This essay summarizes deliberation by the Soil Science Society of America (SSSA) Ad Hoc Committee on Soil Quality (S-581) and was written to spur discussion among SSSA members. Varying perceptions of soil quality have emerged since the concept was suggested in the early 1990s, and dialogue among members is important because, unlike air and water quality, legislative standards for soil quality have not been and perhaps should not be defined. In simplest terms, soil quality is "the capacity (of soil) to function". This definition, based on function, reflects the living and dynamic nature of soil. Soil quality can be conceptualized as a three-legged stool, the function and balance of which requires an integration of three major components-sustained biological productivity, environmental quality, and plant and animal health. The concept attempts to balance multiple soil uses (e.g., for agricultural production, remediation of wastes, urban development, forest, range, or recreation) with goals for environmental quality. Assessing soil quality will require collaboration among all disciplines of science to examine and interpret their results in the context of land management strategies, interactions, and trade-offs. Society is demanding solutions from science. Simply measuring and reporting the response of an individual soil parameter to a given perturbation or management practice is no longer sufficient. The soil resource must be recognized as a dynamic living system that emerges through a unique balance and interaction of its biological, chemical, and physical components. We encourage SSSA members to consider the concept of soil quality (perhaps as a marketing tool) and to debate how it might enable us to more effectively meet the diverse natural resource needs and concerns of our rural, urban, and suburban clientele of today and tomorrow. I NQUIRIES from policymakers, natural resource conservationists, scientists, and administrators regarding the concept of soil quality increased rapidly after the National Academy of Sciences published the book entitled Soil and Water Quality: An Agenda for Agriculture (National Research Council, 1993). In response, Dr. L.P. Wilding, 1994 president of the SSSA, appointed a 14-person committee (S-581) with representatives from all divisions. Appointees were asked to define the concept of soil quality, examine its rationale and justification, and identify the soil and plant attributes that would be useful for describing and evaluating soil quality. The SSSA president and members accepting this committee appointment recognized the emotion and high public visibility being attached to the subject. Simultaneously, several committee members were being asked

Biochar, a co-product of thermochemical conversion of lignocellulosic materials into advanced biofuels, may be used as a soil amendment to enhance the sustainability of biomass harvesting. We investigated the impact of biochar amendments (0, 5, 10, and 20 g-biochar kg− 1 soil) on the quality of a Clarion soil (Mesic Typic Hapludolls), collected (0-15 cm) in Boone County, Iowa. Repacked soil columns were incubated for 500 days at 25 °C and 80% relative humidity. On week 12, 5 g of dried and ground swine manure was incorporated into the upper 3 cm of soil for half of the columns. Once each week, all columns were leached with 200 mL of 0.001 M CaCl2. Soil bulk density increased with time for all columns and was significantly lower for biochar amended soils relative to the un-amended soils. The biochar amended soils retained more water at gravity drained equilibrium (up to 15%), had greater water retention at − 1 and −5 bars soil water matric potential, (13 and 10% greater, respectively), larger specific surface areas (up to 18%), higher cation exchange capacities (up to 20%), and pH values (up to 1 pH unit) relative to the un-amended controls. No effect of biochar on saturated hydraulic conductivity was detected. The biochar amendments significantly increased total N (up to 7%), organic C (up to 69%), and Mehlich III extractable P, K, Mg and Ca but had no effect on Mehlich III extractable S, Cu, and Zn. The results indicate that biochar amendments have the potential to substantially improve the quality and fertility status of Midwestern agricultural soils. RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. Biochar, a co-product of thermochemical conversion of lignocellulosic materials into advanced biofuels, may be used as a soil amendment to enhance the sustainability of biomass harvesting. We investigated the impact of biochar amendments (0, 5, 10, and 20 g-biochar kg − 1 soil) on the quality of a Clarion soil (Mesic Typic Hapludolls), collected (0-15 cm) in Boone County, Iowa. Repacked soil columns were incubated for 500 days at 25°C and 80% relative humidity. On week 12, 5 g of dried and ground swine manure was incorporated into the upper 3 cm of soil for half of the columns. Once each week, all columns were leached with 200 mL of 0.001 M CaCl 2 . Soil bulk density increased with time for all columns and was significantly lower for biochar amended soils relative to the un-amended soils. The biochar amended soils retained more water at gravity drained equilibrium (up to 15%), had greater water retention at − 1 and −5 bars soil water matric potential, (13 and 10% greater, respectively), larger specific surface areas (up to 18%), higher cation exchange capacities (up to 20%), and pH values (up to 1 pH unit) relative to the un-amended controls. No effect of biochar on saturated hydraulic conductivity was detected. The biochar amendments significantly increased total N (up to 7%), orga...

