Least Limiting Water Range of Sandy Loam in South-Eastern Nigeria Under Different Tillage Methods

Abstract

In this study, the Least Limiting Water Rang (LLWR) of a sandy loam soil under different tillage practices (conventional tillage, conservative tillage and no tillage) and soil depths (0-25cm, 25-50cm, 50-75cm and 75-100cm) were determined using moisture contents at field capacity, permanent wilting point, aeration and mechanical resistance. The upper limit of the LLWR for the three tillage treatments at different soil depths were determined at field capacity rather than air filled porosity, while the lower limit was determined at permanent wilting point rather than penetration resistance. On the average, for conventional tillage, conservative tillage and no tillage, least limiting water ranges of 0.066cm3/cm3, 0.056cm3/cm3 and 0.052cm3cm3were obtained. The least limiting water values indicate that LLWR increased as tillage intensity increased. Bulk density was also determined for the tillage practices at different depths, for conservative tillage, the lowest value of bulk density was at 75-100cm depth (1.53g/cm3) while the highest value was obtained at 0-25 and 25-50cm depth (1.55g/cm3). For conventional tillage, the lowest value was obtained at 75-100cm depth (1.43g/cm3) and highest at 0-25cm depth (1.47g/cm3). No tillage was also lowest at 75-100cm depth (1.53g/cm3) and highest at 0-25cm depth (1.59g/cm3). On the average, bulk densities of 1.56g/cm3, 1.54g/cm3 and 1.45g/cm3 were recorded for no tillage, conservative tillage and conventional tillage respectively, this shows that bulk density decreases with intensive tillage. Also correlation coefficient for bulk density and least limiting water range at different tillage methods and soil depths gave an R2>0.9 for all the tillage methods. Test of significance also gave p-values of 0.03, 0.05 and 0.03 for conventional tillage, conservative tillage and no tillage respectively.