Location: Integrated Cropping Systems Research
2019 Annual Report
Objectives
Objective 1: Evaluate no-till production practices using diverse crop rotations and cover crops to manage soil in a holistic manner, improve farming efficiency (increase unit output/unit input) and sustain soil productivity.
Objective 2: Integrate soil and crop management practices for more sustainable agricultural systems applicable regionally and across a wide range of environmental conditions.
Approach
Healthy soil is fundamental to all plant and animal life, therefore, proper management of soil resources is essential. Recent concerns regarding global climate change as related to soil health and crop production are increasingly driving scientific research relevant to our customers. Producers in the northern Great Plains can utilize several management options that may improve soil health and ecosystem services including: no-till soil management, maintaining crop residues, diversifying crop rotations, and establishing cover crops. A region as variable as the northern Great Plains requires extensive research on how to best implement these and other beneficial management practices to improve sustainability.
To address these challenges, it is important to understand how soil and crop management practices directly and indirectly influence the soil-water-air environment. Our previous research identified management options that more efficiently utilize inputs (including water, nutrients, pesticides, labor, and fuel), showing that integration of multiple practices often produced more than additive benefits. In this project, we seek to integrate multiple management practices to result in resilient agricultural systems that are valid across a wide range of environmental conditions. We expect that this research will provide multiple systems services such as increased soil health, conservation of natural resources, improved crop yields and quality, and development of habitat for insects and wildlife, while maintaining or improving economic sustainability for producers.
Transfer of these integrated production systems to our customers through scientific publications, management guides, field day presentations, partnership with action agencies, and other mechanisms will lead to increased production efficiency, improved soil resource conservation, positive ecosystem services, and decreased environmental costs. The project seeks to (a) determine useful metrics for quantifying ecosystem services and environmental costs (particularly for soil biology and soil organic matter) and (b) quantify differences between systems to provide information about synergisms and trade-offs in the studied systems.
Progress Report
Research progress was made on all objectives and sub-objectives within the approved research project. Long-term research to evaluate the impact of crop diversity on crop yield, quality and soil properties was continued to meet research Objective 1. The second of the soil and plant microbiome analyses have been completed on long-term field plots featuring different crop rotations. The objectives of these studies are to determine the effect of prior crop on the plant microbiome of soybean and corn and relate changes in the microbiome with plant performance. Among preliminary findings, first year results showed that fungi inhabiting the corn rhizosphere are more responsive to the prior crop than bacteria and that soybean rhizosphere fungal communities with a winter wheat preceding crop were more diverse compared to corn as a preceding crop. Prospective biological measures of soil health (soil microbial biomass, soil extracellular enzyme activity, labile carbon, soil protein) were found to be affected by prior crop more than current crop in the 16-year field study of crop rotations. Further, the inclusion of oat or sunflower into four-year crop rotations notably increased the responses of these soil health measures compared to the two-year corn-soybean rotation. These biological data are being analyzed in the context of soil physical/chemical properties and crop performance. We completed the fifth and final year of field sample collection and analyses to examine the effect of cover cropping on soil moisture and temperature and their relationship with soil microbial activities. A suite of soil biological assays (soil microbial biomass, potentially-mineralizable nitrogen, soil extracellular enzyme activity, labile carbon, soil protein, and substrate-induced respiration) are being conducted in soil collected during multiple points in the 2018 growing season. Preliminary data has shown differing responses with the interseeded cover crops depending on the current cash crop phase (corn or soybean).
Research to evaluate the impact of incorporating cover crops into standing corn and soybeans was continued to meet research Objective 2. We continued into the fourth year of field studies to examine the effects of cover cropping on soil moisture and temperature and their relationship with soil microbial activities. A suite of soil biological assays (soil microbial biomass, potentially-mineralizable nitrogen, soil extracellular enzyme activity, labile carbon, soil protein, and substrate-induced respiration) are being completed on soils collected during the 2018 growing season. Soil moisture was continuously monitored at depths of 15, 30, 60, and 90 cm in plots with no cover crop and a cover crop mix. Seasonal changes in water storage were monitored in plots with no cover crop, a single species cover crop, and a mixed cover crop to estimate crop water use efficiency. Water samples were collected from 90 cm depth using porous suction cup lysimeters in plots with no cover crop and a cover crop mix to estimate leaching of nitrogen and phosphorus below the root zone. Preliminary data analysis is underway. Cash crop growth, yield and quality were measured for a fourth year. Soil samples will be collected following fall harvest to evaluate soil chemical properties and to make fertilizer recommendations for the 2020 growing season. Due to the inability to find a reliable seed source for winter camelina the relay crop portion of this experiment was not continued.
