Evaluation of castor (Ricinus communis) genotypes for productivity, economics, litter fall and changes in soil properties under different levels of inter-row spacing and nitrogen

A fixed plot field experiment was conducted during the rainy (kharif) seasons of 2002 and 2003 at New Delhi, to find out the effect of 3 inter-row spacings (60, 75 and 90 cm) and 3 levels of N (0, 60 and 120 kg N/ha) on performance of 2 genotypes (‘DCH 177’ and ‘DCS 9’) of castor (Ricinus communis L.) and physico-chemical properties of soil. The mean performance indicated significant superiority of ‘DCH 177’ to ‘DCS 9’ in terms of yield attributes, seed yield (27.7 and 23.9 q/ha), harvest index (9.59 and 8.92%) and net return (Rs 24,072 and 20,656/ha). The optimum N dose was worked out to be 121.6 and 100.9 kg N/ha for ‘DCH 177’ and ‘DCS 9’ respectively. Castor genotypes responded to inter-row spacing significantly. The maximum seed yield (26.5 q/ha), harvest index (9.72%) and net return (Rs 23,420/ha) were recorded with 90 cm inter-row spacing. Low temperature during December to February induced considerable fruits drop. The treatments under test also caused perceptible variation in fruits drop. Mean litter fall of 9 to 10 tonnes/ha per season was recorded. Litter fall exhibited marked increase due to decrease in inter-row spacing and increase in N levels. At the end of 2 years experimentation on the same site, physico-chemical properties like bulk density and pH recorded perceptible decrease from initial values, while soil organic carbon content and available N exhibited marked improvement over initial values.