Field Prediction and Potential Monitoring of Cassava Production
in Nakhon Ratchasima
A. Eiumnoh1, R. P. Shrestha1, S. Baimoung2, P. Kesawapitak3 and A. Noomhorm1
1SERD, Asian Institute of Technology, G.P.O. Box 2754, Bangkok 10501
2 Department of Meteorology, Bangkok 10260
3Department of Agriculture, Bangkok 10900
Fax:9821:650377
Abstract
The potential monitoring of cassava production in Nakhon Ratchasima province, Thailand was conducted using Remote Sensing (RS) and Geographic Information Systems (GIS) in integration. The soil units, topography and general landforms were digitized and grouped according to their surface texture, slope and elevation and types of land form respectively. The cassava productivity factors including soil moisture, drainage condition, effective soil depth, texture, organic matter content, base saturation, cation exchange capacity, .mineral reserve and fertility level were evaluated for land suitability classification. The soil, topography, landform and cassava productivity were analyzed for potential land productivity grouping. Landsat TM of 1995 was used to classify cassava area and to compare misclassified land uses with land use map of 1993. Land suitability evaluation for cassava was carried out to compare with existing cassava area. The NOAA-A VHRR data in 1993 and 1995 were used for monitoring purposes. It was found out that, however, remote sensing data are still having many limitations and .constraints in monitoring of cassava production, integration of GIS and remote sensing can be exploited to have its fullest , usefulness.
1.0 Introduction
There have been about 24 folds increase in the area of cassava cultivation in Thailand in the last three decades (Figure 1 ) to be Thailand as the major cassava producer in the region. This tremendous growth can be attributed to the unique capability r-. of cassava for producing high biological and economic yield under marginal and low-input conditions and its flexible : agronomic requirements. North-eastern region which is comparatively depressed than other regions of the country contributes .about 60 percent of the total cassava production.
Figure I. Cassava cultivation area, production and yield.
(Source: O.A.E. Agricultural Statistics, 1954/55 to 1993/94).
The popularity of cassava cultivation is attained due to both marginal land quality of North-east region and also high price fetching of cassava products in the. past. Majority of cassava produced in the country .is exported. to EEC corntries and less than 10 percent of It IS used for domestIc consumption. In the read Just ment of EEC's polIcy to restrict cassava Imports, as per 1980's agreement between Thailand and EEC, Thailand would limit the export to 5 million tons of pellets equivalent to 12 million tons of fresh roots (Titapiwatanakun, 1984). On the contrary, with the development of new high yielding varieties and expansion of cultivated area, the production trend remained increasing and is estimated to reach 17.57 million tons in the year 1996 ( TTDI, 1995).
As the production is export oriented such limitations of the trade treaty would mean that excess of production has to be consumed within the country for which it has to be seriously reconsidered either opening domestic market consumption or limit
the cassava production. In the lack of this, the country and its farmers will have to face face the challenge of a great economics loss .
Monitoring of cassava production in Thailand have been traditionally relied on field information gathering . application of advance remote sensing and GIS has not gained popularity yet in this field. Moreover, cassava can be harvested for a'longer period of time, its monitoring for production predictions becomes difficult. To cope these situations a study of three years ~ " duration has been started by Asian Institute of Technology to predict the cassava cultivation and production and suggest the suitable land for cassava cultivation. This paper, as part of the study, discusses the piece of work predicting the cassavaproduction and suggest the land suitability for cassava in Nakhon Ratchasima.
2.0 The Study Area
Nakhon Ratchasima province is situated on Korat plateau of the North-east region of Thailand covering 12,811,162 rai (O.A.E., 1992). The climate is tropical Savannah with minimum and maximum temperature ranging from 14.1 to 39.5° C. The area receives an annual rainfall of 1,062.4 mm in an average annual rainy days of 104. Paddy is the principal crop on lowland and cassava on the upland followed by sugarcane and corn. This province is the largest among the cassava producer provinces in the country
3.0 Methodology
The research methodology is presented in Figure 2 which employs the tools, such as, Remote Sensing, Geographic Information Systems (GIS) and field surveys. The basic source materials used were:
Figure 2. Conceptual framework of research methodology.
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Topo map (1:250,000), Royal Thai Survey Department, 1984 I
- Land use map (1:250,000) O.A.E., 1993
- Landsat TM hardcopy (1:250,000), February 1995.
- Soil Map (I :500,000), Soil Survey Division, 1982.
- Climate data -Published and unpublished reports, documents, etc.
The soil units, topography and general landforms were digitized from different base maps to create the thematic coverages in vector based GIS ( ARC/INFO). Landsat TM was visually interpreted for recent land use types. Existing database was used to predict the cassava yield. The cassava productivity factors including soil, moisture, drainage, effective soil depth ..texture, organic matter, base saturation, cation exchange capacity, mineral reserve and fertility level were evaluated for land suitability classification employing limitation concept combined with parametric approach. Land use requirements were ~ considered as given by LDD, 1992.
