Spatial Variability of Soil Properties and Implications for Climate-Smart Rice Production in four Agricultural Zones in Anambra State, Nigeria

Abstract

Spatial variability in soil properties strongly influences water dynamics, nutrient availability, and crop productivity in tropical agroecosystems, thereby affecting the sustainability of climate-smart rice production systems. This study evaluated the spatial variability of selected soil physical, hydraulic, and chemical properties across four agro-ecological zones (Awka, Anambra, Aguata, and Onitsha) of Anambra State, southeastern Nigeria. Surface soil samples (0–30 cm) were collected from georeferenced locations differing in elevation and landscape characteristics. Laboratory analyses were conducted to determine particle size distribution, bulk density (BD), saturated hydraulic conductivity (Ksat), soil pH, and organic matter (OM). Descriptive statistics, analysis of variance (ANOVA), correlation analysis, and principal component analysis (PCA) were employed to evaluate variability and relationships among soil properties. Results revealed considerable spatial heterogeneity across the study area. Sand content ranged from 332 to 582 g kg⁻¹, while clay content varied between 218 and 354 g kg⁻¹. Bulk density ranged from 1.346 to 1.458 g cm⁻³, whereas Ksat varied from 0.0182 to 0.0468 cm hr⁻¹. Soil pH was moderately acidic (5.3–5.7), while OM content ranged from 2.2 to 3.3%. ANOVA indicated no significant zonal differences in Ksat and BD, suggesting that micro-scale variability exerted a stronger influence than agro-ecological classification. PCA explained 96.5% of total variability, with soil texture and hydraulic properties constituting the dominant controlling factors. The findings highlight the importance of site-specific soil and water management strategies for improving rice productivity, enhancing water-use efficiency, and strengthening climate resilience in southeastern Nigeria.