Abstract
The effects of integrated nutrient supply through organic manures and inorganic and bio- fertilizers were studied on soil fertility status as well as, yield and quality of sweet orange (Citrus sinensis Osbeck) grown on Vertisol under the hot sub-humid, tropical climate of central India. Combined application of these three nutrient sources proved to be far superior to their sole application. Application of farmyard manure (FYM) (to supply 50% N) and green manuring with sunhemp plus a 50% dose of NPK supplied through inorganic fertilizers showed supremacy with benefit: cost ratios of 4.59 and 6.46 respectively. While, substantial improvement in fruit quality can be achieved with the sole application of organic manures, especially FYM, all organic manurial treatments especially FYM (to meet 100% N), were highly effective in improving the physical properties and organic carbon of the soil. Considerable improvement in infiltration characteristics were observed with the application of wheat straw. Combined application of various organic manures (to supply 50% N) along with 50% NPK recorded significant increase in available N, P and K in the soil. Considerable increase in available Zn and Mn were observed with FYM, and Fe with vermicompost either as a sole application or in combinations with inorganic fertilizers. Most of the fertility parameters showed significant positive correlations with fruit yield while quality parameters showed better correlation with available K, P, Mn and Zn contents in the soil.