Sustainable soil management options for integration in highly diversified and intensified cropping systems

Results of the study showed that there was serious amount of NO3 leaching in fallow plots than in plots with catch crops. In fallow plots, NO3 declined in the surface soil 45-65 days after planting, but increased in the lower layers, reaching 86 kg NO3/ha at 75-100 cm depth. In plots with catch crops, NO3-N decreased in the surface layer, but did not increase in the lower layers, which showed the ability of the catch crops to take up N from the soil beyond 100-cm depth. At 0-25 cm depth, corn reduced NO3-N by 82 percent, indigo by 73 percent, and indigo plus mungbean by 66 percent. However, at 75-100 cm depth, corn reduced NO3-N by 25 percent only, indigo by 60 percent, and indigo and mungbean combined by 47 percent. Corn was effective in reducing nitrate at shallower depths due to its larger root density, but not in deeper soil layers because of its shallow rooting system. On the other hand, indigo was effective in reducing NO3 leaching at deeper soil layers (50 cm and even beyond 100 cm depth) because of its deeper rooting system than corn. These implied that indigo could serve as an effective catch crop after the dry season when there is a higher risk of leaching due to an increase in rainfall during the wet season. The evaluation of different nitrogen management schemes revealed that for wet season rice, the urea tablet deep placement could be considered a better management scheme for increasing rice productivity. Urea tablet deep placement gave higher rice yields than that of the prilled urea spad-base management scheme, and the farmers' scheme. In terms of nitrogen use efficiency (NUE), both SB and UT/DP gave comparable performance, which was 2.5 to 4.0 times greater than that of the farmers' scheme, with NUE of less than 10 kg grain/kg N applied. However, the high price of urea tablet posed a constraint on its use. In the spad-based management scheme using prilled urea, though it showed good potential, the price of the chlorophyll meter served as a constraint on its adoption