Soybean–Cereal Intercropping Systems as Influenced by Nitrogen Nutrition

Abstract

Little is known how to optimize N supply of cereal components in an intercropping system that considers biological nitrogen fixation (BNF) from soybean [Glycine max (L.) Merr.]. A 2‐yr field experiment was conducted to study the compatibility of soybean–cereals intercropping as influenced by varying N levels to intercropped cereals as per recommended dose of nitrogen (RDN) for respective cereals. Soybean was grown as the main crop with 100% plant population and cereals were intercropped at 2:1 ratio in additive series (without sacrificing main crop population). While the yield of intercropped maize (Zea mays L.) significantly increased up to 100% RDN, the yield of intercropped sorghum [Sorghum bicolor (L.) Moench.] and pearl millet [Pennisetum typhoides (Burm.f.) Stapf & C.E. Hubb.] increased only up to 75 and 50% RDN, respectively. The soybean yield reduced by 33.6, 37.9 and 58.3% due to intercropping with maize, sorghum and pearl millet, respectively. The soybean equivalent yield, net return, benefit cost ratio and monetary advantage index were maximum in soybean+maize intercropping provided with 100% RDN to maize. Land equivalent ratio, relative crowding coefficient and intercropping advantage were the greatest with soybean+maize intercropping proving that there was an advantage of intercropping with maize. The aggressivity and competitive ratio were higher for pearl millet and sorghum as compared to maize indicating that pearl millet and sorghum were more competitive to soybean than maize. The study indicated the possibility to reduce N fertilizer requirement by 25 and 50% in case of sorghum and pearl millet as intercrop with soybean, respectively.