ARS | Publication request: Linking soil and water quality in conservation agricultural systems

Submitted to: Electronic Journal of Integrative Biosciences
Publication Type: Review Article
Publication Acceptance Date: May 20, 2008
Publication Date: December 29, 2008
Citation: Franzluebbers, A.J. 2008. Linking soil and water quality in conservation agricultural systems. Electronic Journal of Integrative Biosciences. 6:15-29.

Interpretive Summary: Soil and water resources are fundamental components of agriculture. Soil quality can be determined by observing the functionality of soil after being subjected to different types of management. Some key functions of soil are (a) to supply nutrients to plants, (b) to allow rainfall to penetrate soil and provide water to roots, (c) to successfully filter contaminants and nutrients from water passing through soil prior to entry into groundwater, (d) to sequester carbon dioxide from the atmosphere and store C in soil organic matter, and (e) to decompose organic matter and various man-made chemicals to avoid plant and animal toxicities. Soil organic matter is a key soil property that drives many of these important soil functions, and therefore, soil organic matter is an essential component of soil quality evaluation. Conservation agricultural management (i.e., conservation tillage, cover crops, and perennial pastures) helps to build soil organic matter. A scientist from the USDA-Agricultural Research Service in Watkinsville Georgia reviewed the literature and summarized soil and water quality responses from various conservation agricultural systems. The concentration of surface soil organic matter provided an excellent indication of the capacity of soil to allow rainfall to penetrate soil, as well as to reduce the nutrient content of water running off of the land. A direct linkage is suggested between surface soil organic matter accumulation and the potential of conservation agricultural systems to improve water quality. This concept applies to the >100 million acres currently farmed with conservation tillage and the >100 million acres of pastureland in the USA.

Technical Abstract: Soil and water resources are fundamental components of agriculture. Successful utilization of these resources for sustainable agricultural production is partly dependent upon how they are conserved. Soil quality is generally defined by how well soil functions under a given set of environmental conditions, as well as by its intended use. Soil organic matter is a key property that drives many important soil functions, e.g. supplying and cycling of nutrients, receiving rainfall and storing water for plants, filtering water on its passage to groundwater, sequestering C from the atmosphere, and decomposing organic matter and xenobiotics. Conservation agricultural systems (i.e., conservation tillage, cover crops, and pastures) that have high surface-soil organic C are highly effective in improving surface soil properties, which can have direct impacts on reducing water runoff volume and improving water quality. This review of the literature draws attention to the important linkage that surface soil organic matter brings to soil and water quality. Soil organic matter stratification with depth provides a buffer to maintain soil and water quality against “normal” perturbations in agricultural systems. Issues of concern still remain with unusually high nutrient applications to soil, such as caused by high N input with subsequent leaching of nitrate to groundwater and high P input with subsequent dissolved P in water runoff. A multidisciplinary approach is needed to better quantify the changes in soil and water quality between current management and the plethora of alternative management systems aimed at conserving soil and water resources.