10.3.2 The Case of Rice Production in Thailand
10.3.2.1 Current Rice Production in Thailand
From 1990 to 2010, Thailand’s (5–20
N, 98–105
E, 0–330 m.a.s.l.) rice production systems occupied in average 10.2 million ha of land across all regions of the
country (AFSIS 2012). The soil types in these areas are predominantly sandy loam,
according to the US Soil Taxonomy particle-size distribution limits, and the climate
in the area during the study period was characterized by an average annual rainfall
of 1,200 mm, distributed mostly in the period May to October. The average
maximum temperature during this period was 33.2 C and the average minimum
air temperature was 20
C. In general, the growing season rainfall for rice begins in
August and ends in November or early December. The national average rice yield
ranges between 2.0 and 2.6 Mg ha
À1 , with provinces in the northeast and the
southern regions producing lower than average and provinces in the central region
producing higher than average yields.
10.3.2.2 Testing the Model with Historical Rice Production Data
To test the impacts of the IPCC A2 and B2 climate scenarios (IPCC SRES 2000) on
rice production activities in Thailand, CropDSS was used to simulate rice yields
under three production systems, using one planting date: August 12th, for main
season rice and 25 day-old seedlings. The rice variety used in the model was the
non-photoperiod sensitive RD7 variety (Department of Agriculture, Thailand). One
application of urea chemical fertilizer at a rate of 62.5 kg ha
À1 was added on the
transplanting date and partial irrigation was applied during the early growth stages.
A one-to-one line analysis of the simulated rice yields under the rain-fed/no
nitrogen applications scenario, using recorded yields for the whole Kingdom of
Thailand as provided by the Office of Agricultural Economics and averaged for the
period 1980–1989, was applied. The model over-estimated average rice yields for
the period by 20 %, with a D-statistic of À0.78 and a Root Mean Squared Error
(RMSE) of 0.808 Mg ha
À1 , mostly in the northeast region.
10.3.2.3 Evaluating Adaptive Strategies for Rice Production
Adaptive rice production strategies under the A2 and B2 scenarios for the
2012–2019 period were evaluated using CropDSS. Under the rain-fed production
systems used in Thailand, adding 0.060 Mg of urea fertilizer and 2 Mg ha
À1 of green
manure crop residues raised rice yields by 36% and 15% respectively, as compared
to average yields during the 1980–1989 baseline years (Jintrawet and Chinvanno
2011) (Fig. 10.9). However, one needs to consider the fact that in practice, adding
urea fertilizer may promote the release of N 2 O greenhouse gas into the atmosphere,
10 Integrated Modeling of Agricultural Systems in Mountainous Areas
387
10.3.2.1 Current Rice Production in Thailand
From 1990 to 2010, Thailand’s (5–20
N, 98–105
E, 0–330 m.a.s.l.) rice production systems occupied in average 10.2 million ha of land across all regions of the
country (AFSIS 2012). The soil types in these areas are predominantly sandy loam,
according to the US Soil Taxonomy particle-size distribution limits, and the climate
in the area during the study period was characterized by an average annual rainfall
of 1,200 mm, distributed mostly in the period May to October. The average
maximum temperature during this period was 33.2 C and the average minimum
air temperature was 20
C. In general, the growing season rainfall for rice begins in
August and ends in November or early December. The national average rice yield
ranges between 2.0 and 2.6 Mg ha
À1 , with provinces in the northeast and the
southern regions producing lower than average and provinces in the central region
producing higher than average yields.
10.3.2.2 Testing the Model with Historical Rice Production Data
To test the impacts of the IPCC A2 and B2 climate scenarios (IPCC SRES 2000) on
rice production activities in Thailand, CropDSS was used to simulate rice yields
under three production systems, using one planting date: August 12th, for main
season rice and 25 day-old seedlings. The rice variety used in the model was the
non-photoperiod sensitive RD7 variety (Department of Agriculture, Thailand). One
application of urea chemical fertilizer at a rate of 62.5 kg ha
À1 was added on the
transplanting date and partial irrigation was applied during the early growth stages.
A one-to-one line analysis of the simulated rice yields under the rain-fed/no
nitrogen applications scenario, using recorded yields for the whole Kingdom of
Thailand as provided by the Office of Agricultural Economics and averaged for the
period 1980–1989, was applied. The model over-estimated average rice yields for
the period by 20 %, with a D-statistic of À0.78 and a Root Mean Squared Error
(RMSE) of 0.808 Mg ha
À1 , mostly in the northeast region.
10.3.2.3 Evaluating Adaptive Strategies for Rice Production
Adaptive rice production strategies under the A2 and B2 scenarios for the
2012–2019 period were evaluated using CropDSS. Under the rain-fed production
systems used in Thailand, adding 0.060 Mg of urea fertilizer and 2 Mg ha
À1 of green
manure crop residues raised rice yields by 36% and 15% respectively, as compared
to average yields during the 1980–1989 baseline years (Jintrawet and Chinvanno
2011) (Fig. 10.9). However, one needs to consider the fact that in practice, adding
urea fertilizer may promote the release of N 2 O greenhouse gas into the atmosphere,
10 Integrated Modeling of Agricultural Systems in Mountainous Areas
387