MJSTEM

Abstract

This study quantified soil organic carbon (SOC) stocks and soil properties across agricultural lands of Niger State, Nigeria, and assessing their implications for land capability and crop suitability. Composite samples were collected from six representative agricultural lands of Gidan Kwano (GK) Campus farm land, Federal University of Technology, Minna and Umaru Sanda Ahmadu College of Education (COE) farm land, Minna, three composite soil samples at three depth intervals (0–20, 20–40, 40–60 cm) and analyzed using standard laboratory procedures for SOC, soil pH, total nitrogen (N), cation exchange capacity (CEC), and particle size distribution. Land capability was classified using the USDA land capability system, while the suitability of maize, soybean, and millet was assessed following FAO land evaluation guidelines. SOC concentrations ranged from 7.38 to 13.97 g kg⁻¹, with consistently higher values in surface layers and marked declines with depth, reflecting reduced organic inputs and increasing bulk density. Soil pH values ranges from 5.31–6.79 indicated slightly acidic to near neutral soil conditions that are generally favorable for arable crops. Total N was low to moderate (0.35–0.70 g kg⁻¹). Cation exchange capacity (CEC) values ranged from (5.40–9.34 cmol kg⁻¹) indicated predominantly coarse textured soils with limited inherent nutrient retention capacity. Land capability assessment showed that more than half of the agricultural land is constrained by low SOC, nutrient depletion, erosion risk, and structural limitations. Crop suitability analysis identified cowpea, groundnut, soybean, cassava as the most adaptable across capability classes, maize suitability as strongly linked to SOC levels and soil structure, and millet as moderately suitable but restricted mainly by texture and water holding capacity.

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