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United States Department of Agriculture

Agricultural Research Service

2010 Annual Report

1a.Objectives (from AD-416)
Overall Project Goal: Develop long-term sustainable soil and crop management practices for the Central Great Plains Region (CGPR) and identify technologies that maximize the use of the region’s soil and water resources with minimal negative environmental impact. Objectives: 1. Develop adaptive management practices and document their benefits to optimize yield and enhance ecosystem services for CGPR dryland agricultural systems most vulnerable to potential adverse climate changes with an emphasis on precipitation and temperature. 2. Quantify microbial plant associations and their effects on plant productivity in no-till dryland cropping systems. 3. Develop best management practices for remediation/restoration of degraded soils in the CGPR. 4. Development of alternative bio-fuel specialty crops for incorporation into alternative dryland cropping systems. 5. Quantify how localized climate, topography, soils and management that vary across landscapes affect crop yields, carbon sequestration, and nutrient cycling for dryland agricultural systems and to develop adaptation options to mitigate risks for dryland cropping systems associated with climate change.

1b.Approach (from AD-416)
Field, and laboratory experiments and modeling efforts will be conducted to determine the adaptability of current dryland cropping systems to potential changes in climate (primarily drought resulting from declining precipitation and/or increases in evaporative demand) in the region. These experiments and modeling efforts will include studies to evaluate and test the adaptability of dryland crop rotations across a regional site network that varies in soil type, climate and elevation (topography). Experiments will include the effects of residue management, nutrient management and crop ecological management to maximize carbon fixation/sequestration and crop yield and to reduce dependence on pesticides and other ag-chemicals. The effect of rotation and soil management on soil chemical, physical and biological quality will be also quantified. Crop and soil simulation models will be calibrated/evaluated for prediction accuracy of yield and soil transformations using 102 years of climate data and multiple years of crop rotation results to extrapolate research at CGPRS to other locations in the region. Economic risk assessment of intensive dryland rotations will be calibrated to determine economic feasibility.

3.Progress Report
ARS Scientists at Akron, Colorado developed several new predictive mathematical relationships for incorporation into decision support tools for estimating yield water use relationships of dryland winter wheat, dryland corn and other crops. The use and application of these decision support tools have been shared formally and informally with farmers, extension personnel and other agricultural researchers in the region at several producer meetings and at field day events. The decision support tools are accessible to the public through our website. Much of the skip-row research is complete but, through collaborations with researchers at Colorado State University (CSU) and ARS scientists at Sydney, Montana, the research is continuing to develop. We are now evaluating skip-row planting in sorghum with row direction and are evaluating light reception with skip-row in dryland corn. The millet wheat crop sequence experiment is finished. The results are inconsistent with respect to seeing a major effect of the millet residue on wheat production. Water availability still seems (as might be expected) to be the primary driver for subsequent wheat yields. Several soil quality, soil organic matter and soil carbon summary manuscripts were published this past year by ARS Akron researchers in collaboration with regional university scientists in Kansas, Colorado and Nebraska. Eight refereed journal articles and several other minor publications were published this past year dealing with various aspects of dryland cropping systems. Topics published include: simulation model validation of dryland canola yields, regional soil quality evaluations as affected by no-tillage and cropping intensity, crop biomass removal effects on soil degradation, water use yield relationships of dryland corn, prediction of soil water storage in summer fallow, yields of skip-row planted corn and sorghum in dryland systems, soil fertility response relationships of triticale, wheat and dryland corn and spectral methods for characterizing soil C quality and crop shoot/root relationships.

1. New quantification of the soil degradation caused by harvesting crop biomass for bio-energy or other off farm uses. Crop residues have recently been seen as a resource for renewable energy production. Very few reports have documented the effect long-term crop-biomass removal has on the sustainability of the soil resource. ARS researchers at Akron, Colorado measured the long-term effect crop-biomass removal has on soil organic carbon, soil organic matter, and other soil properties associated with soil quality. Full removal of crop residues both under irrigated and limited irrigated conditions decreases soil carbon. The research showed that only irrigated continuous-corn provided enough crop biomass to allow some (about 20%) removal for off-farm uses. However, under semi-arid conditions, even with irrigation, biomass production could not justify greater than about 20% biomass removal before soil quality for future generations will be compromised. We reported that removal of significant amounts of crop residue, even under irrigated conditions, detrimentally effects soil physical and chemical properties due to loss of soil carbon.

2. New predictive relationships for dryland corn as affected by soil water at planting and growing season precipitation. ARS researchers at Akron, Colorado developed 2 linear relationships that predict dryland corn yield based on amount of precipitation falling between 16 July and 26 August. These two relationships explained 87% of the variation in yield when available soil water at planting plus May precipitation, was greater than 10 inches and 93% of the variation in yield when available soil water at planting, including May precipitation was less than 10 inches. Prior to planting, risks associated with corn production in the Central Great Plains can be assessed using these relationships in conjunction with long-term precipitation records.

3. Field validation of existing Simulating models. ARS scientists at Akron, Colorado in collaboration with ARS colleagues in Fort Collins have documented/validated the usefulness of the CROPGRO-faba bean model for accurately simulating field measured yields of spring canola growth, development, water use, and yield. The model was implemented within both DSSAT 4.0 and RZWQM2 cropping systems simulation platforms permitting future assessment of canola productivity across the central Great Plains region and within potential new wheat-based crop rotations varying in cropping intensity. The simulation results confirm the potential for using RZWQM2 to simulate dryland crop yields under varying weather and soil conditions, and provide results that aid in the creation of decision support tools for dryland crop mnagement.

