Effects of Intercropping Cowpeas with Maize and Phosphorous Levels on Growth and Yields of Cowpeas in Meru County, Kenya
Cowpea (Vigna unguiculata L. Walp) is a legume that is grown for various uses Humans consume it as grain or leaf vegetable and as fodder by livestock. It has 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 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 results show that with mean plant heights of 41.56 cm, 42.43 cm, 43.00 cm and 45.03 cm respectively for 0, 25, 50 and 75 kg/ha of SSP, plant height at maturity were significantly affected by both fertilizer levels and cropping system (p<0.05). The number of pods and cowpeas grain yields were significantly also significantly affected (p<0.05). Sole cowpeas recorded the tallest plants, highest number of pods. The mean grain yields for 0, 25, 50 and 75 kg/ha of SSP were 400 kg, 496.88 kg, 593 kg and 699.88 kg respectively with 75 kg/ha. All the Land Equivalent Ratios for intercropping system were greater than one (LER>1) thus showing that intercropping was beneficial. Intercropping cowpeas and maize at 75 kg/ha phosphorous gave the highest Land Equivalent Ratio. It is recommended that in a cowpeas-maize intercropping system application of 75 kg/ha should be adopted. More work should be done to determine effects of intercropping cowpeas with cereal crops other than maize.
Keywords: Maize, cowpeas, intercropping, Tigania.