Evaluation of jatropha (Jatropha curcas) and castor (Ricinus communis) cake as a source of nutrient and soil amendment in spring sunflower (Helianthus annuus)-maize (Zea mays) sequence

A fixed plot field experiment was conducted during 2007 and 2008 at New Delhi to find out the effect of de­ oiled seed cake of jatropha (Jatropha curcas L.) and castor (Ricinus communis L.) as a source of nutrient alone I and in various combination with inorganic sources in spring sunflower (Helianthus annuus L.)-maize (Zea mays L.) sequence. Nine combinations of three organic sources viz. jatropha cake (JC), castor cake (CC) and FYM @ 100%, 50% and 25% recommended dose of nitrogen (RDN) and three inorganic levels viz. 0%, 50% and 75% recommended dose of fertilizer (RDF) were tested in sunflower along with RDF through inorganic (80, 26.2 and 30 kg N, P and K/ha) and control. Residual effects of treatments were evaluated on the succeeding maize along with RDF to fallow-maize (120, 26.2 and 33.3 kg N, P and K/ha). In first year of experiment, RDF to sunflower pro­duced significantly the highest seed yield (2.64 t/ha) over other fertility levels barring the treatment of 75% RDF + 25% RDN either through JC (2.61 t/ha) or CC (2.52 t/ha). In the next season, 50% RDF + 50% RDN through JC (3.43 t/ha) being on par with 50% RDF + 50% RDN either through CC (3.36 t/ha) or FYM (3.22 t/ha) produced marked increase in seed yield over remaining fertility combinations. Grain yield of succeeding maize due to re­sidual effect of 50% RDF + 50% RDN through JC (2.72 and 2.89 t/ha in respective year) was significantly higher than other residual fertility treatments, followed by 50% RDF + 50% RDN through CC (2.45 and 2.62 t/ha) in both the years. The highest system productivity in terms of sunflower seed equivalent (3.52, 4.75 t/ha) and net returns (Rs 45,418, 69,407/ha) were recorded with the application of 50% RDF + 50% RDN through JC, followed by 50% RDF + 50% RDN through CC during both the years. Nutrient uptake followed trend similar to yield. Com­pared to control and RDF, pH and bulk density decreased with increase in the quantity of organics and reverse trend was recorded with respect to organic carbon content.