Soil Quality Changes In Different Residue Management Systems Compared To Grassland After 22 Years
The objectives of this study are to:
(1) Measure the key chemical, physical and biological properties on a grassland area and on three long term 22-year residue management systems in a small grain-row crop rotation to determine the impact on soil quality;
(2) Determine carbon sequestration in the soil profile under the different systems; and
(3) Measure the evolution of carbon dioxide from the soil with the different systems under different N fertilizer variables over two different crop seasons.
Quality or health of our soils has gained attention due to recent environmental issues related to soil degradation and the impact on our water or air resources. There is also concern that some management practices do not maintain the sustainability or productive capacity of the soil and may raise food quality-safety issues for future generations. Health of an individual soil can be evaluated by measuring the impact of various management practices on the chemical, physical and biological properties over time. The essential property(s) selected may vary with soil texture, landscape position, climatic region and time. Therefore it is essential that soil quality be scientifically evaluated over a range of conditions. Soil aggregation, earthworm activity and organic matter, or more specifically soil organic carbon (SOC), are some properties specified as key indicators of soil health because these properties influence many of the other soil properties like infiltration, aeration and nutrient availability. Measuring SOC has gained additional support for evaluating soils because it is an indicator of carbon flux related to the carbon dioxide green house effect. Soils can act as either a sources or sinks for carbon dioxide in the air. Additions of carbon to the soil, and their sequestration, are controlled by management practices. The more carbon retained by the soil, the better the quality and sustainability of the soil. The impact of long term alternative production systems on both soil quality and carbon sequestration have been designated as high priority issues by organizations like Sustainable Agriculture Research and Education (SARE), government agencies like the Natural Resource Conservation Service (NRCS) and other federal and/or state agencies at the recent international symposium on carbon sequestration in soils and international soil conservation organization conference.
A long term (22 year) field research project comparing three different residue management systems in a small grain-row crop rotation will be compared to an adjacent grassland area with the same soils. The goal is to evaluate the impact of management systems on quality of the soil. Three soil scientists will conduct and/or supervise collection of soil and plant growth data, and will evaluate, summarize and publish the data. Soil samples at various profile depths will be collected at intervals over the two year study and will be analyzed for various chemical, physical and biological properties using standard procedures. Plant samples will be collected and analyzed for nutrients (NPK) to evaluate the dry matter and nutrient contribution or removal to the systems. Root samples will be collected to evaluate mycorrhizae colonization.
Replicated sample data will be statistically analyzed using analysis of variance, correlation and/or regression procedures. Information collected from the study will be prepared in a detailed final report upon completion of the study. Information will also be summarized in written, tabular or graphics forms for presentation at local, state or national meetings and outreach programs. Results will provide additional information on the long-term effects of various alternative management practices on soil quality factors and carbon pools under dryland conditions of the North Central Region. Results will also be used to select the key soil quality factors that researchers, producers and agency support groups can use for education and training in the evaluation of alternative management practices that change over time with advances in technology.