change of plot size

Changes in plot size can be determine its effects on parameters changes of runoff and soil loss. On the other hand, the generated runoff in eroded soils is one of the most important obstacles and challenges of human in conservation of water and soil resources and it is also a threat to well-being and life. One of the most important of controlled factors of surface runoff and increasing soil infiltration is the application of conditioners or amendment materials on soil. But it should be noted that the size change can also control the runoff and soil loss variations. Therefore, the present study was carried for the effect investigating of size change in laboratory plots in two sizes of 0.5 × 0.25 and 1 × 0.5 m2 using application of organic manure with rates of zero (control treatment) and 62.5 and 125 g m-2 (conservation treatment) on changing time to runoff, runoff coefficient, soil loss and sediment concentration. The obtained results showed that the plots with size of 0.5 × 0.25 m2 and the application of organic manure with rate of 62.5 g m-2 had the little effect on the increasing time to runoff compared to control treatment. But, time to runoff increased with increasing plot size and also rate of organic manure. The effect of plot size on parameters of runoff coefficient, soil loss and sediment concentration, organic manure on parameters of time to runoff, runoff coefficient and soil loss and interaction effect of size change and organic manure on parameter of soil loss was significant at level of 99 percent. Also, in plot with area of 1.0 × 0.5 m2, the changes of time to runoff and runoff coefficient, soil loss and sediment concentration for organic manure with rate of 125 g m-2 toward 62.5 g m-2 were 72.83, 53.52, -212.27 and -142.92 2.12 percent, respectively. While, the changes of studied parameters for plot of 0.5 × 0.25 m2 were 594.24, -212.63, 4.06 and 13.70 percent, respectively.