The Impact of Tillage Methods on Land Resources in the Guinea Savanna Ecological Zone, Kwara State, Nigeria

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Date

2018-05

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UNIVERSITY OF ILORIN

Abstract

Man’s relation with his natural environment is a complex one. Although, he is subject to natural controls and events, he acts as the dominant force creating major long term environmental challenges like soil degradation, water pollution among others. One of such activities of man is adopting different tillage methods in crop production. This study investigated the environmental impact of tillage methods on land resources in the guinea savanna ecological zone of Kwara State, Nigeria. The objectives were to: (i) examine the effects of tillage methods on soil quality; (ii) examine the effects of tillage methods on surface runoff; (iii) determine the impact of tillage methods on crop yield; and (iv) model the pattern and processes of pollution associated with tillage methods. The study was carried out at Unilorin Teaching and Research Farm (UTRF) and National Center for Agricultural Mechanization (NCAM), Idofian during the 2015 and 2016 maize seasons. Traditional heap (T), Notill (NT), Plough/Harrow (PH) and Plough/Harrow/Ridge (PHR) tillage were applied to surface runoff plots. Treatments were replicated thrice making 12 plots at each location. Soil samples were taken from 0-15cm and 16-30cm depths. Samples of surface runoff were collected from experimental plots. Yield parameters were measured. Soil and water physico-chemical analysis were carried out using standard laboratory procedures. Data were subjected to Analysis of variance, Least Significant Difference, Tukeyʼs test, Regression analysis at α=0.05% and Soil Water Assessment Tool (SWAT). The findings of the study were that: i. ten soil physico-chemical parameters (e.g nitrate for UTRF (0.019 and 0.012mg/kg) and NCAM (0.001 and 0.025mg/kg)) were significant for PH and PHR while six (e.g soil water for UTRF (0.001 and 0.043mg/kg) and NCAM (0.029 and 0.03)) were significant for T and NT in the topsoil and subsoil (P ˂ 0.05) in the seasons; ii. ten surface runoff physico-chemical parameters (e.g nitrate with 0.001 and 0.001 mg/l in the seasons) were significant for NT and T while seven (e.g magnesium (0.001 and 0.045 mg/l in 2015) (0.001 and 0.027mg/l in 2016) were significant on PH and PHR for UTRF and NCAM sites; iii. crop yield (kg/ha) parameters showed that PH yield > NT yield (P (0.015) ˂ 0.05) > T yield (P (0.04) ˂ 0.05) and > PHR yield (P (0.046) ˂ 0.05) for UTRF and NCAM sites in 2015 while in 2016, PH yield > T yield (P (0.026) ˂ 0.05) > PHR yield (P (0.046) ˂ 0.05) and no statistical difference between PH and NT at both locations; and iv. SWAT model showed that four of nine biophysical factors examined (sediment yield-10.54 metric tons/ha, groundwater amount-174.45GWQmm, organic nitrogen- 62.62kg/ha, and nitrogen in surface runoff -5.15kg/ha) were higher for T, while three (surface runoff amount- 374.42SURQmm, evapotranspiration-752.78ETmm and soil loss-1.05USLE_LS) were higher for PH and PHR. The study concluded that tillage methods have impact on land resources, however, PH had comparatively favorable effect on the soil environment, contribution to surface runoff and crop yield. It is therefore recommended that PH should be adopted for a sustainable environment.

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Keywords

Tillage Methods, Land Resources, Guinea Savanna Ecological Zone, Kwara State

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