Abstract:
The decline in soil quality is increasingly seen as a form of soil degradation and is often related to land use and soil/crop management practices. The research was conducted at the Research and Experimental Farm of the Institute for Agricultural Research (IAR) Samaru, Zaria with the aim of evaluating the influence of Jatropha curcas L. (JCL) plantation and varied management practices under JCL on soil physical quality. To achieve this aim the research was divided into two trials. The first trial involved five adjacent land uses: Arable Land (AL), Fallow Land (FL), One Year JCL plantation (OYJ), Two Years JCL plantation (TYJ) and Three Years JCL plantation (RYJ). The second trial comprised of three JCL spacing rates (1.5 m x 1.0 m, 1.5 m x 2.0 m and 1.5 m x 3.0 m) and four nitrogen levels (0 kg/ha, 60 kg/ha, 120 kg/ha and 180 kg/ha). Soil samples were collected at four depths (0-5 cm, 5-10 cm, 10-15 cm and 15-20 cm) from the various treatments under study and subjected to field and laboratory investigations for soil physical quality indicators such as infiltration, organic carbon, bulk density, aggregate stability, moisture retention, S-index etc. Result revealed that most of the parameters were significantly affected by land use. Cultivation of JCL averagely increased total nitrogen, infiltration, dry large macroaggregates (>2 mm), dry macro-aggregates (2-0.25 mm), dry mean weight diameter (MWD) and dry geometric mean diameter (GMD) by 47%, 26.1%, 28.3%, 13.4%, 18.8% and 12.2% respectively relative to land under continuous arable cultivation (AL). Fallow soils (FL) recorded high organic carbon, high soil water retention between -2 to -1500kPa and, high total residual pores. Infiltration model evaluation showed Kostiakov’s model was more efficient and proved to be an excellent predictor of infiltration over Philip’s model. This was manifested as Kostiakov’s model gave value closed to unity for coefficient of determination-r2 (0.96), Nash-Sutcliffe Efficiency-E (0.94) and lower value for Root Mean Square Error-RSME (22.37) and Coefficient of Variability-CV (6.76%). Applications of different spacing and nitrogen rates to JCL did not significantly influence most soil physical parameters within the three years of plantation establishment.
PHYSICAL QUALITY OF AN ALFISOL AS INFLUENCED BY CULTIVATION OF JATROPHA CURCAS L. AT SAMARU, NORTHERN NIGERIA
