Location: Soil Management Research
2023 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: Efforts focused on the Long-Term Tillage Study (TS) and the Alternative Biomass Production Systems (ABP) project set within the TS. The TS, established in 1997, is a long-term comparison of three main tillage types: moldboard plow, strip tillage and no-tillage. The ABP is set within the strip tillage plots of TS and 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 by compiling over 20 years of corn and soybean yield data. Differences in yields between tillage methods were apparent, whereby in some years, yields tended to be greater under the more intensive moldboard tillage for both crops. The data also revealed a slight decline in yields over time. In some years this could be attributed to drought, but also late planting, and potential issues with other pressures such as competition from weeds.
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. Information from the EC towers was included in a multi-location paper (Menefee et al., 2022, Log 394422). 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 2023, BAU field is planted to soybean. ASP1 is planted to corn. The ASP2 was planted to winter wheat. 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 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 researchers 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: Progress was made on research efforts in the Long-Term Tillage Study (TS). The 2023 growing season marks the first full year of lysimeter and infiltration/water runoff data collection. Analyses of nutrients in lysimeter and runoff water from the preceding year 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 on dried and rewetted soil were performed in a subset of treatments, the moldboard plow corn-soybean rotation, and a spring wheat/winter camelina-soybean rotation. These respiration measurement bolster greenhouse gas emissions testing performed as a component of the in-house sister 305 project. Preliminary analyses indicate that soil respiration measures matched the carbon dioxide (CO2) emissions, confirming a microbiological rather than root, abiotic or other source of emissions.
Accomplishments
1. The use of cover crops can simultaneously increase soil organic carbon and corn yields. Cover crops are plant species grown following a cash crop to provide soil coverage to reduce erosion and likely increase soil organic carbon. ARS researchers in Morris, Minnesota, contributed to a meta-analysis of published literature that assessed effect of cover crops in corn systems to increase soil organic carbon (SOC). The results of the analyzed data suggest that the current cover crop/corn production systems are sequestering 5.5 million tons per year in the United States and have potential to sequester 175 million tons per year globally. Along with increasing the soil organic carbon (SOC) adopting cover crops into a production practice increased corn yields by 23%. Climate scientists and action agencies (e.g., NRCS) can use this integrated analysis to improve C footprint, carbon inventory estimates and validate the value of cover crops as climate smart practice.
2. Matching characteristics of biochars and soils can have a beneficial outcome on carbon and nutrient cycling. Biochars made from high temperature, low oxygen combustion of plant or waste materials may have environmental benefits when applied to the soil. However, clear-cut outcomes with their use do not exist. ARS researchers in Morris, Minnesota, in collaboration with the University of Georgia, conducted short-term laboratory incubations to evaluate prospects of carbon sequestration and nutrient delivery from addition of poultry litter-based or pine chip-based biochars to two widely distributed Georgia soils. The results established that applying these biochars have the potential to improve soil carbon content and nutrient cycling process, but improvements were soil dependent. Using a short-term laboratory incubation provided scientists and land managers insights for selecting biochars suitable to soil type, thus facilitating potential for customer-focused recommendations to achieve desired site-specific environmental benefits from biochar land application.
3. Cyanobacteria biofertilizers provide soil fertility and increase resilience to extreme weather. Cyanobacteria, which fix both carbon and nitrogen, can be a good source of nutrients for agricultural systems. Although biofertilizers, in many forms, are a growing industry, advancement of cyanobacteria as a biofertilizer has been limited by fundamental knowledge gaps including effects on different types of soil and agroecological regions. ARS researchers from Morris, Minnesota, along with the University of Minnesota studied the effects of cyanobacterial inoculation to a nutrient-rich arable soil from the US Upper Midwest on soluble nutrients and microbial dynamics when subjected to repeated high intensity rainfall simulations. Increased soluble nutrient availability with cyanobacterial inoculations was linked to improved microbial biomass and activity. Results demonstrated the potential of using cyanobacteria to improve soil fertility and resiliency of arable soil exposed to extreme weather conditions. This research is useful for researchers and land managers seeking to use renewable resources to enhance agricultural sustainability.
Review Publications
Alvarez, A.L., Weyers, S.L., Gardner, R.D. 2023. Insights into the effect of cyanobacterial inoculations on the microbial dynamics of an arable soil under simulated rain. Biology and Fertility of Soils. 59:103-116. https://doi.org/10.1007/s00374-022-01686-1.
Joshi, D.R., Sieverding, H.L., Xu, H., Kwon, H., Wang, M., Clay, S.A., Johnson, J.M., Thapa, R., Westhoff, S., Clay, D.E. 2023. A global meta-analysis of cover crop on soil carbon storage within a corn production system. Agronomy Journal. https://doi.org/10.1002/agj2.21340.
Menefee, D.S., Scott, R.L., Abraha, M., Alfieri, J.G., Baker, J.M., Browning, D.M., Chen, J., Gonet, J.M., Johnson, J.M., Miller, G.R., Nifong, R.L., Robertson, P., Russel, E.R., Saliendra, N.Z., Schreiner-Mcgraw, A.P., Suyker, A., Wagle, P., Wente, C.D., White Jr, P.M., Smith, D.R. 2022. Unraveling the effects of management and climate on carbon fluxes of U.S. croplands using the USDA Long-Term Agroecosystem (LTAR) network. Agricultural and Forest Meteorology. 326. Article 109154. https://doi.org/10.1016/j.agrformet.2022.109154.
Weyers, S.L., Das, K.C., Gaskin, J.W., Liesch, A.M. 2023. Pine chip and poultry litter derived biochars affect C and N dynamics in two Georgia, USA, Ultisols. Agronomy. 13(2). Article 531. https://doi.org/10.3390/agronomy13020531.
