Effect of Conservation Tillage on Soil and Water Quality

Abstract

Soil erosion from cropland has been recognized as a major problem in agricultural production. Conservation tillage is one of many conservation practices developed to reduce soil erosion. Meanwhile, many benefits from conservation tillage system beyond controlling soil loss have been reported. The objective of this work is to briefly review effect of conservation tillage on soil erosion and runoff, soil organic matter, selected soil physical properties, and water quality. Conservation tillage has inconsistent effects on surface runoff and soil loss due to differences in surface roughness and the rate of crop residue left on the soil surface. Increased soil organic carbon (SOC), mainly concentrated near soil surface, has been widely reported in the literature. However, SOC under conservation tillage is labile in topsoil and more recalcitrant in subsoil. Increased SOC leads to improved soil physical properties such as reduced bulk density, increased hydraulic conductivity and infiltration, and improved water retention capacity. Conservation tillage could improve water quality by reducing the total sediment, nitrate, ammonium, and phosphate in the runoff. However, conservation tillage may also facilitate nitrate leaching due to the increase of macropores in soil body.