than 3 months
• Thus, method for predicting optimum planting window based on sea surface temperature (ENSO indicator) prior to the planting season is required to overcome the above two problems
0
150
300
450
600
750
1 2 3 4 5 6 7 8 9 10 11 12
Month
Pla
nti
ng
Are
a (h
a)
Porekat Ceboran Wuku
Plantin
g
Onset of W
S
delay
• ENSO may affect potato farmers in a number of ways:– False rains that may occur early
September normally triggered farmers to start planting, while the actual onset of WS may delayed to October or November. Crop will have low yield due to poor seedling
– Farmers who delay their planting up to November due late onset of rainy season may also have low yields as the seeds produce in Porekat season will lose their viability as they were kept more than 3 months
• Thus, method for predicting optimum planting window based on sea surface temperature (ENSO indicator) prior to the planting season is required to overcome the above two problems
0
150
300
450
600
750
1 2 3 4 5 6 7 8 9 10 11 12
Month
Pla
nti
ng
Are
a (h
a)
Porekat Ceboran Wuku
Planting tim
e delayed
Seed harvesting
time
> 3
month
• ENSO may affect potato farmers in a number of ways:– False rains that may occur early
September normally triggered farmers to start planting, while the actual onset of WS may delayed to October or November. Crop will have low yield due to poor seedling
– Farmers who delay their planting up to November due late onset of rainy season may also have low yields as the seeds produce in Porekat season will lose their viability as they were kept more than 3 months
• Thus, method for predicting optimum planting window based on sea surface temperature (ENSO indicator) prior to the planting season is required to overcome the above two problems
0
150
300
450
600
750
1 2 3 4 5 6 7 8 9 10 11 12
Month
Pla
nti
ng
Are
a (h
a)
Porekat Ceboran Wuku
Planting tim
e delayed
Seed harvesting
time
> 3
month
Methodology1. Evaluate strength of ENSO signal1. Evaluate strength of ENSO signal
2. Crop model validation2. Crop model validation
3. Simulate yields using historical data for different planting time 3. Simulate yields using historical data for different planting time
4. Develop fitting curve for yield data against planting time4. Develop fitting curve for yield data against planting time
5. Determine planting time that give maximum yield for the curves (OPT)5. Determine planting time that give maximum yield for the curves (OPT)
6. Develop distribution of OPT to define optimum planting window (OPW)6. Develop distribution of OPT to define optimum planting window (OPW)
7. Develop equation to predict OPT from sea surface prior to the OPW7. Develop equation to predict OPT from sea surface prior to the OPW
Spatial correlation between MJJA rainfall and SST
Relationship of seasonal rainfall with SST at Pacific is consistently negative while with Indian Ocean is consistently positive,
particularly for dry season rainfall
Relationship between ARJ-O and SOI/DMIM-J
Margahayu
y = 13.45x + 11.147
R2 = 0.203
-600
-400
-200
0
200
400
600
800
-30 -20 -10 0 10 20
SOI (Mei-Juni)
Ra
infa
ll A
no
ma
ly (
Jul-
Oct
)
Margahayu
y = -205.25x + 13.862
R2 = 0.065
-600
-400
-200
0
200
400
600
800
-1 -0.5 0 0.5 1
IOD (Mei-Juni)
Ra
infa
ll A
no
ma
ly (
Jul-
Oct
)
Montaya
y = 18.958x - 1.615
R2 = 0.3496
-600
-400
-200
0
200
400
600
800
-30 -20 -10 0 10 20
SOI (Mei-Juni)
Ra
infa
ll A
no
ma
ly (
Jul-
Oct
)
Montaya
y = -191.7x + 19.241
R2 = 0.0337
-600
-400
-200
0
200
400
600
800
-0.5 0 0.5 1
IOD (Mei-Juni)
Ra
infa
ll A
no
ma
ly (
Jul-
Oct
)
DMI
DMI
Form of Relationship between ARJ-O and SOI/DMIM-J
• ARJ-O=a + bSOIM-J + c(SOI*DMI)M-J
– The R2 ranged between 22% and 56% with mean of 37% – Values of coefficients b and c are 0