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Application of biochar to highly weathered tropical soils has been shown to enhance soil quality and decrease leaching of nutrients. Little, however, is known about the effects of biochar applications on temperate region soils. Our objective was to quantify the impact of biochar on leaching of plant nutrients following application of swine manure to a typical Midwestern agricultural soil. Repacked soil columns containing 0, 5, 10, and 20 g-biochar kg− 1-soil, with and without 5 g kg− 1 of dried swine manure were leached weekly for 45 weeks. Measurements showed a significant decrease in the total amount of N, P, Mg, and Si that leached from the manure-amended columns as biochar rates increased, even though the biochar itself added substantial amounts of these nutrients to the columns. Among columns receiving manure, the 20 g kg− 1 biochar treatments reduced total N and total dissolved P leaching by 11% and 69%, respectively. By-pass flow, indicated by spikes in nutrient leaching, occurred during the first leaching event after manure application for 3 of 6 columns receiving manure with no biochar, but was not observed for any of the biochar amended columns. These laboratory results indicate that addition of biochar to a typical Midwestern agricultural soil substantially reduced nutrient leaching, and suggest that soil-biochar additions could be an effective management option for reducing nutrient leaching in production agriculture. RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. Application of biochar to highly weathered tropical soils has been shown to enhance soil quality and decrease leaching of nutrients. Little, however, is known about the effects of biochar applications on temperate region soils. Our objective was to quantify the impact of biochar on leaching of plant nutrients following application of swine manure to a typical Midwestern agricultural soil. Repacked soil columns containing 0, 5, 10, and 20 g-biochar kg − 1 -soil, with and without 5 g kg − 1 of dried swine manure were leached weekly for 45 weeks. Measurements showed a significant decrease in the total amount of N, P, Mg, and Si that leached from the manure-amended columns as biochar rates increased, even though the biochar itself added substantial amounts of these nutrients to the columns. Among columns receiving manure, the 20 g kgbiochar treatments reduced total N and total dissolved P leaching by 11% and 69%, respectively. By-pass flow, indicated by spikes in nutrient leaching, occurred during the first leaching event after manure application for 3 of 6 columns receiving manure with no biochar, but was not observed for any of the biochar amended columns. These laboratory results indicate that addition of biochar to a typical Midwestern agricultural soil substantially reduced nutrient leaching, and suggest that soil-biochar additions could be an effective management option for reducing nutrient leaching in ...

Sustainable aboveground crop biomass harvest estimates for cellulosic ethanol production, to date, have been limited by the need for residue to control erosion. Recently, estimates of the amount of corn (Zea mays L.) stover needed to maintain soil carbon, which is responsible for favorable soil properties, were reported (5.25-12.50 Mg ha 21 ). These estimates indicate stover needed to maintain soil organic carbon, and thus productivity, are a greater constraint to environmentally sustainable cellulosic feedstock harvest than that needed to control water and wind erosion. An extensive effort is needed to develop advanced cropping systems that greatly expand biomass production to sustainably supply cellulosic feedstock without undermining crop and soil productivity.