Organic manures for increased productivity and sustained supply of micronutrients Zn and Cu in a rice-wheat cropping system

Field experiments for 3 years were carried out to assess the efficacy of organic manures (Sesbania aculeata, Leucaena leucocephala), cowpea (Vigna unguiculata) and mungbean (Vigna radiata) green manures, wheat straw and FYM (Farm Yard Manure) in enhancing the productivity of rice-wheat cropping system and for their capacity to supply Zn and CU. Green manuring with Sesbania gave the highest rice yield, whereas lowest yields were recorded with wheat straw incorporation. The organic manures had significant residual effect on succeeding wheat and the highest yields were recorded with FYM. The percent increase over no organic manure (control) in total rice-wheat productivity was the highest with Sesbania green manuring (19.5%) and lowest with wheat straw (4%). The concentration and uptake of Zn and Cu by individual crops and system was significantly greater with organic manures. The micronutrient status of soil after 3,cycles of rice-wheat cropping system declined over initial values but the decline was the least with FYM followed by green manures. Application of organic manures is desirable for sustained supply of Zn and Cu to rice-wheat cropping system soils.