The effect of planting pattern and nitrogen fertilizer on yield of basil (Ocimum basiilicum L.) and cowpea intercropping in competition with weeds(Vigna unguiculata L.)

To investigate the effects of intercropping of basil (Ocimum basiilicum L.) and cowpea (Vigna unguiculata L.),
different levels of nitrogen fertilizers on basil and cowpea yield, an experiment was carried out during 2010 and 2011. Experimental factor were included weed treatment (weeding and unweeding), three levels of nitrogen fertilizer (0, 50 and 100 kg ha-1), different planting ratio, (P1: sole cropping of cowpea, P2: 100% cowpea+ 25% basil, P3: 100% cowpea+ 50 % basil, P4: 100% cowpea+ 25% basil, P5: sole cropping of basil). Results showed that the maximum yield of basil (430.37 kg ha-1) and cowpea (685.16 kg ha-1) recorded in 100 and 50 mixture with using of 100 and 50 kg ha-1 nitrogen fertilizer in weed control condition, respectively. In unweeding conditions, however, the maximum yield of basil (138.95 kg ha-1) was obtained in both 100 and 25 planting ratio plus 100 kg ha-1 nitrogen fertilizer. Also the highest intercropping advantage (LA= 1.74) belonged to 100 and 25 planting ratio along with 100 kg ha-1 nitrogen fertilizer and weeding. Land equivalent ratio (LER=1.43) in 100 and 50 mixture with 50 kg ha-1 nitrogen fertilizer and weeding was more than sole cropping. Also the highest relative value total (RVT= 1.88) was observed in 100 and 50 planting ratio plus 100 kg ha-1 nitrogen with weeding condition. In conclusion, cultivation of cowpea as a cover crop in basil/cowpea intercropping system could and improve nitrogen status and suppressed weed population and biomass as compared to basil sole cropping.