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Research Project: Stewardship of Upper Midwest Soil and Air Resources through Regionally Adapted Management Practices

Location: Soil Management Research

2019 Annual Report

1a. Objectives (from AD-416):
Objective 1: Evaluate conservation practices adapted for use in short-growing seasons to enhance soil quality, improve nutrient use efficiency and sustain agronomic productivity. Objective 2: Integrate soil and crop management practices that enable sustainable, climate-resilient agriculture for the Upper Midwest.

1b. Approach (from AD-416):
Two objectives are being addressed using a temporally-stratified and multi-faceted approach to select, evaluate and initiate integrated conservation practices for regional suitability. Data from seven long-term studies are providing the foundation for evaluating individual and integrated practices using statistical modeling and management assessment indices. These studies were designed with several types of conservation practices including tillage, conversion of perennials, including perennial in extended rotations, addition of cover crops and impacts of variable stover harvest rates. Each experiment study was set out as a randomized complete block or as a split plot – with randomized complete block within the spilt. All have four replications of each treatment. These long-term studies have SOC and corn grain yield data in common; so those variables will be used if conversion to 1) conservation tillage; 2) perennial grasses; or 3) including a winter rye cover crop increase SOC and if returning all crop biomass increases SOC compared harvesting stover. Soil quality assessment indices approach: Assessment one tests the hypothesis that soil quality assessment scores will be greater (indicting improved soil quality) following multiple years of deploying a conservation practice compared to business as usual. Assessment scores at two (or more) time points from existing datasets from the long term studies will be used to determine if soil quality appears to be aggrading, degrading or remaining the same over time. A second assessment will be made using data collected form a common future data set from studies that will have been in place at least 10 years compare treatments lacking conservation to treatments with one or more conservation practices deployed. Comparisons of management strategies will be made using a mixed model ANOVA procedure to assess soil scores among treatments. The ability of annual rye grass or forage radish to improve nutrient use efficiency in corn is being addressed. The null-hypotheses for this experiment are that yield, and N use of corn grown following cover crops (annual rye grass or forage radish) will not differ from corn grown without a preceding cover crop, and that the nitrogen fertilizer requirements will be similar for corn following wheat with or without a cover crop. Treatments were arranged in a replicated, randomized complete block design, which was blocked by field location and replicated four times. Cover crop shoot and root biomass, crop yield and N uptake, and soil N levels will be measured. Statistical analyses will analyze linear and quadratic effects of N treatments. Using a mixed-model ANOVA, cover crop will be treated as a fixed effect, N-rates as a continuous variable, and replication (within a site year) and site-year as random effects.

