Seedbed Types and Integrated Nutrient Management Options for Cowpea Production in the Southern Rangelands of Semi-arid Eastern Kenya

Abstract

The southern rangelands of Kenya are difficult environments prone to frequent droughts. The effect of the flat (farmer practice), tied-ridging and contour furrows water harvesting technologies (seedbed types) and five integrated nutrient management practices on the performance of rainfed cowpeas was studied on-farm at the southern rangelands of Kenya during the 2006 short rains season. Cowpea grain yield responded positively under manure at 10 t ha^–1 irrespective of the water harvesting technology (seedbed) type. There was a negative effect on cowpea grain yields on addition of inorganic fertilizers probably due to the high water-holding property and capacity of manure. The highest cowpea grain yield was recorded in the treatments without inorganic fertilizers. Inorganic fertilizers tend to absorb water from their surroundings as opposed to manure that tend to hold water and release it to the surrounding plants. Tied-ridged seedbed type gave higher cowpea yield than contour furrows and flat seedbeds irrespective of the soil fertility option applied. Cowpea plots under the tied-ridging and contour furrows water harvesting technologies (seedbed types) applied together with manure at 10 t ha^–1 produced significantly higher yields than those under the farmers practice. As such, if farmers are willing to apply manure at 10 t ha^–1, it is upon them to make a choice between the two seedbed types depending on the economic implications of their preparation. Keeping of small ruminants and poultry is one of the main economic activities in this area and as such, limited amounts of manure are readily available and affordable. In the absence of any soil fertility application option, the tied-ridging water harvesting technology should be recommended to farmers in the southern rangelands of Kenya.