Effect of organic and inorganic sources of nutrients on rice (Oryza sativa) – wheat (Triticum aestivum) cropping system

A field experiment was conducted during 2002–03 to 2004–05 at Malan, Himachal Pradesh, to explore the possibility of an alternative to farmyard manure (FYM) as a component of integrated nutrient management in rice (Oryza sativa L.) – wheat (Triticum aestivum L. emend. Fiori & Paol.) system. Five organic sources, viz. FYM 5 t/ha gobhi sarson straw 5 t/ha, mushroom spent compost 2.5 t/ha, FYM 2.5 t/ha + gobhi sarson straw 2.5 t/ha, FYM 2.5 t/ha + mushroom spent compost 1.25 t/ha, were applied in all possible combinations at three fertility levels, viz. 50, 100 and 150% of recommended fertilizer dose (RDF) to rice crop. Direct and residual effects of organic sources significantly affected the productivity of rice-wheat cropping system. Statistically equal rice and wheat yields were obtained with application of FYM 5 t/ha (5.03 t/ha rice, 2.48 t/ha wheat) and FYM 2.5 t/ha + mushroom spent compost 1.25 t/ha (4.94 t/ha, 2.33 t/ha), whereas gobhi sarson straw 5 t/ha recorded lower yields (4.24 t/ha, 1.99 t/ha). Rice responded significantly up to 100% recommended dose (4.77 t/ha); residual effects of fertility levels on wheat did not differ significantly. Standard control (100% RDF to both crops) resulted in significantly higher grain yield of wheat compared with mean of others receiving only 50% RDF. Nutrient uptake uptake (159.1 kg N, 35.0 kg P and 147.9 kg K/ha) and net returns (Rs 41,535/ha) from the rice-wheat cropping system recorded higher values with FYM 5 t/ha, followed by FYM 2.5 t/ha + mushroom spent compost 1.25 t/ha (155.0 kg N, 32.5 kg P and 139.0 kg K/ha; Rs 39,132/ha). The soil-available NPK status remained fairly constant under different treatments. Thus, FYM 2.5 t/ha + mushroom spent compost 1.25 t/ha applied to rice helped in sustained productivity and profitability of the cropping system statistically equal to that with FYM 5 t/ha.