Spatial variability of soil properties under different landuse in Koupendri catchment, Benin

Abstract

The spatial distribution of soil properties especially saturated hydraulic conductivity (Ksat), Bulk density (BD), soil organic carbon (SOC), total nitrogen (TN) and available phosphorus (Avail.P) is fundamental to sustainable management of soil resources. About 291 surface soil (0-20 cm) samples were collected across three land use types (maize-sorghum (MS), rice field and fallow shrub-grassland (FSG) in Koupendri, north-west Benin using a grid sampling of 25 m x 25 m supplemented with samplings at 5 m x 5 m. Data obtained were subjected to classical and spatial statistics, Pearson’s correlation and analysis of variance using GENSTAT. The soil properties showed normal and non-normal distribution, variation was high (75-126.7 %) for Ksat, moderate (29-45 %) for SOC, C/N and Avail.P, and low (7-15) for BD and TN across the land use. Land use had significant (P < 0.05) effect on all the soil properties evaluated except C/N. The highest values of Ksat (151.6 cm/d), SOC (1.26 %), BD (1.79 g/cm<sup>3</sup>), TN (0.105 %), Avail.P (4.66 ppm) and C/N (12.14) were obtained under the MS cropland whereas porosity was highest (43.7 %) in the rice field. High significant correlation (P < 0.01) was observed among the soil properties irrespective of land use. The correlation length (65-300 m) and nugget effect ratio indicates high variation and strong spatially dependent soil properties. However, TN, BD, Avail.P and C/N were weakly spatially dependent. The variograms were fitted with mostly exponential and spherical models. The interpolation map could help in delineating different management zones and for making good agronomic decisions.