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Abstrakt

Comparative Analysis of Infiltration Measurements of Two Irrigated Soils in Akure, Nigeria

Christopher O. Akinbile

Infiltration test on two irrigated soils was carried out to determine the infiltration rates of the soils for proper irrigation scheduling and planning at the Federal University of Technology Akure (FUTA). The soil samples were taken from Agricultural Engineering Demonstration and the University Research farms. Soil classification was carried out using USDA textural triangle and a double ring infiltrometer was constructed and installed in the soil for the tests. Two models: Kostiakov and Philips were used to predict infiltration and compared with actual field measurements From the analysis, the soils were classified as sandy loam with 49.0% sand, 24.5% silt and 26.5% clay. The higher constituent of sand enables higher infiltration rate. The measurements of the soil chemical properties showed that the soil had a pH of 6.59 that was almost neutral and therefore did not have adverse negative effect on crops grown on it. Organic matter was 2.61(mg/l), Nitrogen 2.20(kg), Phosphorus 2.36(kg), Sodium 1.30(Na/ml), Calcium 3.00(Ca/ml) and Magnesium 0.70(mg/l) respectively. All these mineral constituents are within tolerable limits in soil for optimum crop growth. The constants of linear regression of the infiltration rates were obtained using Kostiakov and Philips equations which were a=58.87, n=0.12 and b=–66.4 respectively for Agricultural Engineering Experimental farm. Kostiakov equation derived was Ft=58.87t0.167 while Philips equation was Ft= 58.87-0.5–66.4 for the soil from the same farm. The average infiltration rate for the Agricultural Engineering Experimental Farms was 32.50 cm/min, and the cumulative infiltrations were found to be 16.58 cm/min. As for the University research farm, the average infiltration rates and cumulative infiltration were 28.30 cm/min and 11.46 cm/min respectively. Kostiakov equation derived was Ft = 66.52t0.09 while that of Philips was Ft = 66.52t0.09 – 61.84. From the statistical analyses carried out, there were obvious differences among the treatments at 5% significance level. This result could be used to plan for good irrigation scheduling and also to advice farmers on the type of irrigation techniques to be adopted based on the prevailing soil and weather conditions of such locations.