Incorporation of Biochar and Legumes into the Summer Gap: Improving Productivity of Cereal-Based Cropping Systems in Pakistan

Abstract

Biochar can improve soil quality, increase crop production and sequester C in agricultural systems; however, this now needs critical evaluation in a sustainable agricultural context. In Pakistan, there is a gap in cereal-based wheat–maize–wheat cropping systems that lasts between 70–80 days. This “summer gap” can be used for growing short duration legume crops, which can provide valuable grain, fodder, or green manure and can provide a sustainable input of N into agricultural systems. We have used a field-based study to determine the effect of biochar application to an alkaline, nutrient poor, soil on the productivity of legume crops grown during the summer gap. Overall, biochar application (50 t ha⁻¹) increased the productivity and yield of cowpea, mungbean and Sesbania over two cropping seasons compared to unamended non-biochar controls. The integration of biochar and legumes could be a useful strategy for improving the overall farm productivity of cereal-based cropping systems in Pakistan, by delivering a sustainable input of N to soil and providing increased yields from this additional summer gap crop.

KEYWORDS:

• biological nitrogen fixation
• farm productivity
• legume-cereal rotation
• nitrogen
• soil fertility
• sustainable nutrient cycling