Yield gap analysis of soybean, groundnut, pigeonpea and chickpea in India using simulation modeling

In India, cultivation of legumes forms an integral part of the rainfed production systems; however, their productivity over the years has remained low and unstable. Soybean and groundnut are the major oilseed crops and pigeonpea and chickpea are the major pulse crops of the country. In the present study, we have: a) characterized the distribution of these legumes in different production zones, agro-ecological zones (AEZs) and states of India; b) estimated the rainfed (water-limited) potential, achievable and current levels of farmers’ yields; c) quantified yield gaps between farmers’ yields and rainfed potential yields; and d) suggested possible ways to abridge the yield gaps. Using CROPGRO and APSIM (for pigeonpea) suite of crop models and historical weather data, rainfed potential yields and water balance of the four legumes were estimated for selected locations representing different production zones in India. The simulated rainfed potential yields were supplemented with the research station yield data of rainfed trials of the All India Coordinated Research Projects (AICRP) for respective crops. Achievable yields of the crops for the locations were taken from the Front Line Demonstrations conducted on-farm with improved technology. District average yields were consideredas the farmers’ yields. Based on these data, the yield gaps between potential and achievable yields (YG I), between achievable and farmers’ yields (YG II) and total yield gaps between potential and farmers’ yields were estimated. The farmers’ average yield of crops is 1040 kg ha-1 for soybean, 1150 kg ha-1 for groundnut, 690 kg ha-1for pigeonpea and 800 kg ha-1 for chickpea in India. Large spatial and temporal variability was observed in the yield gaps of the four legumes across the production zones. Total yield gap for the production zones ranged from 850 to 1320 kg ha-1 for soybean, 1180 to 2010 kg ha-1 for groundnut, 550 to 770 kg ha-1 for pigeonpea and 610 to 1150 kg ha-1 for chickpea. YG II formed a significant part of the total yield gap of the four legumes, indicating the need to scale-up the improved crop production technologies from on-farm demonstration sites to farmers in the production zones. Total yield gaps of legumes for the AEZs and states of India were in the similar range as for the production zones. Simulated rainfed potential yields and total yield gaps across different locations for the four legumes showed a positive and significant curvilinear relationship with crop season rainfall. Estimated surface runoff constituted11 to 54% of total rainfall received during g