Accomplishments
1. Arbuscular mycorrhizal fungal responses to agricultural management practices. Arbuscular mycorrhizal (AM) fungi are considered to be a key group of soil organisms for soil health assessments and developing relationships between agricultural management practices, soil health, and ecosystem services. Thus, ensuring there is an effective and consistent measurement of AM fungi is important to stakeholders engaged in developing and implementing improved agricultural practices supported by reliable, science-backed indicators. These stakeholders include producers, non government organizations, USDA-Natural Resource Conservation Service, university and county extension agents, state professionals, researchers, and the general public. Unfortunately, it is not clear which measure of AM fungi is most useful for this purpose. In a three-year study of fall cover crop effects on corn production, researchers in Brookings, South Dakota, evaluated different measures of AM fungi, including propagule numbers, biomass (fatty acids), and activity (root colonization). We found that the numbers of AM fungi propagules capable of colonization of plant roots was an effective measure of AM fungal response to agricultural management. Biomass measured by the neutral lipid fraction AM fungi biomarker (C16:1cis11) was also responsive, while the same biomarker in the polar lipid fraction was not as useful. Corn root colonization did not respond to treatment. However, high levels of corn root colonization by AM fungi were negatively related to corn yield and nutrient uptake. Understanding the range of responses in measures of AM fungi and their relationships with crop performance will advance identification and characterization of improved cropping practices. Improved cropping practices will reduce input costs, protect air and water quality, and preserve soils that are the foundation for food security.
2. Measuring cumulative soil erosion since European settlement of the Midwestern U.S. Agricultural practices have substantially changed soil erosion rates in the Midwestern United States. Although much work has been devoted to understanding the changes in soil erosion rates with land cover change, the ability to quantify those changes at distinct locations on the landscape over long periods of time has been limited. Researchers in Brookings, South Dakota, and collaborators used a set of tracers and models to estimate presettlement and postsettlement erosion rates on a hillslope in west central Minnesota and showed that soil erosion has increased by approximately 1 to 2 orders of magnitude over a period of approximately 110 years. This research demonstrated the usefulness of the tracer and models to estimate natural and human-induced erosion. The large increase in estimated soil erosion rates after settlement are consistent with measured soil properties, especially differences in soil organic matter content across the landscape. Knowledge of historic and recent soil erosion rates is critical for understanding the spatial variability in agricultural land that affects the sustainability of crop production.
3. Offsetting the impact of crop residue removal with cover crops. Removing crop residue from the soil can have a negative impact on soil health, but there are value-added uses for crop residue that can bring additional economic benefits for producers. Because removing residue decreases soil carbon and reduces ecosystem services in the long-term, producers are adopting alternative management practices to protect their soil. Including cover crops has the potential to keep the soil protected from wind and water erosion, while improving soil chemical, biological and physical properties. Because of these advantages, cover crop acreage increased by 88.5% in South Dakota and by 79.1% throughout the United States between 2012 and 2017, as reported in the 2017 Census of Agriculture. Cover crops can easily be incorporated into production systems when cash crop residue is removed. ARS researchers in Brookings, South Dakota, and collaborators have shown when removing crop residue there is a negative impact on soil health, but these impacts can be reduced by incorporating cover crops into the production system. Specific benefits included improved soil water infiltration and storage through improved soil aggregation, decreased greenhouse gas flux, improved microbial activity and increased crop yield for the soybean phase when grown in a corn/soybean rotation. B Action and education agencies such as USDA-NRCS and university extension can use these research results to illustrate to producers the benefits of adopting cover crops and identifying the best opportunities to use them in their cropping systems.
Review Publications
Jelinski, N.A., Willenbring, J.K., Schumacher, T.E., Li, S., Lobb, D.A., Papiernik, S.K., Yoo, K. 2019. Meteoric Beryllium-10 as a tracer of cumulative erosion due to post-settlement land use in west-Central Minnesota, USA. Journal of Geophysical Research: Earth Surface. 124(874–901). https://doi.org/10.1029/2018JF004720.
Lehman, R.M., Osborne, S.L., Taheri, W.I., Buyer, J.S., Chim, B. 2019. Comparative measurements of arbuscular mycorrhizal fungal responses to agricultural management practices. Mycorrhiza. 29:227-235. https://doi.org/10.1007/s00572-019-00884-4.
Chalise, K.S., Singh, S., Wegner, B., Kumar, S., Gutierrez, J.P., Osborne, S.L., Nleya, T., Guzman, J., Rohila, J.S. 2018. Cover crops and returning residue impact on soil organic carbon, bulk density, penetration resistance, water retention, infiltration, and soybean yield. Agronomy Journal. 110:1-10.
Wegner, B.R., Subedi, K., Singh, S., Lai, L., Abagandura, G., Kumar, S., Osborne, S.L., Lehman, R.M., Jagadamma, S. 2018. Response of soil surface greenhouse gas fluxes to crop residue removal and cover crops under a corn-soybean rotation. Journal of Environmental Quality. 47:1146-1154.
Albert, P., Osborne, S.L., Mathew, F., Ali, S., Sieverding, H., Kumar, S., Nleya, T. 2019. Nitrogen requirements of Ethiopian mustard for biofuel feedstock in South Dakota. Agronomy Journal. 111:1304-1311.