3. Progress Report:
We have made substantial progress in the evaluation of conservation practices from long-term studies (Goal 1.1). A publication was produced that contributed to better understanding of conservation practices that enhance soil quality, improve nutrient-use efficiency and sustain agronomic productivity. The data compiled for this publication were obtained from the Farming Systems Experiment conducted from 2002-2010. This completed effort is further addressed in the Accomplishments section of this report. Progress continues with another long-term study, which is a merging of a tillage experiment initiated in 1996, and an alternative biomass production system (ABP) comparison established in 2008. The tillage experiment continues as a comparison of no-tillage, strip-tillage and moldboard plow tillage in corn-soybean rotation systems. The ABP was established in the strip-tilled subset of the tillage experiment plots. The ABP is approaching the end of its third staggered 6-year rotation comparison of six alternative biomass production systems: (1) switchgrass for three years followed by soybean-corn-soybean (S-C-S), (2) grass mixture (switchgrass, big bluestem, Indian grass) for three years followed by S-C-S, (3) annual sorghum X Sudan grass (S/S) - S rotation, (4) C-S (corn-soybean) rotation with winter ryegrass cover crop following C, (5) C-S rotation with red-clover continuous living mulch, and (6) C-S rotation without cover crop. In fall of 2019, at the completion of this 12-year study, all treatments of the ABP and all other Tillage experiment treatments (no-till and moldboard till) will be sampled and analyzed primarily for changes in soil carbon status. In the following year, new treatments will be applied to full Tillage Experiment that will align with the Long Term Agroecosystem Research (LTAR) business as usual versus aspirational production practices. Substantial progress has been made to compile data from 1996 through the current year into a Data Entry Template for the GRACEnet/REAP data base so it is ready for the next data call. Progress continues on the carbon crop study, which is a long-term study established in 2000, to assess strategies for increasing soil C sequestration in a field managed without tillage. A total of twelve different strategies are being assessed. These strategies include extended crop rotations including a perennial legume (alfalfa), three-year rotation (corn-soybean-wheat), two-year C-S rotation with a cover crop, and perennial grasses managed a cellulosic biofuel. All agronomic samples collected in the fall of 2018 were processed and chemical analyses were conducted. Biomass Residue Return study is a three-field study that was established in 2005. Greenhouse gas emission data collected over three cropping seasons (planting to planting) from two of the study fields were published. The results documented that while nitrous oxide emission occurred in response to fertilizer application and during spring-thaw events, emission was not altered by the stover management. Long-term soil data from these plots were utilized in a modeling study and a metanalysis contributing to the understanding of how stover management impacts soil organic carbon and soil resilience. The soil sampling campaign in the NT2005 field scheduled for the fall of 2018 was postponed until the fall of 2020, because of the soil conditions after crop harvest were too wet. The fall of 2020 is the next time that the crop rotation will be in the desired crop phase. Data from this study is being analyzed using the SMAF tool, utilizing additional indices. The 2018 agronomic samples were collected, and chemical analyses completed. The 2019 season sampling is on-going. Objective 1.2. Statistical analyses and syntheses of a three-year study that evaluated the impact of two winter cover crops on nitrogen use in corn were completed. Manuscript preparation is on-going. In collaboration with scientists from the University of Minnesota, two experiments designed to evaluate cover crop variety options and planting methods, e.g., interseeding at various stages of crop development are in the third year of a multi-year study. Data contributed from published research to the nitrogen-use database "Nutrient Use and Outcome Network (NUOnet)" housed within the AgCros data repository. Objective 2. Significant progress has been made on understanding soil and crop management practices that enable sustainable, climate-resilient agriculture for the Upper Midwest. In collaboration with other scientists from other federal laboratories and universities meta-analyses of metanalysis contributing to the understanding of how stover management impact soil organic carbon, soil resilience. Work is underway for an additional metanalyses assessing the interaction of cover crops, manure and other organic amendments with corn stover management. Substantial progress was made to evaluate soil quality assessment scores from compiled data of long-term studies. Data from three long-term studies has been organized for conducting a soil quality assessment with the Soil Management Assessment Framework (SMAF) and calculating corresponding soil quality index scores. Statistical analyses and manuscript preparation are on-going. Substantial progress is being made on data synthesis based the Resilient Economic Agricultural Practices (REAP) cross location efforts. An integrated data set is nearly assembled, with on-going quality control and quality assurance. On a closely related effort, contributed to the work resulting in a published paper. The Morris location is part of the Long-Term Agroecosystem Research (LTAR) within the Upper Mississippi River Basin (UMRB) project area. We maintain and collect data from two Eddie Covariance (EC) towers located on a farm cooperator site. One flux tower is monitoring a business as usual field and one an aspirational farming system. Both locations are instrumented with phenocams. Additional data collected at the LTAR sites include micrometeorological data, soil samples, apparent electrical conductivity, combine yield, and RGB multispectral sUAS (drone) images. The Swan Lake Weather Station located at the Swan Lake Research Farm is part of the LTAR project and includes a phenocam taking images of plot-scale research. All phenocams are included in the National Phenocam Network. Two staff members are certified drone pilots. Weather data is automatically collected and transferred to the National Agricultural Library (NAL) in near-real time. Data sets are displayed graphically and made available to scientists across the nation on the NAL site. We are currently exploring a third on-farm research site with similar soils to install an additional EC system. Within, LTAR, the location is cooperating with several sub-groups or projects including the Phenocam Initiative, the UAV (drone) interest group, the Weather and Climate group, and the Data Management team.

4. Accomplishments
1. Spring camelina responses to nitrogen fertilizer in USA northern Corn Belt. Camelina is a source of industrial and food oils that can be grown in the USA. The seed oil is a feedstock for producing "green" jet fuel that meets all the ASTM standard for aviation fuel However, little was known about the nitrogen fertilizer needed to support growing camelina as a commercial oilseed crop. Nitrogen is critical for crop production, but if it is left behind in the soil can easily be lost over the winter. Plus, nitrogen fertilizer is an expensive input to producers so unused nitrogen represents reduction in potential profits. ARS researchers at Morris, Minnesota, conducted a two-year study measuring plant yield and the amount of nitrogen left in the soil was used to make a fertilizer recommendation that support crop yield without leaving excessive fertilizer behind. The data was added to the ARS Nitrogen Use and Outcomes (NUO net) database. This information is used for producers who wish to grow this crop and get the most use of the nitrogen applied.

