Sustainability of soybean-based cropping systems on a Vertic Inceptisol: 2. Simulated yield gaps, soil water balance and soil organic carbon
2007
Singh, P | Pathak, P | Wani, S P | Srinivas, K | Jangawad, L S
Crop simulation models were used to evaluate the long-term effects of improved versus traditional management of a Vertic Inceptisol on the performance of soybean-chickpea sequential (SB-CP) and soybean/pigeonpea intercrop (SB/PP) systems. Traditional management (sowing on flat landform and no crop residues additions) and improved management (sowing on broadbed-and-furrow (BBF) landform and additions of composted crop residues and Gliricidia pruning) treatments were applied to shallow and medium-deep phases of the soil in a watershed. Yield gap between potential rainfed yield and actual yield of cropping systems increased over time. Yield gap of cropping systems with improved management was less as compared to the traditional management on the medium-deep soil; but did not differ much on the shallow soil. Simulated deep drainage of water was more in the shallow soil than medium-deep soil, which was further increased with improved management. Thus, the lack of crop yield response to improved management on the shallow soil could be attributed to greater leaching of soil carbon and other nutrients beyond the rooting zone. In spite of decreasing trends in soil organic carbon (OC) over time, simulated OC retention in the soil was higher with the additions of crop residues and with the SB/PP system as compared to the SB-CP system. Simulations also showed that crop residues additions @ 8 t ha-1 yr-1 would be required to maintain soil OC at levels observed at the beginning of study. The need for crop residue application can be less if practices such as surface application of crop residues and minimum tillage are adopted.
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