Effects of subsequent rainfall events on runoff and soil erosion components from small plots treated by vinasse

Abstract

Soil erosion control is the most essential principle for the sound utilization of soil and water. The application of soil amendments is considered as an appropriate and new strategy for soil erosion control. Despite the application of different amendments used for soil and water conservation, the durability of the effects of soil amendments during subsequent rainfalls has not been considered yet. The present study, therefore, aimed to analyze the effect of vinasse application as one of the important wastes of cane agro-industries on runoff and soil erosion components during subsequent rainfalls for a sandy clay loam soil sampled from the Alborz summer rangeland. The study was conducted under laboratory conditions using a field rainfall simulator and three small plots with a 20% slope in three replicates. The duration and intensities of rainfall were respectively designated as 15min for 50 and 90mmh−1 to one initial and four subsequent rainfalls. Experiments were then set up as a control and two treated plots with doses of 4.5 and 8lm−2 of vinasse subjected to one initial and four subsequent rainfalls, respectively. The results of the study indicated that the application of the different amounts of vinasse had negative effects on the runoff commencement time, coefficient, and volume during the subsequent rainfall with an intensity of 50mmh−1. While the application of both levels of vinasse decreased soil loss and sediment concentration and had negative effects on the runoff components during the subsequent rainfall with the intensity of 90mmh−1. A high dose of vinasse decreased soil loss and sediment concentration, whereas a low dose of vinasse increased soil loss and sediment concentration. Overall, the high level of vinasse controlled hydrologic parameters better than the low level of vinasse during subsequent rainfall with different intensities. The results also revealed a significant effect of rainfall sequence on runoff commencement time, runoff volume, runoff coefficient, and soil loss (P<0.01), and a non-significant effect (P=0.13) on sediment concentration. On the other hand, rainfall sequence increased runoff volume and soil loss, which pointed to the need of the reapplication of vinasse soil amendment after a few rainfall events for efficient soil and water conservation.