The Extrapolation of Nitrogen Mangement Technology for direct-Seeded Rice in Ubon Ratchathani Province Using Geographic Information System as a Tool

Abstract

Geographic Information System (GIS) was used as a tool to evaluate land suitability in Ubon Ratchathani province for direct-seeded rice and N management technology extrapolation during 1998-2000. Six factors namely annual rainfall, soil texture, cationexchangeable capacity, climatic drought occurrence, farmers's practices and maximum depth of inundationwere attributed. The results showed that there were three categories of land suitabiligy in Ubon Ratchathani province as moderately suitable (S2), marginally suitable (S3), and not suitable (N) category. The marginally suitable areas with limitation like flooding (S3f) wee included in the S3 category. Nitrogen management for direct seeded rice -a new technology generated in the Ubon Ratchathani Rice Research Center that is 9.6 kg N/rai applied in three splits, smaller quantity of N, e.g. 1 in 4 of the total amount applied at 15 and 30 days after emergence (DAE), the remaining half applied at 45 DAE were validated and compared with farmers' practices through on-farm trials. The extrapolation and recommendation were also made on the qualities of land suitability classification basis. Onfarm trials consistently gave higher grain yield as a result of the new N management technology application as compared to farmers' practices in S2 and S3 category. Comparable grain yield of the two N applications was obtained form N category, indicating differences in environmental factors in the domains.