Forage production potential and economics of maize (Zea mays) with legumes intercropping under various row proportions

A field experiment was conducted during the summer season of 2006 and 2007 at Sabour, Bihar to assess the production potential and economic viability of intercropping of forage maize (Zea mays L.) with cowpea [Vigna unguiculata (L.) Walp.], rice bean [Vigna umbellata (Thumb) ohwi and ohashi] and clusterbean [Cyamposis tetragonaloba (L.) Taub.] under four row proportions, viz. 1 :1, 1 :2, 2:l and 2:2. lntercropping of maize and cowpea in the row proportion 2: 2 recorded significantly higher total green fodder (43.2 Vha), dry matter (9.6 t/ha) and crude-protein yield (1.1 Vha) as well as net returns (Rs 16,104/ha) and benefit : cost ratio (1.84) compared with the other treatments except maize + rice bean planted in the ratio 2:2. The association of maize and cowpea in row ra- tio 2:2 also showed the highest land-equivalent ratio (1.84) and relative crowding coefficient (7.08), followed by maize + rice bean in 2:2 ratio. Among the component crops, maize was more competitive and aggressive than le- gume intercrops. However, maize intercropped with cowpea and rice bean both in row proportion 2:l was found to be a compatible intercropping system with lower values of aggressivity (0.01) and competition ratio (1.03). Thus in- tercropping of forage maize with cowpea or rice bean both in 2:2 row ratio are the biologically and economically sustainable intercropping systems.