• This means that if the SOI is negative (indicating El-Nino) and DMI is also negative (sea surface temperature in the region of 90°E - 110°E/ 10°S –equator, near Indonesia is higher than that of 50°E - 70°E/10°S - 10°N or IDM occurs), the (SOI*DMI) value will be positive. This means that the DMI negative will counteract the reducing effect of El-Nino on rainfall. This finding is in agreement with previous studies (Yamagata et al. 2001; Kumar et al. 1999)
Result of Validation
0
5
10
15
20
25
30
35
6/1/
2002
6/4/
2002
6/5/
2002
6/11
/200
26/
12/2
002
6/12
/200
26/
15/2
002
6/15
/200
26/
15/2
002
9/1/
2002
9/2/
2002
9/3/
2002
9/5/
2002
9/5/
2002
9/9/
2002
9/15
/200
29/
15/2
002
9/16
/200
29/
17/2
002
9/18
/200
29/
19/2
002
10/7
/200
211
/1/2
002
1/3/
2003
1/5/
2003
1/10
/200
32/
15/2
003
2/20
/200
3
Planting Time
Yie
ld (t
/ha)
ObservedSimulated
0
5
10
15
20
25
30
35
0 5 10 15 20 25 30 35
Simulated Yield (t/a)O
bser
ved
Yie
ld (t
/ha)
Line 1:1
(a) (b)
Model is able to mimic real system. This means that it can be used to study how past climate affect yield variability
Observed yield data for the validation were collected from 28 farmers planted their crop in the period of June 2002-February 2003
Yearly Yield Pattern
Ceboran without Irrigation
0
5
10
15
20
25
30
35
40
1-J
an
15
-Jan
1-P
eb
15
-Peb
1-M
ar
15
-Mar
1-A
pr
15
-Ap
r
1-M
ei
15
-Mei
1-J
un
15
-Ju
n
1-J
ul
15
-Ju
l
1-A
gt
15
-Ag
t
1-S
ep
15
-Sep
1-O
kt
15
-Ok
t
1-N
ov
15
-No
v
1-D
es
15
-Des
Planting Time
Yie
ld (
t/ha)
Determine planting date that give maximum yieldDetermine planting date that give maximum yield
Develop fitting curve using Fourier RegressionDevelop fitting curve using Fourier Regression
n
kkkt ktcktbaY
10 )]'cos(*)'sin(*[
200 fitting lines
Distribution of OPT and yield at optimum planting time for Wuku Season
Ceboran without Irrigation
0
10
20
30
40
50
60
2/29
3/15
3/30
4/14
4/29
5/14
5/29
6/13
6/28
7/13
7/28
8/12
8/27
9/11
9/26
10/1
110
/26
11/1
011
/25
12/1
012
/25
Planting Date
Fre
quen
cy
OptimumPW
Ceboran without Irrigation
0
15
30
45
60
75
10 15 20 25 30 35 40 45 50
Yield (t/ha)
Fre
quen
cy
EQUATION TO PREDICT OPT FROM SOI AND DMI
• As SOI and DMI has significant impact on rainfall variability, and rainfall variability has significant impact on yield variability, the SOI and DMI can be used to define optimum planting time (OPT)
• The form of the relationship is the same as that of rainfall– OPTW = 272 + 0.843 SOIJA - 1.57 (SOI*DMI)JA
• The equation suggests that when El-Nino occur (SOI negative) but DMI also strongly negative (Indian Dipole Mode also occur), the onset of rainy season may not delay and therefore planting early in the Wuku season should have no risk. But if DMI strongly positive, then planting early in the Wuku season (early September) is not suggested.
0
SOI
-30 –25 –20 –15 –10 –5 0 +5 +10 +15 +20 +25 +30
+1.5
+1.0
-1.0
-1.5
DM
I Julian Days
This approach can also be used to estimate expected yield of potato planted in Wuku season from July-August SOI and DMI
Estimated Potato Yield at different planting time and different SOI/DMI
Concluding Remark
• Having capability to predict optimum planting time will help potato farmers in:– Avoiding drought risk at
initial stage of crop development if onset of WS is expected to delay based on SOI/DMI May-June Information
0
150
300
450
600
750
1 2 3 4 5 6 7 8 9 10 11 12
Month
Pla
nti
ng
Are
a (h
a)
Porekat Ceboran Wuku
Plantin
g
Onset of W
S
delay
Concluding Remark
• Having capability to predict optimum planting time will help potato farmers in:– Deciding which seeds
produced at Ceboran season should be sold and kept for planting in Wuku Season
0
150
300
450
600
750
1 2 3 4 5 6 7 8 9 10 11 12
Month
Pla
nti
ng
Are
a (h
a)
Porekat Ceboran Wuku
Planting
time
Seed harvesting
time
> 3
month
The Indian Ocean, like the Pacific, has an El Niño. A warm pool in the Indian Ocean moves eastward (1 to 3) in a cycle of 3 to 7 years. The same phenomenon
occurs in the Pacific (4 to 6)
10N
10S
7050 11090
EWIOD=SSTW-SSTEIOD=SSTW-SSTE