Statistical analysis of a long-term experiment on rice (Oryza sativa)-based cropping systems

The data of a long-term experiment on nutrient management in cropping systems conducted under the Project Directorate for Cropping Systems Research, Modipuram, for Navasari (Gujarat) (1987-98) and Rajendranagar (Andhra Pradesh) (1988-98) centres were analysed to evaluate the effect of fertilizers in combination with organic manures on the productivity of cereal-based crop sequences and also to examine whether the yields exhibited trend over the years. The experiment included 12 treatments of fertilizers in combination with organic manure in randomized complete-block design. The analysis revealed that the maximum yield (3.486 tonnes/ha of rice and 2.154 tonnes/ha of wheat) of rice (Oryza sativa L.)-wheat (Triticum aestivum L.emend. Fiori & Paul.) sequence at the Navasari centre was realized when 100% of the recommended NPK dose (100, 50, 0 kg/ha of N, P2O5, K2O for rice and 120, 60, 0 kg/ha of N, P2O5 K2O for wheat) was applied to both the crops through fertilizers. However, 50% recommended NPK dose through fertilizers when supplemented with 50% N equivalent through green-manure in rice, followed,by 106% recommended NPK dose through fertilizers in wheat proved a better practice from the long-term sustainability of crop yields. Further, 50% recommended NPK dose (60, 30, 30 kg/ha of N, P2O5 K2O) through fertilizers with 50% N equivalent through green-manure in rainy season rice, followed by 100%recommended NPK dose (120,60, 60 kg/ha of N, P2O5, K2O) through, fertilizers in winter rice was the most appropriate fertilization practice for obtaining the highest yield (4.926 tonnes/ha of rainy-season rice and 4.192 tonnes/ha of winter rice) of the rice-rice crop sequence at the. Rajendranagar centre.