Development of effective management plan for critical subwatersheds using SWAT model

The present investigation is an effort to develop an effective management plan for the identified critical subwatersheds of Nagwan watershed located in the eastern part of India using a precalibrated and validated Soil and Water Assessment Tool (SWAT) model. In all 60 combinations of various management treatments including crops (rice, maize, peanut and soybean), tillage (zero, conservation, field cultivator, mould board plough and conventional practices) and levels of fertilizer (existing, half of recommended and recommended) have been studied. This study revealed that crops like maize, peanut and soybean could not replace rice since they resulted in higher sediment yield compared to rice. The tillage practice with mould board plough has been found to have a more appreciable impact on the sediment and nutrient losses than conventional tillage practices for the existing level of fertilizer. Sediment yield decreased in case of zero tillage, conservation tillage and field cultivator compared to conventional tillage. On the other hand, nutrient losses increased in case of zero and conservation tillage for all levels of fertilizer compared to the other tillage treatments. In conclusion it can be stated that the sediment yield is highest in case of mould board plough followed by conventional tillage field cultivator, conservation tillage and least in zero tillage practices, whereas the nutrient losses were found to be just in the reverse order with tillage practices, indicating highest nutrient losses in mould board plough tillage practices. In view of the sediment yield and nutrient losses, the conventional tillage practice was considered to be the best as the sediment yield is less than the average soil loss and nutrient loss is within the permissible limit. Copyright (C) 2005 John Wiley Sons, Ltd.