Pedological Survey and Suitability Ratings of Kighir Farms at Makurdi, for Swamp Rice (Oryza Sativa) Production

Abstract

A thorough soil survey was conducted on selected soils in Kighir, Makurdi Local Government Area, Benue State, Nigeria, with the goal of characterizing, classifying, and rating the soils for better management and agricultural sustainability of rainfed rice production. The study locations cover around 1500000 m² (150 hectares) of land. Kighir is located at 7º33'45'' N and 8º55'42'' E. The study used a stratified random sample technique based on physiographic unit. Slope and flood plain landforms were analyzed, and three soil units were established.  On the field, three pits were dug and their morphologies reported. All three soil units had depths between 113 and 150 cm. Unit I had well-drained soil, Unit II had fairly poorly-drained soil, and Unit III had poorly-drained soil. In unit I, the soils were sandy clay loam to sandy loam; in unit II, the soils were sandy clay loam to clay; and in unit III, the soils were sandy clay loam over all horizons. The research area's soils have a good structure (strong, moderate, subangular, blocky). Strong to moderately acidic soil reactions were observed (pH 5.2-6.0). The organic carbon content of the soils is moderate to low (1.00-1.10%) in the surface horizons and moderate to high (1.40-1.25%) in the subsurface horizons. At the surface horizons, total nitrogen levels ranged from (0.02 - 0.21%). Calcium was the most abundant element in the soils, with values ranging from (1.05 - 2.36 cmol/kg) at the surface horizons to (2.41 -3.36 cmol/kg) in the subsurface horizons. The available phosphorus in the surface horizons was rather high (4.05 -4.36 mg/kg), but substantially lower (1.54 - 1.62 mg/kg) in the subsurface horizons.  The soils' percentage base saturation ranged from 62 to 86%. According to USDA soil taxonomy and WRB, soils of unit I were classified as Aernic Paleustalfs /Aeric Lixisols, soils of unit II were classified as Aeric Endoaqualfs /Endogleyic Gleysols, and soils of unit III were classified as Ustic Epiaquerts /Epiclayic Vertisols. The soil properties were compared to the land requirements for rice cultivation. Soils in unit I (poor water area) were rated marginally appropriate (S3), soils in unit II were rated most suitable (S1), and soils in unit III were rated moderately suitable (S2).