Effects of Intercropping Cowpeas with Maize and Phosphorous Levels on Growth and Yields of Cowpeas in Meru County

Abstract

Cowpea (Vigna unguiculata L. Walp) is a legume that is grown for various uses. It is consumed as grain, leaf for humans and as fodder by livestock with high nutritive value and high palatability. It is widely produced in sub-Saharan Africa as a source of income. It is drought tolerant and can suitably be used as an intercrop in an intercropping system. The attendant low yield of cowpea among smallholder farmers due to declining soil fertility has increased the need for site specific fertilizer recommendation. Land fragmentation and reduced arable land makes intercropping of cereals and legumes inevitable. A field experiment was conducted at Kianjai ward in Tigania West Sub County of Meru County during the March –May rain season of 2015 to investigate the effects of intercropping cowpeas with maize and four different levels of phosphorous on growth and yields of cowpeas. The treatments were sole cowpeas, sole maize, sole cowpeas planted with (0 kg/ha, 25 kg/ha, 50 kg/ha and 75 kg/ha SSP) and cowpeas intercropped with maize at (0 kg/ha, 25 kg/ha, 50 kg/ha and 75 kg /ha SSP).The design of the experiment was a Randomized Complete Block Design (RCBD) with four replicates. The experiment was monitored from March to July. The results show that plant heights at harvesting stage were significantly affected by both fertilizer levels and cropping system (p<0.05). The mean plant heights for 0 kg/ha, 25 kg/ha, 50 kg/ha and 75 kg/ha were 41.56 cm, 42.43 cm, 43.00 cm and 45.03 cm respectively. The number of branches were not significantly affected (p>0.05). The number of grains per pod were not significantly affected by cropping system (p>0.05) but were significantly affected by fertilizer level (p<0.05). The number of pods, grain weight and yields were significantly affected (p<0.05). Sole cowpeas recorded the highest number of pods, grain weight and yields. The mean grain yields for 0 kg/ha, 25 kg/ha, 50 kg/ha and 75 kg/ha were 400 kg, 496.88 kg, 593 kg and 699.88 kg respectively. The Land Equivalent Ratio was greater than one (LER>1) thus intercropping was beneficial. Intercropping cowpeas and maize at 75 kg/ha phosphorous gave the highest Land Equivalent Ratio (1.9305). It is hereby recommended that in a cowpeas-maize intercropping system application of 75 kg/ha should be adopted. More work to be done to determine effects of intercropping cowpeas with other cereal crops other than maize.