Evaluating Influence of Different Cover Materials on Runoff and Sediment Loss from Bare Upland Soil Using Laboratory Rainfall Simulator

Abstract

The use of composted organic matter as soil surface cover is recently viewed as a potential application for erosion control similarly to straw cover. However, limited information on the effect of these cover materials on erosion from bare soil is available. This study evaluates two cover materials, rice straw and cattle manure compost, with a focus on the relationship between soil surface coverage (expressed in areal%) and soil loss from bare upland field. A clay loam Andisol was packed into a 1.2 m X 0.35 m X 0.12 m soil box with a slope of 14% and subjected to simulated rainfall of 45.1 mm hr-1 for 100 minutes. The soil surface was either left bare or was covered with rice straw (Oryza Sativa L.) or cattle manure compost at a surface coverage of 30 areal % for straw, 35 areal% for compost, and 60 areal% for both materials. During the simulated rainfall, surface runoff was periodically collected to determine sediment concentration and infiltration rate. As the coverage rate increased from 30 or 35 to 60 areal%, the straw and compost covers acted to significantly reduce the sediment concentration. The observed reduction in sediment loss from the covered soils resulted from the direct interception of raindrops and trapping of sediment by the cover ; however, neither cover material was able to reduce the runoff rate. The total runoff volume was higher for compost-covered soils than for bare or straw-covered soils. This result may reflect the development of a depositional crust over the soil surface. Such crusts formed in sediment-trap areas close to pieces of the covering material.