Physical Land Suitability Evaluation for Irrigated Maize and Potatoes in Zimbabwe

Abstract

Land evaluation is the key to sustainable agriculture. The aim of the study was to use soil survey data to assess the suitability of land for irrigated maize and potatoes. The study was based on a detailed soil survey, at scale of 1:12500, performed at the Karimba Estate in eastern Zimbabwe. On the basis of soil morphological, analytical, and terrain characteristics, land units were demarcated and a land unit map produced. Land qualities necessary to assess crop performance were selected following FAO guidelines. Crop requirements were matched with the land qualities, and suitability of land for the crop was then assessed. The diagnostic factors of each land quality were assigned a factor rating. Overall physical suitability of a land unit for a land utilization type (LUT) was computed from individual factor ratings. Rooting conditions (R) and topography (T) were land qualities identified to limit the yield of maize and potatoes. Rooting conditions, as determined by effective depth (Rd) and surface stones (Rs), were found to be the most important limiting factors to crop production in the study area. A suitability model based on depth, stoniness, and topography was developed; overall suitability = Rd × Rs × T. Results showed that 51% of the area is highly suitable (S1) or moderately suitable (S2) for maize production, and 49% is unsuitable (N). About 44% of the area is highly suitable to moderately suitable for potato production, while nearly 56% of the area is not suitable.