Improving Soil Quality for Sustainable Production Systems?

Abstract

Human efforts to produce ever-greater amounts of food leave their mark on our environment. Persistent use of conventional farming practices based on extensive tillage, especially when combined with removal or in situ burning of crop residues, have magnified soil erosion losses and the soil resource base has been steadily degraded (Montgomery 2007). Many soils have been worn down to their nadir for most soil parameters essential for effective, stable and sustainable crop production, including soil physical, chemical and biological factors. Kaiser (Science 11 June 2004 p 1617) summarized the effect of land degradation on crop production. Lester Brown (as cited by Kaiser 2004) estimated that human activity was responsible for the loss of 26 billion tons of topsoil per year, 2.6 times the natural rate. Pimentel et al. (1995) estimated that in the United States erosion inflicted $44 billion a year in damage to farmland, waterways, infrastructure, and health. He predicted that if farmers failed to replace lost nutrients and water, U.S. crop yields would drop 8% per year. Even in high yielding areas where soils are not considered to be degraded, crops require an ever-increasing input to maintain yields. Despite the availability of improved varieties with increased yield potential, the potential increase in production is generally not attained because of poor crop management (Reynolds and Tuberosa 2008). Another direct consequence of farmers' persistent use of traditional production practices is rapidly increasing production costs associated with the inefficient use of inputs whose costs continue to rise. In addition, any new, more sustainable management strategy must be compatible with emerging crop diversification policies that may evolve to meet new consumer or industrial requirements. All of this must be accomplished within a scenario of decreasing area available for crop production because of urbanization and industrial expansion and the recent dramatic increases in the use of land for biofuel and industrial crop production, instead of for food.