Direct and residual effects of fertilizers and biofertilizers on yield, nutrient uptake and economics of groundnut (Arachis hypogaea)–rice (Oryza sativa) cropping system

A two-year field experiment was conducted during the winter (rabi) and rainy (kharif) seasons of 2010–12 at Deodhe, Ratnagiri (Maharashtra), to study the direct and residual effects of different doses of fertilizers and biofertilizers on yield, nutrient uptake and economics of groundnut (Arachis hypogaea L.)–rice (Oryza sativa L.) cropping system. Increasing dose of fertilizers up to 125% recommended dose of fertilizers (RDF) significantly increased pod yield by 79.7% and haulm yield by 63.3% of groundnut over the control. Uptake of N, P and K by groundnut also improved significantly with successive increase in doses of fertilizers up to 125% RDF. Succeeding rice showed significant response to residual fertilizer levels up to 100% RDF in grain yield and up to 125% in straw yield and registered 16.9 and 25.4% increase over the control, respectively. The N, P and K uptake by succeeding rice and total NPK uptake, rice-grain equivalent yield, production efficiency, net returns and benefit: cost ratio in groundnut–rice cropping system also improved significantly with increase in doses of fertilizers up to 125% RDF applied to groundnut. The crop inoculated with biofertilizers (Rhizobium+phosphate-solubilizing bacteria) recorded significantly higher pod (1.74 t/ha) and haulm yields (3.64 t/ha) of groundnut and grain (5.34 t/ha) and straw yields (5.52 t/ha) of succeeding rice over the control. Inoculation of groundnut with biofertilizers significantly increased N, P, K uptake by groundnut and succeeding rice (except N uptake by rice straw) as well as total N, P and K uptake (393.1 kg/ha), rice–grain equivalent yield (9.92 t/ha), net returns (66.8×10³ /ha) and benefit: cost ratio (2.01) in groundnut–rice cropping system over no inoculation. This treatment also recorded the maximum production efficiency of the system (38.8 kg/ha/day). Rice crop responded significantly to each higher level of fertilizer up to 125% RDF (direct) in terms of grain and straw yields as well as N, P and K uptake. Application of 125% RDF to rice recorded significantly higher total N, P and K uptake (447.1 kg/ha), rice–grain equivalent yield (10.89 t/ha), production efficiency (42.6 kg/ha/day), net returns (78.3×10³/ha) and benefit: cost ratio (2.17) in groundnut–rice cropping system.