Rainwater conservation and management as influenced by tillage, land leveling and field bunds in rainfed lowland dry seeded rice

Results showed that cumulative rainfall of about 150 and 300 mm were found adequate by majority (75 percent) of the sample farmers for completion of dry tillage and dry seeding, respectively. Though not statistically significant, fields with higher intensity of tillage was more effective in retaining water in the field, as manifested by their reduced water deficit index (WDI) values. The land level survey of the farms showed three land slope configurations: continuous sloping regular fields, continuous sloping irregular fields; and concave fields. Land level range (R) and standard deviation (S) were lower in the fields with lower slope than those with higher field slope. With the increase in plot area, levelling precision decreased and consequently WDI increased significantly. The cumulative standing water depth (SWD), WDI and grain yields in continuous sloping regular farm were statistically similar among their plots, but not in farms without plots. The farms with plots showed better status of SWD, less WDI but similar grain yields compared to those without plots in continuous sloping irregular fields. Water status was better (less WDI) and crop yields were significantly higher in middle portion of the concave farms, indicating the benefit of more water available to the rice crop. Based on bund existence and locations, the farms were classified into four categories: periphery bunded, periphery-cross bunded, cross bunded, and unbunded. The average field slope in unbunded and periphery bunded farms was lower than that of the other two bund categories. With the increase in field slope, establishment of cross bunds was observed to be effective in retaining water in periphery-cross bunded and cross bunded farms. Periphery-cross bunded farms showed higher SWD, lower WDI and significantly higher grain yields than the periphery bunded and unbunded farms. In cross bunded fields, however, yields were higher but water status was similar to the periphery bunded and unbunded fields