Location: Soil Management Research
Project Number: 5060-11610-004-000-D
Project Type: In-House Appropriated
Start Date: Nov 3, 2021
End Date: Nov 2, 2026
Objective:
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.
