Location: Soil Management Research
2024 Annual Report
Objectives
Objective 1: Parameterize the magnitude, direction and stability of changes in key soil properties that are candidates for indicators of soil health and productivity in short and long-term experiments to develop high value soil health metrics for Upper Midwest producers.
1A: Use legacy and nascent data from past and on-going long-term field experiments (Table 1) to synthesize and understand soil chemical, physical and biological (i.e., soil health) properties with respect to direction, magnitude, and persistence of change.
1B: Assemble data and analyses from Goal 1A to develop a novel metric capable of evaluating soil health status with a limited number of necessary indicators that functions on a short-term scale.
Objective 2: Quantitatively assess the efficacy of common and aspirational agricultural practices to positively influence soil health and ecological/ecosystem services to guide development or enhance sustainable management practices for the Upper Midwest.
2A: Use eddy covariance tower data in combination with soil and agronomic data to evaluate CO2 flux and energy balances of two aspirational versus local BAU management systems.
Objective 3: Evaluate nutrient cycling within current and emerging cropping systems that are being employed or explored in the Upper Midwest to improve nutrient use efficiency approaches and to achieve desirable environmental outcomes.
3A: Evaluate nutrient availability and potential environmental quality benefits of winter cover crops and reduced tillage practices in comparison to a BAU conventionally tilled corn-soybean rotation.
Objective 4: Conduct research as part of the LTAR network, and in concert with similar long-term, land-based research infrastructure in the U.S, use the Northern Headwaters, MN LTAR site to improve the observational capabilities and data accessibility of the LTAR network and support research to sustain or enhance agricultural production and environmental quality in agroecosystems characteristic of the Northern Headwater. Research and data collection are planned and implemented based on the LTAR site application and in accordance with the responsibilities outlined in the LTAR Shared Research Strategy, a living document that serves as a roadmap for LTAR implementation. Participation in the LTAR network includes research and data management in support of the ARS GRACEnet and/or Livestock GRACEnet projects.
Approach
Three interrelated objectives will integrate science and stewardship to advance sustainable management practices for the Upper Midwest. Objective one, part one determines the impact of numerous conservation-oriented management strategies on soil health, productivity, and ecosystem services by using archived data and soil from seven on-going or terminated research experiments. Management factors compared include tillage strategies, rotation complexity, and cover crop or perennialized approaches. The main question addressed is: Does soil carbon increase over time when conservation approaches (such as reduced tillage) are used and is this positively related to sustained or improved crop productivity? Objective one, part two develops a soil health/sustainability metric to be derived by identifying the relationships between or among soil health indicators and yields or other recognized or novel indicators assembled from the data under part one. This will require a combination of scoring factors, geometric relationships, and advanced statistical approaches. The main goal of this metric is to be able to use (minimal or numerous) collected data to compare different management strategies to identify those strategies most likely leading to improved soil health or sustainability.
Objective two, comprised of three large-scale (>40 acres), on-farm experiments, compares aspirational practices (strip-tillage with a corn-soybean-wheat rotation, and strip tillage with a corn-soybean rotation) to traditional practices (deep ripping with a corn-soybean rotation) and contributes to USDA’s LTAR program that involves multiple USDA and University partnerships. Each field is instrumented with eddy covariance (CO2 flux) towers and other climate monitoring instruments. Soil properties, crop yields, and management inputs are monitored through time. The goal is to determine if aspirational practices lead to greater carbon sequestration (influx > efflux) and sustained/improved crop yields.
Objective three, a large-scale (80 main plots), long-term experiment initially established in 1996, compares three levels of tillage disturbance: high - moldboard plow, chisel, or disk tillage; reduced/moderate - strip-tillage; zero - no-tillage. To parallel the on-farm work under objective two, a corn-soybean/winter rye rotation comparison is included. The main goal is to determine if less tillage disturbance and/or a winter cover crop improves soil health while sustaining or improving crop yields. An additional goal is to evaluate the impact of these practices on the mobility or potential loss of nutrients (e.g., nitrates, soluble reactive phosphorus) to groundwater, which will be assessed with the use of suction cup lysimeters.
Progress Report
Objective 1: Efforts focused on the Long-Term Tillage Study (TS) established in 1997 and the Alternative Biomass Production Systems (ABP) project set within the TS from 2008-2020. Specific progress for Objective 1A was made by completing analyses that were delayed the previous year due to asbestos abatement, which limited access to analytical equipment. The yield analyses completed in 2023 were successfully presented at an international scientific conference at the beginning of this reporting year. These data, particularly the generalized yield decline over time, led to additional changes in management to incorporate more detailed fertility testing and tracking, and informed weed control, particularly within the unmanaged areas surrounding the experimental plots that was not previously seen as a point-source for weed influx.
