Influence of conjuctive use of organic and inorganic source of nutrients in rice (Oryza sativa) on crop growth, yield components, yield and soil fertility in rice- sunflower (Helianthus annuus) sequence

A field experiment was carried out during 2001 and 2002 at Agricultural College Farm, Rajendranagar, Hyderabad, to study the effect of conjunctive use of nutrients in rice on rice (Oryza sativa L.)-sunflower (Helianthus annuus L.) cropping system. Rice fertilized with 75% recommended level of 120 kg Nlha and supplemented with 25% N through organic sources removed more N,P and K from the soil and gave significantly more seed yield (39.57 qlha) than by the application of N through the fertilizer alone. The yield was increased to 43.67 and 42.91 qlha by substituting 25% N through the bulky organic manure of FYM and vermicompost. The substitution of 25% N through green leaf manures, viz. Gliricidia and sunnhemp, increased the production to 41.83 and 43.90 qlha. Plant height, capitulum diarr ster, filled seedslcapitulim and seed yield of sunflower were significantly reduced by reducing the level of fertilize~s to 75 or 50 % of the recommended level of 80, 50 and 30 kglha NPK. The crop gave mean seed yield of 8.18 qlha with the recommended level of 120 kg Nlha to preceding rice through the fer- tilizer. But the residual fertility of nutrients by the application of 75% N through fertilizer and rest through FYM or vermicompost to rice significantly increased the seed yield of sunflower to 9.23 and 9.14 qlha respectively. Sub- stitution of 25% N through Gliricidia or sunnhemp to rice also significantly increased the seed yield of succeed- ing sunflower to 8.82 and 8.70 qlha. The soil-available N, P and K was also more by the conjuctive source of fer- tilizer and organic manures applied to rice in rice-sunflower cropping system compared to the initial values.