اثرات تجمعي و باقي مانده مواد آلي بر نفوذپذيري يك خاك لوم رسي در اصفهان

Cumulative and residual effects of organic matter on infiltration rate of a clay loam soil in Isfahan

Organic fertilizers have an effective role in soil physical properties, increasing soil fertility and reduction of erosion. In this research, cumulative and residual effects of organic and chemical fertilizers were studied on soil infiltration rate by applying manure, sewage sludge and chemical fertilizer treatments, each with three replications. In manure and sewage sludge treatments, 25, 50 and 100 ton/ha, and in chemical fertilizer treatments 250 kg/ha were applied to plots for three consecutive years I n study the residual effects of these organic matters, they were applied to some plots for only one year and to another set of plots for two years. Nothing was added to control plots. Corn and wheat were grown in the plots. Infiltration rate was measured in the third year by double-rings method. Infiltration equations of Kostiakov, Kostiakov-Lewis, Horton and Singh and Yu and four combinations of these equations were fitted to the measured infiltration values. The results showed that in most cases, Singh & Yu equation fitted better than the other equations or combinations and its mean error for estimating instantaneous infiltration rate was the least. The worst fit was for Horton equation. Final infiltration rate (fe) in control treatment was 10.32 mm/hr. in chemical fertilizer treatment, addition of fertilizer for three years was effective in increasing ff. but the difference was insignificant with other years. fe value in manure treatments was more than control, and the differences were statistically significant. f, value of 100 ton/ha manure treatment in the third year (227.88 mm/hr) was the highest among all the treatments. In sewage sludge treatments, fe values were significantly different from control, and twice application resulted in higher fe value (103.21 mm/hr) with respect to once and three times application. Cumulative depth of infiltrated water was significantly different between all organic and chemical fertilizer treatments and the control.