Thesis Abstract of AGS Students

An Integrated Approach for Assessing Rice Sufficiency Level in Highland Communities of Northern Thailand

Panomsak Promburom (1997)

This study aimed to assess rice sufficiency level of a highland community where natural resource was limited but population pressure was increasing. An integrated approach involving biophysical and socio-economic methods was employed in the process of data collection and analyses.

Four villages namely Watchan, Den, Nong Jed Nuai, and Huai Bong in Watchan subwatershed, Chiang Mai province was selected for the study of rice sufficiency in Karen community which comprised of 1,495 people. Aerial photographs taken in 1954 and 1983 were used as the main source of spatial data. These aerial photographs were processed to eliminate the tilt and relief displacement by using PhotoGIS and ARC/INFO, geographic information system (GIS) packages and scanning technique. Global Positioning System (GPS) was used in the field survey to collect ground control points (GCP) to be used with a Triangulated Irregular Network (TIN) for creating orthophoto images. Mosaicking of the orthophoto images produced the undistorted photo image of the entire study area.

Land use classification from the orthophoto image indicated that the characteristics of spatial objects were different in term of thinness ratio, diversity or entropy of digital number (DN) value and mean DN value (brightness). The paddy field possessed the lower thinness and diversity values but showed the highest mean DN value comparing to other land use types. The on-screen digitizing of the orthophoto image was used to create land use coverages for 1954 and 1983. The land use map in 1994 was obtained from Landsat TM analysis in the earlier study. Spatial analysis of the three land use maps were completed by using IDRISI, a raster GIS package.

The paddy rice areas were increased through time from 74 ha in 1954 to 148 ha in 1983 and to 206 ha in 1994. The upland rice area remained constant and bush fallow was slightly changed during this period. About 700 ha of the forest area was declined between 1954 and 1994 due to the expansion paddy field, bush fallow, villages and other land use types.

The average grain yield from the crop cutting method was higher than that obtained from the formal interview. Consequently, the calculated rice supporting capacity was higher than that gathered from the formal interview which indicated 18% rice deficiency. If the average rice yield was adjusted for possible yield loss and rice consumption was also adjusted for other uses in the community, then used them for re-calculating the supporting capacity, the result suggests the near equilibrium between rice supporting capacity and population in the community.

The study also revealed the major strategies that farmers usually experienced in the past to cope with rice deficiency. These included in-site employment (87%), borrowing from rice banks (65%), sale of animals (51%), borrow from relatives and neighbors (47%), and engage in growing cash crop (43%). There were only 29% of respondents who tried to increase rice productivity by expanding rice cultivated area and applying chemical fertilizers.

Scenario analysis of rice supporting capacity of the community from 1954 to 1994 obviously showed that the farmers attempted to balance the supporting capacity of land to produce rice and population growth by expanding the paddy rice area not the slash and burn areas for cultivation of upland rice.

Further scenario analysis using rice yield at 3.0 t/ha and 3.4 t/ha obtained from selected rice lines and improved management practices reported by others in the same area illustrated the capability to extend the rice supporting capacity to meet the demand for rice of 1,973 and 2,405 people as calculated from 2.0% population growth rate by the year 2008 and 2018 respectively. Sustaining food security of this community in the future may have to depend on other activities such as growing vegetables and fruit trees as well as promoting small-scale home industry. These strategies should be considered for developing alternative plans to sustain equilibrium between human need and available resources in the highlands.

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