4. New documentation of soil attributes on root growth and distribution of common crops. ARS researchers at Akron, Colorado contributed to a summary and synthesis of knowledge on soil-root growth. Plant roots are the vital link between soil conditions and crop productivity. This effort summarizes current knowledge on the effects of soil physical properties on plant rooting, and provides a summary of current methods to quantify soil suitability for crop production. The research points out knowledge gaps in our understanding on how to model the root-soil interaction.

5. New quantification of the soil building benefits of long-term continuous cropping with reduced fallow frequency. ARS scientists at Akron, Colorado documented the soil building benefits of long-term intensive no-till dryland cropping systems. In the Central Great Plains much of the dryland cropping includes the old traditional wheat fallow (WF)system. The WF system fixes less atmospheric carbon and, in general, results in greater soil degradation than more intensive no-till systems. With many soils the WF system is not sustainable. The soil improving effects of 15 years of no-till intensive cropping significantly increased soil organic C (SOC), soil tilth (soil aggregates), and particulate organic matter (POM) relative to the conventional tilled WF-conventional-till, and even no-till WF-no-till. The research documents the rate of change in soil properties and SOC in the central Great Plains region; which is slow due to the dry conditions and low biomass production. Crop rotations that include a fallow period and/or tillage promoted SOC losses, thus slowing SOC accumulation and stable soil aggregate formation.

6. New chemical characterization of soil organic matter and soil organic carbon using quick methods of spectral analysis. Characterizing soil carbon quality is necessary in order to understand the stability of soil carbon under different agronomic conditions and climate scenarios. Typically these characterizations involve long-tedious methods of analysis using wet acid-base chemistry. ARS scientists at Akron, Colorado characterized soil organic matter quality (including humic and fulvic acids) and analyzed important soil organic matter fractions using new “quick methods” of infrared spectroscopy. They characterized soil carbon in different Corn Belt and Central Great Plains soils and in soils managed under alternative crop rotations in a semiarid climate. They documented the chemical differences in soil organic matter fractions as determined by these new spectral methods.

5.Significant Activities that Support Special Target Populations
Significant activities that support special target populations: Nearly all of our research is designed and focused to help small farmers in the four state area known as the Central Great Plains region (CGPR). Eighty-five to ninety-five percent of all the producers we interact with are small farmers as identified by the USDA criteria of under $250,000 annual gross receipts. Nearly all of the above accomplishments support the special target population known as small farmers. Our research is directed specifically to their needs. A close relationship exists between the research conducted by the ARS station at Akron and the needs of the customer/farmers who are the recipients of the results of that research. The unit hosted three summer field days that boast as many as 350 in (total) attendance. Nearly 80% of the attendees are producers, other attendees are ag consultants, Agri-business, NRCS and cooperative extension. We sponsored a winter tech-transfer meeting that had 370 in attendance from the four state region (almost 90% in attendance are producers). In addition the unit scientists were invited to present at several other regional field days in the 4 state region. This past year unit scientists participated in over 35 technology transfer events.

Review Publications
Harrington, J.E., Byrne, P.F., Peairs, F.B., Nissen, S.J., Westra, P., Ellsworth, P.C., Fournier, A., Mallory-Smith, C.A., Zemtra, R.S., Henry, W.B. 2010. Perceived Consequences of Herbicide-Tolerant and Insect-Resistant Crops on Integrated Pest Management Strategies in the Western United States: Results of an Online Survey. Ag Bioethics Forum Vol. 12(3&4)Article 16. Pages 1-17.

Nielsen, D.C., Vigil, M.F. 2010. Precipitation Storage Efficiency During Fallow in Wheat-Fallow Systems. Agronomy Journal. v.102(2)537-543.

Benjamin, J.G., Halvorson, A.D., Nielsen, D.C., Mikha, M.M. 2010. Crop Management Effects on Crop Residue Production and Changes in Soil Organic Carbon in the Central Great Plains. Agronomy Journal. 102:990-997.

Benjamin, J.G., Mikha, M.M. 2010. Predicting Winter Wheat Yield Loss from Soil Compaction in the Central Great Plains of the United States. Book Chapter:Land Degradation and Desertification: Assessment, Mitigation and Remediation 49:649-656. Doi: 10.1007/978-90-481-8657-0.

Humberto, B., Stone, L.R., Schlegel, A.J., Benjamin, J.G., Vigil, M.F., Stahlman, P.W. 2010. Continuous Cropping Systems Reduce Near-Surface Maximum Compaction in No-Till Soils. Agronomy Journal. 102:1217-1225. DOI:10.2134/agronj2010.0113.

Johnson, J.M., Papiernik, S.K., Mikha, M.M., Spokas, K.A., Tomer, M.D., Weyers, S.L. 2009. Soil Processes and Residue Harvest Management. In: Lal, R., Stewart, B.A., editors. Soil Quality and Biofuel Production. Advances in Soil Science. Boca Raton, FL: CRC Press. p. 1-44.

Nielsen, D.C., Halvorson, A.D., Vigil, M.F. 2010. Critical Precipitation Period for Dryland Maize Production. Field Crops Research 118:259-263. doi:10.1016/j.fcr.2010.06.004

Unger, P.W., Kirkham, M.B., Nielsen, D.C. 2010. Water Conservation for Agriculture. In: Zobeck, T.M., Schillinger, W.F., editors. Soil and Water Conservation Advances in the United States. Special Publication 60. Madison, WI:Soil Science Society of America, Inc. p. 1-45.

Last Modified: 11/26/2015
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