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United States Department of Agriculture

Agricultural Research Service

Research Project: BIOGEOCHEMICAL PROCESSES INFLUENCING FORMATION AND STABILIZATION OF SOIL ORGANIC MATTER AND SOIL STRUCTURE
2011 Annual Report


1a.Objectives (from AD-416)
1)Develop a mechanistic understanding of processes controlling the formation and stabilization of organic matter in soils that enhance stabilization of soil structure. a) Determine the relative contributions of biochemical compounds to aggregation and C sequestration. b) Determine the role of clay minerals and charcoal in the formation and stabilization of soil organic matter and soil structure. c) Determine the nature of reactions between smectites and pesticides. d) Determine the effects of anaerobic soil conditions on biochemical processes that influence soil nutrient cycling. e) Develop integrative methods for fractionating SOM into meaningful pools..
2)Develop tools for in situ assessment of soil organic carbon and soil structure. a) Develop a multi-function probe (electrical and thermal properties) to evaluate soil structure. b) Develop and evaluate a field mobile NIRS tool for sensing soil carbon and various soil properties.


1b.Approach (from AD-416)
Field plot and column leaching studies will be used to quantify the impact of adding charcoal to soils on nutrient cycling, soil productivity, C sequestration, pesticide leaching, and on the formation and stabilization of clay-humic complexes. Interactions between selected pesticides and reference clays will be investigated to elucidate bonding mechanisms between organic molecules and clay surfaces. Seasonal patterns for cycling of phenolic and organic nitrogen compounds will be compared for routinely flooded and non-flooded soils. Anticipated products will include more accurate predictions of how crop and soil management effect nutrient cycling and soil organic matter stabilization. We will develop and test electrical and thermal soil probes to characterize soil structure. A regional non-linear multivariate calibration model for a recently developed on-the-go in situ near infrared diffuse reflectance soil probe will be evaluated to determine if the system can accurately map the spatial distribution of numerous soil properties (organic C, total N, CEC, moisture, buffer pH, and extractable nutrients) at the field scale.


3.Progress Report
This is the final report for the project 3625-11120-003-00D which terminated in April 2011 and was replaced by project 3625-12000-013-00D. During its five-year life-cycle, long-term sustainable corn stover harvest studies were initiated, effects of biochar were quantified in field and laboratory studies, the field efficacy of a humic product was evaluated, and laboratory procedures were developed to quantify several soil biochemical compounds and to separate soil organic matter fractions based on their relative age. These procedures were then used to determine chemical differences between soil aggregate fractions, the benefits of soil aeration on rice production and soil properties, and the effects of a rye cover crop on soil carbon accumulation. The stover harvest treatments included collecting (1) all standing plant material above a stubble height of 10 cm, (2) the upper half by height (ear shank upward), (3) the lower half by height (from the stubble to the earshank), or (4) no removal. Collectable biomass from Treatment 2 averaged 1.7 (±0.4) tons/acre for five years of continuous corn and 2.1 (±0.2) tons/acre for three years of rotated corn. Compared to harvesting only corn grain, collecting stover increased the average nitrogen-phosphorus-potassium (N-P-K) removal by 26, 3, and 30 pounds/acre for continuous corn and 37, 3, and 30 pounds/acre for rotated corn, respectively. Approximately eight acres of land were treated with 0, 8,800, or 16,000 pounds/acre of hardwood biochar as part of the sustainable corn stover feedstock project. The three-year average grain yields for the four treatments were not statistically different. There were no beneficial or detrimental plant nutrition effects in the three years following char application, nor detectable tillage energy (draft) effects when measured in the spring of 2010. Laboratory studies with the same biochar showed decreased soil compaction, increased soil acidification (pH), and increased capacity of soil to hold water and plant nutrients compared to soils that did not receive biochar. The divergence in results between field and laboratory studies needs explanation and the economic viability of char needs to be demonstrated. To identify parameters of soil carbon sequestration that are more sensitive to crop management practices than is total carbon, the sizes and compositions of young soil organic matter fractions were determined using a novel sequence of floating, sieving, and chemical extraction steps. The compositions of these fractions showed that a winter rye cover crop promoted early season accumulation of young organic matter, including accumulation of specific carbohydrates and most amino acids. A humic product was applied in test strips of corn production in 25-30 farmers’ fields. Product application resulted in a significant increase in grain weight. The value of the increased grain yield far exceeded the cost of the material. The overall impact of this project was long-term evaluation of management practices for improved corn production while maintaining soil quality and nutrient contents.


