Performance of rice (Oryza sativa)-based cropping systems in coastal Karnataka

A field experiment involving 6 rice (Oryza-sativa L.)-based cropping systems was conducted at Mangalore from 1988 to 1993, wherein the green-manure and residues of the grain legumes were incorporated. The grain yield of rainy-season (kharif) rice increased from 4.7 to 5.4 tonnes/ha in rice-groundnut (Arachis hypogaea L.)-cowpea [Vigna unguiculata (L.) Walp.] system as compared to a decline from 4.5 to 4.1 t/ha in rice-rice system after 5 years. The total productivity and economic returns were substantially higher in rice-groundnut-cowpea and rice-groundnut-finger millet [Eleusine coracana (L.) Gaertn.] systems compared with rice-rice systems. Significant increase in organic carbon and available K2O was observed in cropping systems where grain legumes or green-manure was incorporated.