Objective 2: Three Eddy Covariance (EC) towers located on two farm cooperator sites are operating as part of the croplands common experiment of the Long-term Agroecosystem Research (LTAR) - Upper Mississippi River Basin (UMRB) project. The business as usual (BAU) treatment is a corn/soybean rotation with aggressive tillage on a fully tile drained field and the two Aspirational treatments are ASP1- a corn/soybean rotation with shallow strip tillage and ASP2 – a corn/soybean/wheat with cover crops and shallow strip tillage. In 2024, BAU field is planted to corn. ASP1 is planted to corn. The ASP2 was planted with winter camelina in the fall of 2023 and was double cropped with soybean after winter camelina harvest in June 2024. Data collected at all on-farm LTAR sites includes micrometeorological data, soil samples, apparent electrical conductivity, combine yield, RGB multispectral sUAS (drone) images, and continuous phenocam images. Additionally, the National Agricultural Library (NAL) received phenocam data, which are displayed graphically and available to the public. The ASP1 and ASP2 fields were the focus of the Morris unit's annual field day. The farmer collaborator and other collaborators with University of Minnesota Forever Green Initiative in partnership with Cargill were participants.
The on-farm LTAR research under Objective 2 continues to be augmented with external funding, which continues collaboration with university scientists in Nebraska, Wisconsin, and South Dakota; ARS researchers in Iowa and Nebraska; and private partners. The additional measurements on ASP1 for nitrous oxide and methane using Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS), automated closed vented chambers, and plant sampling to assess crop development and provides a finer resolution of the soil properties continues due to this funding. Complementary work on greenhouse gas emissions as impacted by dual function oil seed crops is reported in the NP305 (5060-21220-007-000D) annual report.
Objective 3: Progress was made on research efforts in the Long-Term Tillage Study (TS). The 2024 growing season marks the second full year of lysimeter and infiltration/water runoff data collection. Analyses were completed for nutrients in lysimeter and runoff water from the preceding year, which were delayed due to renovations that affected access to in-house analytical lab facilities. Additional analyses to evaluate soil respiration using a 24-hr burst method were delayed at the beginning of the 2024 growing season due to substantially greater spring rainfall that prevented access to the plots without undue damage from smearing or compaction. However, respiration measurements of greenhouse gas emissions in collaboration with the in-house sister 305 project have proceeded. The targeted treatments, aspirational with diverse rotations including winter covers, and reduced tillage (no-till and strip tillage) have become prominent engagement tools with stakeholders and others and led to potential collaborations.
The efforts attributed to the long-term tillage study (TS) (Objective 1), the on-farm LTAR research (Objective 2), and the extension of treatments incorporating additional LTAR aspirational concepts within the TS (Objective 3) gained the Morris unit significant attention. To this end, the Morris unit is now a part of the newly established Northern Boundary Waters LTAR locations.
Accomplishments
1. Biodegradable hydromulches are an effective weed control in organically-managed strawberry. Polyethylene plastic mulches, widely used in organic production systems for weed suppression, are not biodegradable, therefore may contribute to plastic pollution. ARS researchers from Morris, Minnesota, in collaboration with North Dakota State University and Washington State University, investigated the effect of replacing non-biodegradable plastic mulches with biodegradable liquid-applied hydromulch (HM) treatments made from mixtures of paper pulp with either a guar gum or psyllium husk tackifier on weed control in organically-managed strawberry. In both North Dakota and Washington plastic mulch suppressed 100% of weeds. In Washington weed densities (average 65 plants m-2) did not differ among HM treatments, but in North Dakota guar gum-based mulches had lower weed densities (average 3 plants m-2) compared to the other treatments (average 11 plants m-2). Strawberry fruit yield did not differ among mulch treatments in Washington. However, fruit yield was up to 15 times greater in hydromulch treatments compared to plastic mulch in North Dakota. Results demonstrate mulches made with guar gum are a promising alternative to plastic mulch in organic strawberry systems based on ability to suppress weeds, enhance strawberry growth, and maintain yield. These results will benefit producers, researchers and others interested in improving weed management and environmental outcomes with use of biodegradable mulches.
Review Publications
Ruis, S., Johnson, J.M., Blanco-Canqui, H. 2022. Crop residue management and soil water. In: Blanco, H., Kumar, S., Anderson, A., editors. Soil Hydrology in a Changing Climate. Clayton South, VIC, Australia: CSIRO Publishing. p. 107-131.
Ahmad, W., Devetter, L., Mcfadden, D., Maupin, B., Bajwa, D., Durado, A., Weyers, S.L., Galinato, S.P., Weiss, B., Gramig, G. 2024. Hydromulches suppress weeds and maintain fruit production in organically managed strawberry systems. Frontiers in Agronomy. 6. Article 1375505. https://doi.org/10.3389/fagro.2024.1375505.
