Location: Soil Management Research
2022 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.
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 focused on the Farming Systems Study (FS) and Alternative Biomass Production Systems (ABP) projects. The FS study compares organic and conventional management with a four-year or two-year rotation, conventional or strip tillage, and fertilization or no-fertilization. The ABP compares traditional two-year corn soybean rotations to alternative biomass production of perennial grasses or sorghum/sudan grass, all under strip tillage. Specific progress for Objective 1A was made for the FS by completing analysis of particulate organic matter (POM) on archived samples from 2004, 2006, and 2007. Differences between tillage methods were more pronounced than differences between other treatment comparisons; whereby more organic carbon was found under strip-tillage than conventional tillage. Additionally, analyses on archived samples from ABP included permanganate oxidizable carbon (POxC) and POM. Made progress to compile yield data from 2006 to 2021 on all plots from the Tillage Systems Study (TSS), which in general, is a comparison of corn-soybean rotations under conventional tillage, no-tillage, or strip-tillage, which comprises all ABP treatments. Additionally, work continued on the long-term (20+ years) Carbon Crop study that includes comparisons among: 1) corn/soybean, 2) corn/soybean/wheat plus cover crops, 3) extended corn/soybean/wheat+alfalfa/alfalfa/alfalfa and 4) perennial grasses (big blue stem and switchgrass). This growing season marks 22 years of agronomic data collection. The fourth interval of soil sampling to 100-cm will occur after the growing season. Made progress on Objective 1B by compiling the new data on POM to be analyzed in the preliminary metric.
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 2022, BAU field is planted to corn. ASP1 is planted to soybean due to adverse moisture preventing corn planting. The ASP2 was originally scheduled to be planted to spring wheat; however, due to adverse planting conditions the producer may plant either soybean or winter wheat, the decision is pending. The need to modify rotations reflects the reality faced by producers as they adapt to unexpected weather conditions. 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. Progress made on Objective 2 was documented by Browning et al., “Monitoring agroecosystem production and phenology at a continental scale: A metric assessment framework,” published in Ecological Indicators (2021), which evaluated the utility of phenocam data. Additionally, the National Agricultural Library (NAL) received phenocam data, which are displayed graphically and available to the public.
The on-farm LTAR research under Objective 2 is augmented with external funding, which established a new collaboration with university scientists in Nebraska, Wisconsin, and South Dakota, ARS scientists in Iowa and Nebraska, and private partners. The external funding facilitated additional measurements on ASP1 for continuous measurement of nitrous oxide and methane using Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS), and automated closed vented chambers. The external funding includes additional plant sampling to assess crop development and provides a finer resolution of the soil properties. 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: In 2020, the TSS, located at the Swan Lake Research Farm, transitioned into an on-station plot-scale component of the LTAR croplands common experiment. The on-station study includes the Swan Lake Weather Station a part of the LTAR project and includes a phenocam taking images of plot-scale research of the Tillage/System/LTAR on-station component. Lysimeter installation is planned for summer of 2022 to monitor additional aspirational strategies, excessive spring rain and high soil moisture delayed progress. Objective 3 is augmented by an externally funded experiment, which is a multi-field/farm evaluation of two aspirational systems, a winter camelina following silage corn for winter cover, and a Kura clover employed as a perennial mulch in a silage corn – soybean rotation that are compared to best management practices (BMP) of corn-soybean. This experiment includes analysis of nitrates in runoff water and lysimeter soil water samples. In 2022, this supporting experiment entered the third summer of data collection. To date, data indicate that the Kura clover significantly reduced soil water nitrate over other treatments; however, Kura also compromised corn and soybean yields, often to the extent that production can only be taken off as forage. Nitrate in soil water under winter camelina was also reduced, but not significantly throughout the growing season compared to BMP.
Accomplishments
1. Forage radish and annual rye grass captured residual nitrogen but did not reduce nitrogen fertilizer needed by corn compared to no cover crop. Nitrogen, an essential nutrient for crops, can be an expensive fertilizer input for producers with undesirable consequences for water quality if it moves into surface or ground waters. In the northern Corn Belt, the adoption of cover crops after corn or soybean continues to be limited. However, when spring wheat is included in the rotation it affords an opportunity to establish cover crops after its harvest. ARS researchers in Morris, Minnesota, in a three-year study, evaluated the effect of annual ryegrass, a daikon type radish and no cover crop, planted after wheat harvest, combined with increasing nitrogen fertilization rates on corn grain yield the following year. Both cover crops scavenged residual soil nitrogen but neither cover crop treatment supported the hypothesis that corn yield could be maintained with less nitrogen fertilizer compared with no cover crop. In addition, the study also found that applying half the recommended rate of nitrogen had little impact on grain nitrogen content. This research suggestions that land managers might reduce nitrogen application rates without a loss of yield or grain quality and thereby reduce environmental risk and nitrogen fertilizer input costs.
