Soybean-chickpea rotation on Vertic Inceptisols. II. Long-term simulation of water balance and crop yields
Singh, P.; Alagarswamy, G.; Hoogenboom, G.; Pathak, P.; Wani, S.P.; Virmani, S.M.
Field Crops Research 63(3): 225-236
ISSN/ISBN: 0378-4290 DOI: 10.1016/s0378-4290(99)00038-6
In rainfed agriculture, climatic variability has profound effects on the performance of management systems in improvements of productivity and use of natural resources. A field study was conducted on a Vertic Inceptisol during 1995-1997 seasons at the ICRISAT Center, Patancheru, India, to study the effect of two landforms, i.e., broadbed-and-furrow (BBF) and flat, and two soil depths (shallow and medium-deep) on crop yield and water balance of a soybean-chickpea rotation. Using two seasons experimental data, a soybean-chickpea sequencing model was evaluated and used to extrapolate the results over 22 years of historical weather records. The simulation results showed that in 70% of years total runoff for BBF was greater than 35 mm (range 35-190 mm) compared to greater than 60 mm (range 60-260 mm) for flat on the shallow soil. In contrast on the medium-deep soil it was greater than 70 mm (range 70-280 mm) for BBF compared to greater than 80 mm (range 80-320 mm) for the flat landform. Thedecrease in runoff on BBF resulted in a concomitant increase in deep drainage for both soils. In 70% of years, deep drainage was greater than 60 mm (range 60-390 mm) for the shallow soil and ranged from 10 to 280 mm for the medium-deep soil. In 70% of years, the simulated soybean yields were greater than 2200 kg ha-1 (range 2200-3000 kg ha-1) and were not influenced by landform or soil depth. In the low rainfall years, yields were marginally higher for the BBF than for the flat landform, especially on the shallow soil. Stimulated chickpea yields were higher for the medium-deep soil than for the shallow soil. In most years, marginally higher chickpea yields were simulated for the BBF than for the flat landform on both soil types. In 70% of years, the chickpea yields were greater than 500 kg ha-1 (range 500-1500 kg ha-1) for the shallow soil, and greater than 800 kg ha-1 (range 800-1960 kg ha-1) for the medium-deep soil. Total productivity of soybean-chickpea rotation was greater than 3000 kg ha-1 (range 3000-4150 kg ha-1) for the shallow soil and greater than 3450 kg ha-1 (range 3450-4700 kg ha-1) for the medium-deep soil in 70% of years. These results showed that in most years BBF, landform increased rainfall infiltration into the soil and had marginal effect on yields of soybean and chickpea. Crop yields on Vertic Inceptisols can be further increased and sustained by adopting appropriate rain water management practices for exploiting surface runoff and deep drainage water as supplemental irrigation to crops in a watershed setting.