2. Harvesting corn residues did not change nitrous oxide emission. Corn is one of the most common grown crops grown in the USA. It grows quickly and produces roughly equal amount of grain and residue. The residue also called stover is the non-grain material including leaves, cobs and stalks. Stover can be used to make fuel grade ethanol, but harvesting stover can change soil properties, which could also change how much nitrous oxide is released from soil. Nitrous oxide is potential greenhouse gas that contributes to global warming. ARS researchers in Morris, Minnesota, monitored the amount of nitrous oxide released from two fields. Nitrous oxide was released after applying nitrogen fertilizer and in the early spring when the soil is thawing. However, the same amount of nitrous oxide was released among the three stover harvest treatments. This means harvesting stover did not increase nor decrease how much of this gas was released. These results are important for the bioenergy industry, feedstock producers and for modelers seeking to understand what may happen as stover harvest become more common.

3. Understanding how managing corn residue impacts soil organic carbon modeling and metanalyses. The amount of corn residue that can be harvested without causing undesirable impacts on soil properties can be challenging. ARS researchers in Morris, Minnesota, used empirical data from long-term studies on the impact of corn residue harvest in a process-based model and as a part of a meta-data analysis. The meta-analyses suggested that soil organic content (a measure of soil health) was more sensitive to stover harvest rate than to tillage. These analyses can help determine science-based policy recommendations for harvesting crop residue for bioenergy.

4. Organic matter inputs are essential for reducing soil organic carbon (SOC) loss. Conservation production systems are needed in the upper Midwest to slow down soil and nutrient loss through tillage-induced erosion. However, due to the cool, wet climate, producers are reluctant to adapt strip-tillage or similar strategies that might prevent these losses. ARS researchers in Morris, Minnesota, compared change in SOC among a combination of tillage, rotation and fertilizer strategies. Loss of SOC occurred regardless of the type of tillage used; however, increasing residue inputs by using fertilizer reduced the amount of SOC lost. Organic fertilizer sources were better than inorganic fertilizer in maintaining SOC. Additionally, strip-tillage, four-year crop rotations, and organic fertilizer strategies benefited soil microbial populations. Using at least two of these three strategies can mitigate SOC loss and benefit soil microbes without compromising crop production. These results will help researchers, land managers and policy makers to develop, support and promote management strategies that target increased residue production through either improved yields or inputs from sources such as manure and cover crops.

5. Novel winter-hardy oilseeds help reduce nutrient loss. Winter cover cropping is a proposed strategy to reduce nutrient loss. However, establishing cover crop systems in the Upper Midwest is challenging due to lack of winter-hardy crop varieties and incentives for adoption. ARS researchers in Morris, Minnesota, determined that two novel over-wintering oilseed crops, winter camelina and pennycress, sequestered available N and reduced soil water nitrate from fall through spring soybean planting. These novel winter oilseeds provide an economic incentive for their adoption as they can be grown and harvested for their seed-oil. These results will help researchers, land managers and policy makers to develop, support and promote winter oilseeds as a cover cropping strategy that can provide both environmental and economic benefits.

Review Publications
Acosta Martinez, V., Perez-Guzman, L., Johnson, J.M. 2019. Simultaneous determination of ß-glucosidase, ß-glucosaminidase, acid phosphomonoesterase, and arylsulfatase in a soil sample for a biogeochemical cycling index. Applied Soil Ecology. 142:72-80.
Gollany, H.T., Nash, P.R., Johnson, J.M., Barbour, N.W. 2020. Predicted annual biomass input to maintain soil organic carbon under contrasting management. Agronomy Journal. 2020:1-14.
Johnson, J.M., Barbour, N.W. 2019. Stover harvest did not change soil nitrous oxide emissions in two Minnesota fields. Agronomy Journal. 111:143-155.
Johnson, J.M., Gesch, R.W., Barbour, N.W. 2018. Spring camelina N rate: Balancing agronomics and environmental risk in United States Corn Belt. Archives of Agronomy and Soil Science.
Weyers, S.L., Johnson, J.M., Archer, D.W., Forcella, F., Gesch, R.W. 2018. Manure and residue inputs maintained soil organic carbon in Upper Midwest conservation production systems. Soil Science Society of America Journal. 82:878-888.
Weyers, S.L., Thom, M.D., Forcella, F., Eberle, C.A., Matthees, H.L., Gesch, R.W., Ott, M., Feyereisen, G.W., Strock, J.S., Wyse, D. 2019. Potential for nutrient loss reduction in cover cropped systems in the Upper Midwest. Journal of Environmental Quality. 48(3):660-669.
Xu, H., Sieverding, H., Kwon, H., Clay, D., Stewart, C.E., Johnson, J.M., Qin, Z., Karlen, D.L., Wang, M. 2019. A global meta-analysis of soil organic carbon response to corn stover removal. Global Change Biology Bioenergy. 00:1-19.