Effect of chemical fertilizers on yield and nutritive value of intercropped Sudan grass (Sorghum Sudanense) and cowpea (Vigna unguiculata L. Walp) forages grown in an adverse environment of western Saudi Arabia

A field experiment was carried out during 2009/10 and 2010/11 seasons at Hada Al-Sham experimental Farm of King A/Aziz University in Jeddah, Saudi Arabia. The objective was to evaluate the effect of some chemical fertilizers on productivity and nutritive value of Sorghum Sudanense Var. Panar intercropped with Cowpea (Vigna unguiculata L. Walp) in an adverse condition of soil and irrigation water. The chemical fertilizers applied were 50 kg/ha of urea (46% N), 50 kg/ha of triple superphosphate (46% P), 50 kg/ha of KNO3, 50 kg/ha of NPK (20:20:40) and a control for check. Sudan grass and Cowpea were sown as sole crops and as a mixture. Treatments were laid out in a split plot design with the fertilizer treatments in the main plots and the intercropping treatments in the subplots. Parameters measured were plant height and nutritive value for the Sudan grass, fresh and dry yields and the land equivalent ratio (LER). The chemical fertilizers had no significant (P <= 0.05) effect on productivity but significantly improved forage quality. Intercropping of Sudan grass and Cowpea significantly (P <= 0.05) increased forage productivity and improved forage quality and land equivalent ratio (LER). Cowpea was not a good competitor as it disappeared following the first cut in the first season.