The effects of mulching with organic materials on the soil nutrient and carbon transport by runoff under simulated rainfall conditions

The aim of this study is to reveal the effects of different organic mulch materials and application at different rates on the transport of nitrate nitrogen (NO3), ammonium nitrogen (NH4+), total nitrogen (TN), phosphate phosphorus (PO4-3)and total organic carbon (TOC) by runoff under the laboratory conditions and determine whether they affect the pH and electrical conductivity (EC) values in runoff after the application. Three different organic mulch materials (dry weed, wheat straw, and peanut hay) were applied on experimental plots prepared using Cambisol soils developed on sedimentary bedrock under laboratory conditions at four different rates (0 t/ha, 2 t/ha, 4 t/ha, and 6 t/ha). The experimental plots were placed on a smooth surface with a 9% slope, and simulated rainfall was applied at an intensity of 97 mm/h for 1 h. Runoff was collected, and NO3, NH4+, TN, PO4-3, TOC, pH, and EC were analysed. According to the results, peanut hay and straw mulch applications reduced NH(4)(+)concentrations in runoff. The most effective mulch type in reducing NO3 concentration was straw mulch at a rate of 4 t/ha. All three mulch types increased the concentration of TN, TOC, and PO4-3 in runoff. The lowest TN transport in water was found in the plots with straw mulch at 4 t/ha. The lowest TOC transport was found in plots with mulch application at a rate of 2 t/ha. The minimum PO4-3 loss was found in dry weed mulch treatments at a rate of 2 t/ha. Mulch applications generally increased the pH and EC values of runoff. In general, straw mulch reducing nutrient and TOC transport by runoff, followed by dry weed mulch applications. The type and application rate of mulches should be chosen carefully in terms of protecting water resources.