Impact of Seasonal Flooding and Post-Flood Irrigation on Soil Fertility and Salinity along River Galma, Kaduna State, Nigeria

Abstract

Seasonal flooding and post-flood irrigation play important roles in modifying soil fertility and salinity in floodplain agricultural systems, yet information on their combined effects in the River Galma floodplain of Kaduna State, Nigeria, remains limited. This study assessed selected soil fertility indicators and salinity status across four categories: irrigated upland, irrigated lowland, unirrigated upland, and unirrigated lowland. Three composite samples were collected from each category at 0–30 cm depth; each composite comprised four subsamples. The 12 composite samples were analyzed for particle-size distribution, pH, organic carbon, total nitrogen, available phosphorus, electrical conductivity, exchangeable bases, and exchangeable acidity. Data were subjected to analysis of variance, and means were separated using Duncan's Multiple Range Test at P ≤ 0.05. The soils were predominantly sandy loam and slightly acidic in water (pH 5.89–6.54). Organic carbon and total nitrogen were generally low. Available phosphorus was significantly higher in the lowland categories, while exchangeable-base patterns varied among categories. Electrical conductivity measured in a 1:5 soil–water extract (EC₁:₅) ranged from 79.93 to 135.93 µS cm⁻¹ and did not differ significantly among categories, indicating no significant accumulation of soluble salts at the time of sampling. The findings show category-specific nutrient distribution. Site-specific nutrient management, organic amendments, crop-residue recycling, and periodic monitoring of soil EC and irrigation-water quality are recommended for sustainable production.