Influence of Selected Ecological Farming Practices on Soil Moisture Retention and Yield of Sorghum (Sorghum bicolor (L.) Moench) and Cassava (Manihot esculanta Crantz) in Semi-Arid Yatta Sub-County, Kenya

摘要

In this study, the influence of ecological farming practices on soil moisture and yield of cassava ( Manihot esculanta Crantz) and sorghum ( Sorghum bicolor (L.) Moench) was investigated. The study was conducted in semi-arid Katangi and Ikombe divisions of Yatta sub-county between October 2010 and August 2012. A randomised complete block design with a split plot arrangement was used. Main plots were three cropping systems: (i) Intercropping; (Dolichos [ Lablab purpureus ]/Cassava, Dolichos/Sorghum, Pigeon pea [ Cajanus cajan (L.) Millsp.]/Sorghum, Pigeon pea/Cassava); (ii) Rotation; Dolichos-Cassava, Dolichos-Sorghum, Pigeon pea-Cassava, Pigeon pea-Sorghum and (iii) Monocrop (pure cassava and sorghum). Split plots were organic inputs; farm yard manure (FYM), compost and absolute control. Sorghum/pigeon pea intercrop+FYM treatment had high moisture levels during short rain season (SRS) of 2010 at Katangi (5.21%), SRS of 2011 at Ikombe (5.19%) and long rain season (LRS) of 2011 at both sites (5.83%, 12.30%). Grain yields were highest under sorghum/dolichos intercrop+ FYM during LRS of 2011 at Katangi (1.36 t ha -1 ) and Ikombe (1.48 t ha -1 ), and SRS of 2010 at Katangi (1.39 t ha -1 ) only. Cassava/dolichos intercrop recorded high soil moisture levels in both sites under sorghum/dolichos intercrop during SRS of 2010 (6.48%, 8.35%), LRS of 2011 (7.63%, 8.77%) and LRS of 2012 (6.41%, 3.65%) for Katangi and Ikombe, respectively. Tuber yields were higher under cassava/pigeon intercrop in Katangi (18.63 t ha -1 ) and Ikombe (28.73 t ha -1 ) during SRS of 2010 and LRS of 2011, and SRS of 2011 and LRS of 2012 at Katangi (20.86 t ha -1 ). Intercropping sorghum with dolichos and cassava with pigeon pea + FYM would be a viable strategy to boost crop yields in smallholder farming systems of Yatta sub-county.