Evaluation of Soil Erosion Effects on Soil Productivity Using Productivity Index Model in Makurdi, Benue State, Nigeria

AJON A.T., AGBER P.I., ALI A.

A field experiment was conducted at the Teaching and Research Farm of the College of Agronomy, University of Agriculture, Makurdi (Latitude 7o46’ – 7o50’N and Longitude 8o36’ – 8o40’E) during the 2015 and 2016 cropping seasons. Soil erosion plots (runoff plots) were set up under a slope gradient of 2.5 % to evaluate the effects of soil erosion on soil productivity using modified productivity index (PIm) model under rainfed condition. Soil management practices namely, bare fallow (control), 4 and 8 t/ha mulched maize, maize + cowpea and unmulched maize were replicated three times. The data collected on runoff, soil loss, soil properties and grain yield of maize were analyzed using analysis of variance test based on randomized complete block design (RCBD). Correlation analysis was performed to test the relationship between PIm and erosion parameters, and grain yield of maize. The effects of erosion on soil productivity using the modified productivity index (PIm) model indicated PIm value of 0.20 under 8 t/ha mulched maize management compared to PIm values of 0.10 obtained at the start of the experiment, and 0.03 and 0.04 for bare fallow plots in 2015 and 2016 respectively. These values are low which implies that runoff and soil loss had high effects on soil productivity of the study site. There was no significant correlation between PIm and runoff, and soil loss. The relationship between PIm and grain yield of maize showed significant positive correlation (r = 0.902) in the second cropping season. Differences in soil characteristics as a result of runoff and soil loss affected soil productivity and eventually grain yield of maize.