Nutrient management for rainfed lowland rice in northeast Thailand

摘要: Average grain yields of rainfed lowland rice in northeast Thailand are the lowest region, and they barely changed past decade. Improved fertilizer management is one few options to enhance cropping system productivity but related results from previous studies were often disappointing sometimes contradictory, possibly due large variability soil water resources. Therefore, objectives this study develop a site-specific nutrient approach, propose decision tool for farmers. For purpose, we conducted on-farm experiments Kumpa-Oong Village, Roi Et Province, during 2003–2005 seasons. Tested treatments designed based on topographic field position. A comparison characteristics between lower upper fields revealed significantly higher fertility (higher pH, TOC, TSN, CEC, clay, silt content; sand content). Across seasons treatments, valley bottom (VB; 2.82 t ha � 1 ) than middle terraces (UMT; 1.68 ). In all seasons, significant treatment effects detected only UMT fields. But individual both toposequence positions showed that limited average response was mainly caused by low or even negative responses with control yield, i.e., indigenous supply. missing occurred at fields, most probably because attainable these as result Thus, recommendations need take field-specific supply into account. Based results, proposed helps farmers choose adequate their knowledge specific characteristics. On-farm testing next step show whether approach acceptable can contribute resource-use efficiency productivity.