Assessment of Salinity and Sodicity Status of Sokoto-Rima Flood Plains of Sokoto State, Nigeria and Its Implications for Agricultural Activities

Salinity and sodicity are major problems in irrigated lands, rendering them unsuitable for crop production. This study was conducted to assess the status of salinity and sodicity in the Sokoto-Rima Flood Plains of Sokoto State, Nigeria, and its implications for agricultural activities in the area. Two locations were selected for the study (Kolkolawa and Nasarawa floodplain). Soil samples were collected from surface soils at a depth of 0 – 30 cm from the two locations. The soil samples obtained were analyzed for physical and chemical properties using standard procedures. The results showed that the soils were imperfectly to poorly drained. Soil texture was loam-sand in Kolkolawa and silt clay-loam in Nasarawa. Mean soil pH values were rated slightly alkaline to strongly alkaline in Kolkolawa and moderately acidic to strongly alkaline in Nasarawa (7.2 – 7.9); organic carbon was low to medium (5.3 – 9.7 g/kg), while cation exchange capacity was medium to high (8.7 – 19.7 cmol/kg), and base saturation (70 - 71 %) was high in both locations. Electrical conductivity (0.35 – 0.79 dS/m) and sodium absorption ratio (0.13 – 0.64) were low, while exchangeable sodium percentage (ESP) (6.7 – 8.9 %) was moderate in both Kolkolawa and Nasarawa. Among the two locations, soils in Nasarawa were observed to be tending toward sodicity due to high pH (> 8.5), high sodium (1.60 cmol/kg), and ESP (8.9 %) content, which could be attributed to poor drainage, parent material, and the use of low-quality water for irrigation. Soils with high pH reduce the availability of essential nutrients like iron, zinc, manganese, and phosphorus, which are essential for plant growth. The study therefore recommends the construction of drainage systems, leaching of soil with quality water, planting of tolerant crops, and the use of farmyard manure to increase soil quality and fertility.