Tillage effects on growth and yield of blackgram ( Phaseolus mungo) and cowpea ( Vigna unguiculata) after wet-season rice on an alluvial sandy clay-loam in eastern India

Abstract

Dry-season ploughing was compared with no-tillage under otherwise identical cultural conditions for effects on the growth and yield of blackgram ( Phaseolus mungo) and fodder cowpea ( Vigna unguiculata). The crops were grown during winter and summer respectively after wet-season rice on an alluvial sandy clay-loam of eastern India. Prior season tillage treatments for rice, viz. puddling, dry ploughing and no-tillage, were included in the experimental design for their residual effects on the dry-season crops. At the early stages of crop growth, dry-season ploughing increased the shoot and root weight per plant, the number of secondary roots per plant, rooting depth and the nodule number per plant for both blackgram and cowpea. Ploughing increased the shoot/root ratio of blackgram in previously puddled soil whereas that of cowpea was not affected. Faster growth in ploughed soil resulted in an increase in grain yield of blackgram (21% and 40% in two seasons of study) and fodder yield of cowpea (33% and 35% in two seasons). Wet-season puddling had no adverse effects on either root growth or crop yield. Surface-soil strength measured after wetting the soil at the end of cowpea growing seasons was on an average 2.5 times greater in no-tilled than in ploughed soil but was similar in puddled and non-puddled soil. Soil water potential under blackgram was directly influenced by dry-season tillage treatments whereas under cowpea, the potential was more indirectly influenced by the differential extraction of water by the crop. It appears that increased soil strength was the major cause of reduced root growth under the no-tillage treatment. Therefore, ploughing was a superior treatment for better growth and yield of dry-season crops, irrespective of whether the soil was puddled or not for the wet-season rice.