Residual effect of organic manure on weed population and nitrogen uptake in greengram under rice-maize-greengram system

Abstract

Intensive cropping system exploits huge amount of costly inputs. Continuous intensification causes a decline in factor productivity and soil health. Apart from the integrated nutrient management, legume inclusions also mitigate the problem. But the weed dynamics in zaid (grown during March to June) legume crop like greengram are not taken care of earlier. This study emphasizes the residual impact of integrated nutrient management with Brassicaceous seed meal (BSM) and neem cake on weed population in greengram under rice-maize- greengram system. Results showed that the major weed flora in summer greengram was Echinochloa colona (L.) Link., Oplismenus composites (L.) P. Beauv., Cyperus rotundus L., Caesulia axillaris Roxb., Phyllanthus virgatus G. Forst., Alternanthera philoxeroides (Mart.) Griseb. and Physalis minima L. The minimum density of O. composites was recorded with BSM and neem cake applied plots. Integrated nutrient management significantly reduced the nitrogen uptake by weeds, hence resullted better crop growth and yield of greengram which was also higher in the treatment where BSM and neem cake was applied. Better weed control and higher greengram yield were obtained with the application of pendimethalin (750 g/ha) as pre-emergence herbicide followed by hoeing at 25 days after sowing under residual fertility of neemcake applied plots. This result emphasized the inclusion of legume crop in the intensive cropping system with residual fertility which does not require any nutrient addition for yield sustainability.