Influence of slope aspect and position on soil physical quality and management implications at University of Uyo Teaching and Research Farm, Akwa Ibom State, Nigeria

The effect of north and south aspects (NA and SA) and positions viz upper (US), middle (MS) and lower (LS) on soil physical quality from 2000 to 2020 was evaluated at the University of Uyo Teaching & Research Farm, to identify management factors at the Farm. Results showed that coarse sand increased while clay content decreased significantly (p < 0.05) and soil textural class was loamy sand on slope aspects and positions. Soil bulk density and total porosity were similar on the slope aspects and positions. Saturated hydraulic conductivity was significantly (p < 0.05) higher on SA (10.6 cm h–1) than NA (3.1 cm h–1) but declined by 93.03% and 52.47%, respectively in 20 years. Soil organic carbon, water-stable aggregates, mean-weight diameter of soil aggregates and structural index decreased by 14.81% and 38.33%, 60.53% and 55.53%, 31.26% and 21.71%, and 48.60% and 69.0%, respectively in NA and SA within the 20-year period. One minute infiltration rate was similar on NA and SA, while final infiltration rate, cumulative infiltration, sorptivity and transmissivity were significantly (p < 0.05) different; these soil hydraulic properties decreased in NA and SA by 83.0% and 86.43%, 52.63% and 14.29%, 81.53% and 63.9%, 95.0% and 85.63% and 90.42% and 96.11%, respectively on the aspects after the 20 years. Slope aspects and positions were generally similar in their effects on soil physical quality attributes, most of which were degraded after the 20 years. Principal component analysis (PCA) identified seven soil quality management factors namely (1) water intake, (2) soil texture, (3) soil pore space, (4) and (6) Fe and Al oxide, and (5) and (7) soil structural stability factors that could be used to improve and conserve the soil and water for increases in crop production on the farm.