4.Accomplishments
1. Sustainable production of corn feedstock. In addition to being a potential feedstock for biofuel production crop residues already protect the soil from wind and water erosion, renew the supply of soil organic matter, and provide a food source for earthworms and other soil organisms. What we do not know is how harvesting crop residues for bioenergy production will affect soil quality and these other ecosystem services that are essential for sustaining soil, water, and air resources. Five years of field research by Agricultural Research Service (ARS) scientists near Ames, IA, indicates that harvesting 1.0 to 2.0 tons/acre of corn stover as feedstock for bioenergy or other uses is sustainable and can be achieved by using cover crops, no-tillage practices, crop rotation, routine soil-testing, plant analysis, and other best management practices to select appropriate harvest sites. These results are being used by various stakeholders (e.g., POET, DuPont Danisco Cellulosic Ethanol [DDCE], and the Council for Sustainable Biomass Production [CSBP]) as they develop plans and facilities for cellulosic biofuel production with crop residues that are scheduled to become operational in 2013 and 2014.

2. Humic products can increase corn production. The term “humic product” refers to various substances obtained from decomposing vegetative and animal matter (i.e., humus). These materials occur naturally in soils, but have also been promoted as a commercial additive to enhance crop production. Currently, very little formal evidence exists to support claims by humic product manufacturers that their materials increase crop yields enough to offset the increased production costs. Agricultural Research Service (ARS) researchers in Ames, IA, evaluated the effects of one humic product on corn production in farmers’ fields. In most cases, plant growth was significantly improved during the growing season and grain weights increased modestly (<10%) but significantly. Acquired information helped identify situations where the humic product is most or least likely to increase grain yield. These results indicate the potential of humic products to increase crop production without additional input of water or fertilizers.


Review Publications
Karlen, D.L., Varvel, G.E., Johnson, J.M., Baker, J.M., Osborne, S.L., Novak, J.M., Adler, P.R., Roth, G., Birrell, S. 2010. Monitoring soil quality to assess the sustainability of harvesting corn stover. Agronomy Journal. 103:288–295.

Imaz, M.J., Virto, I., Bescansa, P., Enrique, A., Fernandez-Ugalde, O., Karlen, D.L. 2010. Tillage and Residue Management Effects on Semi-Arid Mediterranean Soil Quality. Soil & Tillage Research. 107:17–25.

Laird, D.A., Fleming, P.D., Karlen, D.L., Wang, B., Horton, R. 2010b. Biochar Impact on Nutrient Leaching from a Midwestern Agricultural Soil. Geoderma. 158:436-442.

Karlen, D.L., Dinnes, D.L., Singer, J.W. 2010. Midwest soil and water conservation: Past, present and future. In: Zobeck, T.M., Schillinger, W.F., editors. Soil and Water Conservation Advances in the U.S.: Past Efforts and Future Outlook. Madison, WI: Soil Science Society of America, Inc. p. 131-162.

Wilhelm, W.W., Johnson, J.M., Lightle, D., Karlen, D.L., Novak, J.M., Barbour, N.W., Laird, D.A., Baker, J.M., Ochsner, T.E., Halvorson, A.D., Archer, D.W., Arriaga, F.J. 2011. Vertical distribution of corn stover dry mass grown at several U.S. locations. BioEnergy Research. 4(1):11-21.

Hess, J.R., Jacobson, J.J., Karlen, D.L., Muth, D.J., Nelson, R.G., Ovard, L.P., Searcy, E.M., Ulrich, T.H. 2010. Agriculture and land use issues. In: Rosillo-Calle, Frank and Johnson, Francis X, editors. Food versus Fuel: An Informed Introduction to Biofuels. London, UK: Zed Books Ltd. p. 86-115.

Malone, R.W., Jaynes, D.B., Ma, L., Nolan, B., Meek, D.W., Karlen, D.L. 2010. Soil-test N recommendations augmented with PEST optimized RZWQM simulations. Journal of Environmental Quality. 39:1711-1723.

Laird, D.A., Fleming, P.D., Davis, D.D., Horton, R., Wang, B., Karlen, D.L. 2010a. Impact of Biochar Amendments on the Quality of a Typical Midwestern Agricultural Soil. Soil Science Society of America Journal. 158:443-449.

Johnson, J.M., Wilhelm, W.W., Karlen, D.L., Archer, D.W., Wienhold, B.J., Lightle, D.T., Laird, D.A., Baker, J.M., Ochsner, T.E., Novak, J.M., Halvorson, A.D., Arriaga, F.J., Barbour, N.W. 2010. Nutrient removal as a function of corn stover cutting height and cob harvest. BioEnergy Research. 3:342-352.

Mao, J., Palazzo, D.C., Olk, D.C., Clapp, C.E., Senesi, N., Bushore, T.I., Cao, X. 2010. Chemical structure of soil organic matter in slickspots as investigated by advanced solid-state NMR. Soil Science. 175:329-338.

Karlen, D.L. 2011. Soil Tilth: What every farmer understands but no researcher can define. In: Glinski, J., Horabik, J., Lipiec, J., editors. Encyclopedia of Agrophysics. Heidelberg, London; New York: Springer Dordrecht. p. 794-798.

Sharma, S.K., Aketi, R., Sharma, M.P., Joshi, O., Govaerts, B., Steenwerth, K.L., Karlen, D.L. 2010. Microbial community structure and diversity as indicators for evaluating soil quality. Sustainable Agriculture. 5:317-358.

Last Modified: 7/25/2014
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