Effect of Levees on Soil Water Content, Growth and Yield of Upland Rice at Savelugu Nanton District in the Northern Region of Ghana

Abstract

Water deficit is a major constraint on upland rice production, and rainfall is the most critical and least predictable climatic factor. Both the distribution and the amount of rainfall during the cropping season are therefore key determinants of the yield of upland rice, particularly in areas with less than 2000mm of annual precipitation. To investigate the effect of levees on soil water retention and on growth and yield of upland rice cultivars, I conducted field studies in Savelugu Nanton district, Ghana, in 2009 and in Ibaraki, Japan, in 2010. In Ghana, local and improved African rice cultivars were broadcast on a farmer's field on poorly drained sandy loam. In Japan, African and Japanese upland rice cultivars were drilled in an experimental field on well drained Andosol. In both experiments, soil was mounded 20cm high and wide around plots as levees. Control plots had no levees. In Ghana, levees increased the paddy yield of local cultivars by 16% and improved cultivars by 22%. In Japan, they hardly changed soil water content or growth of the rice, probably because of the gentle rainfall and the good drainage of the Andosol. The results in Ghana indicate that farmers can reduce yield losses due to water deficit in upland rice culture by using levees, which reduce runoff and facilitate moisture infiltration in less porous soils. The levees helped maintain soil water content and thus improved the growth and yield of upland rice under heavy rain on poorly drained fields in Ghana.