a study of the effect of sorghum intercropping with cowpea and soybean on yield of fodder sorghum

to study the effect of strip intercropping pattern with cowpea and soybean on sorghum fodder yield an experiment was conducted at research farm of university of tehran (karaj) during 2005. the experiment was arranged in a randomized complete block design of four replications. the plant proportions included pure culture of sorghum (sss); cowpea (ccc) and soybean (ggg) each in 12 rows; vs different patterns of strip intercropping of 4 rows cowpea: 4 rows sorghum: 4 rows soybean (csg); 4 rows soybean: 4 rows sorghum: 4 rows soybean (gsg); 4 rows cowpea: 4 rows sorghum: 4 rows cowpea (csc); 4 rows soybean: 8 rows sorghum (gss) and 4 rows cowpea: 8 rows sorghum (css). the results revealed that strip intercropping patterns exerted significant effects on sorghum fodder yield, and as well, on legumes seed yield. the highest biomass yield of fodder sorghum (22079 kg/ha) was obtained from pure sorghum culture (sss) while the lowest biomass yield (10469 kg/ha) obtained from the combination of four rows of each of the three crops (csg). the highest legumes seed yield was obtained from the legumes' pure cultures (ccc or ggg). the different strip intercropping patterns significantly affected the quality of fodder sorghum (p?0.05) too. the highest fodder digestibility (71%) was obtained from strip intercropping patterns of css and gss; the highest crude protein (15.2%) from csg and finally the highest crude fiber (48.1%) from pure sorghum (sss). considering the extra sorghum biomass and the extra legumes seed yield (8-30 percent) from strip intercropping pattern of csg, and also the good quality of fodder sorghum at css, gss and csg intercropping patterns as compared to pure sorghum culture (sss), conclusion can be drawn that the intercropping of the two legume crops (cowpea and soybean) together with sorghum in a 4:4:4 row pattern is assuredly beneficial. besides, the increasing crop biodiversity and reducing crop intra-specific competition, would result in higher land equivalent ratio (ler= 1.25) for both sorghum fodder yield & quality.