SOIL MORPHOLOGICAL AND PHYSICAL PROPERTIES AS DETERMINANTS OF RICE PRODUCTION IN OGBOMOSO, SOUTHWESTERN NIGERIA

Abstract

Rice production in Ogbomoso, Southwestern Nigeria, depends largely on soil characteristics, which influence water retention, nutrient availability, and overall crop productivity. However, variability in soil properties across different farms may limit rice yield. This study was conducted to assess the morphological, physical, and chemical properties of soils used for rice production in selected farms in Ogbomoso. Six representative farms which are Oyebode S. and Oyebode A. (Surulere LGA), Mumuni L. and Oderinde (Ogo-Oluwa LGA), and Ogunniyi J. and Ajuwon A. (Oriire LGA) were selected for the study. Profile pits (1.5 m × 1.5 m × 2.0 m) were dug in each farm, and soil samples were collected from identified horizons. Field description of morphological properties was carried out, while laboratory analyses were conducted using standard procedures. Particle size distribution was determined using the hydrometer method, and soil chemical properties includes pH, organic carbon, total nitrogen, avail. phosphorus, exchangeable bases, and cation exchange capacity (CEC) were analyzed. Suitability evaluation was conducted using the FAO land evaluation framework. The results showed that soil pH ranged from 4.95 to 6.10, indicating moderately acidic to slightly acidic conditions. Organic carbon ranged from 1.30 to 4.31 g/kg, while total nitrogen ranged from 0.14 to 0.47 %, indicating low nitrogen content. Available phosphorus ranged from 0.16 to 3.50 mg/kg, showing severe deficiency of available phosphorus in most of the study sites. Exchangeable calcium ranged from 2.09 to 19.20 cmol/kg, magnesium from 0.46 to 1.82 cmol/kg, potassium from 0.19 to 0.78 cmol/kg, and sodium from 0.15 to 0.47 cmol/kg. CEC ranged from 3.63 to 22.32 cmol/kg, indicating low to moderate nutrient retention capacity. Soil texture varied widely, with sand ranging from 37.2% to 90.6%, silt from 1.4% to 25.4%, and clay from 6.0% to 61.4%, resulting in textural classes such as sand, loamy sand, sandy loam, sandy clay loam, and clay. Micronutrients showed Fe ranging from 72 to 241 mg/kg, Mn from 56 to 156 mg/kg, Cu from 1.11 to 1.91 mg/kg, and Zn from 1.58 to 2.58 mg/kg. Suitability evaluation revealed that climatic and topographic factors were highly suitable (S1), while soil-related limitations resulted in Mumuni L., Oyebode S. and Ajuwon A. Farm being moderately suitable (S2), Oyebode A. and Ogunniyi J. were marginally suitable (S3), while Oderinde Farm was rated not suitable (N2). In conclusion, despite favorable climatic and topographic conditions for rice production in the study areas, soil fertility constraints such as low organic matter, low nitrogen, deficiency in available phosphorus, coarse soil texture, and low CEC limit the soil productivity. Therefore, improving soil fertility through organic matter incorporation, balanced fertilizer application, and proper water management practices is essential for enhancing rice production and ensuring sustainable agricultural development in these areas.