Effect of wheat straw mulch application on soil and organic carbon loss in rainfed hill slope lands

In arid and semi-arid regions the precipitation occurs erratically, and often, with high intensity which causes sediment production and soil loss especially in the areas ploughed parallel to the hill slope direction. In such areas, we can reduce those undesirable effects through employing proper management method. In this survey the effect of two treatments of applying straw mulch in standard plots and over three slope classes of 0-12, 12-20, and 20-40 % with three replicates in the split plot format on the base of RCB design were compared. In all plots, the parallel plough to slope direction was done. After wheat cultivation, on the half of plots, straw mulch was applied uniformly by hand on the soil surface. After any rainfall events, the amount of sediment was measured. Results showed that application of straw mulch caused a reduction of about 36.9, 10.8, and 55.4 % soil loss in three slope classes compared to the plots without mulch application respectively. These amounts for organic carbon loss were 33.2, 7.1, and 29.43 %. Statistical analysis by SAS software showed that difference between two treatments for sediment and Organic Carbon was significant at 5% probability. These results show that straw mulch application can highly increase the infiltration and water absorption and reduce soil and O.C. loss. Also, it can prevent the reduction of soil fertility through reducing organic material loss.