Nitrogen contribution and soil improvement by legume green-manuring in rice-wheat cropping on an acid clay loam soil

abonos nitrogenados abonos verdes clay soils crop yield cropping patterns engrais vert fertilidad del suelo green manures loam soils nitrogen fertilizers oryza sativa plan de culture rendement des cultures rendimiento de cultivos soil chemicophysical properties soil fertility sol argileux sol sablolimoneux suelo arcilloso suelo franco triticum aestivum