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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
2009 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
First year plant population and yield data were obtained for biochar plots established in 2007. This data showed a substantial increase in plant population and a small but statistically significant increase in corn yields for the biochar amended plots. These biochar field plots are now in their second year of production. Several years of field data will be required before definitive information on the impact of biochar on soil quality, crop yields, and carbon sequestration can be determined. Twelve new biochar plots were established in the Fall 2008. The plots are part of a six-location plot trial coordinated under the Agricultural Research Service (ARS) Biochar and Pyrolysis Initiative. The new study is evaluating the impact of interactions between manure and biochar on soil quality and crop productivity. Analysis of soil and water samples for the 500-day soil column study designed to quantify the impact of biochar on soil quality, carbon sequestration, emissions of greenhouse gasses and nutrient concentrations in leachate from the columns was completed. Statistical analysis of the data and preparation of manuscripts for publication is under way. A manuscript documenting research on interactions among cation exchange reactions and the sorption of organic molecules by soil clays was published. The report includes a new conceptual model explaining the observed interactions among cations, organic molecules, and soil clay minerals. These interactions have a large influence on soil fertility, the fate of contaminants in soils, and the formation and stabilization of soil organic matter. Work on Near Infared Spectroscopy soil probe system was suspended in 2008 to allow for greatly expanded research on biochar impacts on soil and environmental quality. New analytical tools for the analyses of amino acids and amino sugars, phenolic acids, and carbohydrates in soils are essential for meeting Objectives 1A and 1D. Limitations of recently developed analyses for amino compounds and carbohydrates were identified and resolved. These techniques were used in conjunction with phenols analysis to i) measure degradation rates of plant biomolecules through an international collaboration in Costa Rica, and ii) identify the effects of no-tillage on the accumulation of soil carbon forms in an Arkansas rice soil. Field testing of a promising humic product was begun. In coordination with the manufacturer and distributor, ARS staff are measuring corn growth, nutrient uptake, and grain yield when the product was applied at different crop growth stages in four fields. The same measurements will also be taken in several tens of farmers’ fields across Iowa where the product was applied at one time in each field. The analysis for the study with two of the monofunction probes (commercial Hydra probe, and homemade 12-wire probe) is complete and a manuscript is in review. This year we finished lab analysis from Iowa forest site and from the Texas sites and the synthesis of all the data was completed. The dielectric properties agreed well between the two probes, but the bulk soil electrical conductivity from the Hydra probe needed to be recalculated with alternate equations.


4.Accomplishments
1. Soil biochar amendments reduce leaching of nutrients from soils. Loss of plant nutrients from soils due to leaching is both an economic loss to farmers and may adversely impact water quality in local streams and reservoirs. A 45-week soil column leaching study conducted as part of the ARS Biochar and Pyrolysis Initiative has shown that biochar applications on a typical Midwestern agricultural soil substantially reduced the leaching of several nutrients following the application of swine manure to the soil. Incorporation of 2% biochar produced by slow pyrolysis of hardwood lumber into the soil reduced leaching loss of nitrogen by 11% and leaching loss of phosphorous by up to 69%. The soil biochar applications also reduced leaching of calcium, magnesium, sodium, potassium, and silicon. By helping to keep these nutrients in the soil, biochar helps to improve both nutrient use efficiency and reduces the risk that the nutrients will contaminate surface and ground water. Biochar is a co-product of the pyrolysis platform for producing renewable energy products from biomass. The results suggest that adding biochar to soils may enhance the sustainability of the emerging bioenergy industry.

2. Comparison of the Hydra probe with a 12-wire probe for evaluating soil dielectric properties. The Hydra probe is a commercial probe for determining soil water content and electrical conductivity from measured electrical properties, but its function in a variety of soils still needed to be tested. We collected undisturbed soil samples from five states each with soil and management variables. Electrical properties were determined for a range of water contents and two temperatures with the two probes. The dielectric values were similar between the two probes, but the electrical conductivity determined by the Hydra probe needed a correction. Correct electrical conductivity values can now be determined with the Hydra probe using our equations.

3. Determination of decomposition rates of common plant biomolecules in tropical forest soils. Tropical forests have high potential for soil carbon sequestration on a global scale, yet knowledge is limited regarding the cycling and sequestration rates of specific carbon compounds in their soils. Using recently developed analyses for phenols, amino acids, amino sugars, and carbohydrates, we studied the soil retention of model compounds that were added to test plots in a Costa Rica forest. In combination with soil microbial respiration measurements by a collaborator, our results suggested that plant biomolecules have considerably different relative stabilities in tropical forest soils than they do in temperate climate soils. These results will help us better understand soil carbon sequestration in tropical forest soils, which will lead to better soil management for enhanced carbon sequestration.


6.Technology Transfer

Number of Other Technology Transfer2

Review Publications
Olk, D.C., Jimenez, R.R., Moscoso, E., Gapas, P. 2009. Phenol accumulation in a young humic fraction following anaerobic decomposition of rice crop residues. Soil Science Society of America Journal. 73(3):943-951.

Olk, D.C. 2008. Improved analyses for soil carbohydrates, amino acids, and phenols: Tools for understanding soil processes. Soil Science Society of America Journal. 72(6):1672-1682.

Logsdon, S.D. 2009. Water content reflectometer calibration, field versus laboratory. Soil Science Society of America Journal. 73(1):1-6.

Russell, A.E., Cambardella, C.A., Laird, D.A., Jaynes, D.B., Colvin, T.S., Meek, D.W. 2009. Nitrogen Fertilizer Effects on Soil Carbon Balances in Midwestern U.S. Agricultural Systems. Ecological Applications. 19(5):1102-1113.

Mao, J., Olk, D.C., Fang, X., He, Z., Schmidt-Rohr, K. 2008. Influence of animal manure application on the chemical structures of soil organic matter as investigated by advanced solid-state NMR and FT-IR spectroscopy. Geoderma. 146(1-2)353-362.

Logsdon, S.D., Mbuya, O.S., Tsegaye, T. 2008. Bulk Density and Soil Moisture Sensors. In: Soil Science: Step-by-Step Field Methods. Madison, WI: Soil Science Society of America. p. 211-220.

Chatterjee, R., Laird, D.A., Thompson, M. 2008. Interactions among K+-Ca2+ Exchange, Sorption of m-Dinitrobenzene, and Smectite Quasicrystal Dynamics. Journal of Environmental Science and Technology. 42(24):9099-9103.

Laird, D.A., Thompson, M. 2009. The Ultrastructure of Clay-Humic Complexes in an Iowa Mollisol. In: Laird, D.A., Cervini-Silva, J., editors. Carbon Stabilization by Clays in the Environment: Process and Characterization Methods, CMS Workshop Lectures, Volume 16. Chantilly, VA: Clay Minerals Society. p. 95-118.

Laird, D.A., Koskinen, W.C. 2008. Triazine Soil Interactions. In: LeBaron, H., editor. The Triazine Herbicides. St. Louis, MO: Elsevier Science. p. 275-299.

Lehmann, J., Czimczik, C., Laird, D.A., Sohi, S. 2009. Stability of Biochar in Soil. In: Lehmann, J., Stephen, J., editors. Biochar for Environmental Management. Chapter 11. London, England: Earthscan. p. 169-182.

Novak, J.M., Busscher, W.J., Laird, D.A., Ahmedna, M., Watts, D.W., Niandou, M. 2009. Impact of biochar amendment on fertility of a southeastern Coastal Plain soil. Soil Science 174(2):105-112.

Last Modified: 4/19/2014
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