2. Microalgae enhance soil fertility and stabilize soil structure. Microalgae such as cyanobacteria have potential to serve as both biofertilizers and soil structure enhancers, but further understanding of use and impacts are needed. ARS and University of Minnesota researchers in Morris, Minnesota, determined how soil inoculations with Anabaena cylindrica, a nitrogen-fixing cyanobacteria, influenced soil aggregate stability, erosion resistance, and nutrient delivery. Following soil inoculation with the algae, water stable soil aggregates increased, which reduced soil loss in surface runoff and potential nutrient loss through runoff or drainage. Plant available nitrogen (N) and phosphorus (P) were also provided through decomposition of algal biomass. These findings suggest agriculture would benefit from microalgae-based biofertilizers and can be used by other researchers and policy makers to further develop and promote microalgae as a biofertilizer.
3. A novel framework optimizes the selection of metrics needed for monitoring, modeling, and forecasting ecosystem productivity. Many metrics and sensors are available to agricultural agencies, managers, and individual producers to measure productivity. Yet, knowledge of which metrics and sensors to use and when is needed to support decision making. Capitalizing on the unprecedented opportunity provided by the Long-term Agroecosystem Research (LTAR) network, ARS scientists in Morris, Minnesota, and other locations documented differences in metrics for growing season length and productivity in diverse agroecosystems. They developed a novel “metric assessment framework” to optimize the selection of instruments used to monitor, model, and forecast ecosystem productivity. The framework serves as a new path forward to integrate the data streams available to producers and land managers for better monitoring and forecasting of primary production at short- and long-term time scales. Researchers, land managers, policy-makers, and industry leaders working at multiple scales of agroecosystem management will benefit from this analysis and framework designed to streamline research design and provide information on the timing of optimal production potential with shifts in growing season due to weather and changes in climate.
4. Tillage-induced degradation of soil properties might be mitigated by converting marginal or highly sloped land from crops into perennials. Land management choices, often made to achieve agronomic and economic outcomes, can impact a range of soil biological, chemical, hydrological, and physical properties. ARS scientists from Morris, Minnesota, and other locations in collaboration with University of Minnesota directly measured the rapid degradation of soil properties including loss of soil organic carbon and decreased hydrological function following a tillage disturbance to remnant prairie. A related study indicated that degradation of soil properties on higher sloped or marginal land would benefit from converting from crops back to perennial systems like pasture or conservation reserves. Collectively, these studies clearly demonstrated soil properties can be quickly altered even by a single tillage event when prairie is converted to row cropping. However, restoring soil stability and other properties with perennials can take 10 to >40 years. This work is important to scientists, conservationists, policy-makers and producers for determining environmental costs and benefits related to management decisions.
Review Publications
Alvarez, A.L., Weyers, S.L., Johnson, J.M., Gardner, R.D. 2021. Soil inoculations with Anabaena cylindrica improve aggregate stability and nutrient dynamics in an arable soil and exhibit potential for erosion control. Journal of Applied Phycology. 33:3041-3057. https://doi.org/10.1007/s10811-021-02526-9.
Browning, D.M., Russell, E.S., Ponce-Campos, G.E., Kaplan, N.E., Richardson, A.D., Seyednasrollah, B., Spiegal, S.A., Saliendra, N.Z., Alfieri, J.G., Baker, J.M., Bernacchi, C.J., Bestelmeyer, B.T., Bosch, D.D., Boughton, E.H., Boughton, R.K., Clark, P., Flerchinger, G.N., Gomez-Casanovas, N., Goslee, S.C., Haddad, N., Hoover, D.L., Jaradat, A.A., Mauritz, M., Miller, G.R., McCarty, G.W., Sadler, J., Saha, A., Scott, R.L., Suyker, A., Tweedie, C., Wood, J., Zhang, X., Taylor, S.D. 2021. Monitoring agroecosystem productivity and phenology at a national scale: A metric assessment framework. Ecological Indicators. 131. Article 108147. https://doi.org/10.1016/j.ecolind.2021.108147.
Johnson, J.M., Scott, D.A., Weyers, S.L. 2021. Radish and annual ryegrass alter corn yield response to nitrogen rate. Soil Science Society of America Journal. 85(6):2054-2066. https://doi.org/10.1002/saj2.20311.
Li, L., Jin, V.L., Kettler, T.A., Karlen, D.L., Nunes, M., Lehman, R.M., Johnson, J.M., Mikha, M.M. 2021. Decreased land use intensity improves surface soil quality on marginal lands. Agrosystems, Geosciences & Environment. 4(4). Article e20226. https://doi.org/10.1002/agg2.20226.
Mikha, M.M., Jin, V.L., Johnson, J.M., Lehman, R.M., Karlen, D.L., Jabro, J.D. 2021. Land management effects on wet aggregate stability and carbon content. Soil Science Society of America Journal. 85(6):2149-2168. https://doi.org/10.1002/saj2.20333.
Scott, D.A., Johnson, J.M., Gesch, R.W. 2022. Cover crop and nitrogen rate management practices influence corn NDVI and nitrogen content. Agronomy Journal. 114:2473-2483. https://doi.org/10.1002/agj2.21085.
Strock, J.S., Johnson, J.M., Tollefson, D., Ranaivoson, A. 2022. Rapid change in soil properties after converting grasslands to crop production. Agronomy Journal. 114(3):1642-1654. https://doi.org/10.1002/agj2.21045.
