EFFECTS OF TILLAGE METHODS AND SOIL DEPTHS ON SOIL CHEMICAL PROPERTIES IN SOUTH EASTERN NIGERIA

Abstract

Mechanical movement in agricultural land affects soil properties, thereby leading to poor yield. In this study, selected soil chemical properties were assessed under different tillage methods and soil depths at the experimental farm site of the Department of Agricultural and Bioresources Engineering, Nnamdi Azikiwe University, Awka, Southeastern Nigeria. Three tillage practices were involved in this study; conventional tillage- by properly tilling the soil with plough and harrow, conservative tillage- tilling with one tractor pass, and no tillage- without tilling the soil. The soil chemical properties tested were; pH, soil nitrogen, soil potassium, soil phosphorous, soil electrical conductivity and soil organic carbon content. Soil samples were collected from each of the tillage methods at different soil depths; 0-25cm, 25-50cm 50-75cm and 75-100cm soil depths and tested in the laboratory for these soil chemical properties. The effects of tillage methods and soil depths on soil chemical properties were determined using statistical analysis of variance (ANOVA).From the pH result, a mean pH of 7.02, 6.08 and 6.51 were obtained for conservative tillage, conventional tillage and no tillage respectively, for electrical conductivity, a mean electrical conductivity of 52.1μs/cm, 52.9μs/cm and 54.4μs/cm were obtained for conservative tillage, conventional tillage and no tillage respectively. For soil potassium, means of 7.6ppm, 7.79ppm, and 7.82ppm were obtained for conservative tillage, conventional tillage and no tillage respectively. Result of soil organic carbon gave average of 6.8g/kg, 6.4g/kg and 6.8g/kg for conservative tillage, conventional tillage and no tillage respectively, while for soil nitrogen, mean of 1.5g/kg, 1.25g/kg and 1.67 g/kg were obtained for conservative tillage, conventional tillage and no tillage respectively. Result of soil phosphorous gave averages of 5.46mg/kg, 4.77mg/kg and 4.81mg/kg for conservative tillage, no tillage and conventional tillage respectively. The ANOVA result shows that only soil electrical conductivity and soil nitrogen were significant at p≤0.05 level.