Research Project: Developing Aspirational Practices Through Improved Process Understanding to Protect Soil and Air Resources and Increase Agricultural Productivity in the Upper Midwest U.S.

Location: Soil and Water Management Research

2022 Annual Report

Objectives
Objective 1. Evaluate and develop innovative cropping systems and management practices to increase the resiliency and decrease the environmental impacts of agricultural systems. a. Develop management practices that address the key impediments to adoption of kura clover living mulch systems for corn production. b. Quantify the agronomic and environmental performance of corn grown with and without the use of novel soil amendments in integrated management systems. Objective 2. Improve fundamental understanding and predictability of nitrogen and carbon transformation processes to improve crop nutrient use efficiency and reduce nutrient losses, especially through engineered solutions. a. Reveal chemical mechanisms of N and C transformations occurring with biochar amendments and develop guidance for agronomic use. b. Quantify fundamental N process rates following urea addition to soil with and without soil amendments and incorporate missing processes into a dynamic model.

Approach
This project will address key challenges facing corn producers in the upper Midwest U.S., which include the need for strategies that extend vegetative cover for longer periods and reduce reactive nitrogen losses to aquatic systems and greenhouse gas emissions. These challenges will be addressed through a combination of field, lab, and modeling-based studies structured around two main objectives and four integrated sub-objectives. Objective 1 will utilize field and laboratory studies to evaluate and develop innovative cropping systems and management practices to increase the resiliency and decrease the environmental impacts of agricultural systems. Sub-objective 1A will evaluate the feasibility of overseeding kura clover into an existing alfalfa stand to maintain forage productivity during the kura clover establishment period and determine if reduced intensity tillage can produce early corn growth similar to rotary zone tillage if combined with injected anhydrous ammonia as a nitrogen source. Sub-objective 1B will quantify the agronomic and environmental performance of corn grown with and without the use of novel soil amendments in integrated management systems. The overall aim of Objective 2 is to improve fundamental understanding and predictability of nitrogen and carbon transformation processes to improve crop nutrient use efficiency and reduce nutrient losses. Sub-objective 2A will use laboratory studies to reveal the chemical mechanisms of nitrogen and carbon transformations occurring with biochar amendments which will be used to develop guidance for the agronomic use of biochar. Sub-objective 2B will quantify fundamental nitrogen process rates following urea addition to soil with and without soil amendments and incorporate missing processes into a dynamic nitrogen cycling model. This research will increase our understanding of fundamental soil processes to allow improved prediction of agronomic and environmental outcomes and generate recommended practices for corn producers and policy makers that utilize innovative cover crops, row establishment systems and soil amendments to maintain productivity, increase climate resilience and soil carbon storage, and decrease environmental risks.

Progress Report
Hypothesis 1A(i): We seeded kura clover into a well-established alfalfa stand to evaluate interseeding as a new method to establish the clover as the basis for a living mulch production system. Above-ground plant biomass samples were subsequently collected from four locations prior to each alfalfa hay cutting. Samples were dried and biomass was sorted by plant type (alfalfa, kura clover, and weed fractions). No kura clover biomass has been found up to 2 years following seeding. We have concluded that interseeding kura clover into an alfalfa stand may not be an effective management practice to establish kura clover, and that this may have been due to allelopathy of the alfalfa that inhibited germination of the clover. Hypothesis 1A(ii): A field experiment was conducted in a kura clover living mulch (KCLM) system to assess how different combinations of tillage and nitrogen (N) fertilizer practices affect corn grain yield and clover biomass production and distribution. Specifically, we wanted to see if a less intensive tillage practice, shank strip tillage (ST), could produce adequate clover suppression and corn grain yields compared to our standard practice, rotary zone tillage (RZT). Corn was seeded into KCLM prepared using either RZT or ST and fertilized with either anhydrous ammonia or ammonium nitrate. Spatial and temporal distributions of aboveground clover biomass, total root biomass, and soil N, were sampled seven times during the growing season and end-of-season crop yields were quantified. Total root biomass samples were analyzed for their 13C isotope signature to determine the relative abundance of clover (C3) and maize (C4) roots. The results showed that ST resulted in adequate clover suppression and high grain yields regardless of fertilizer N source. We also observed elevated soil nitrate concentrations in the interrow zone likely resulting from mineralization of below- and above-ground clover biomass. This soil N was spatially separated from the majority of corn root biomass, since very few corn roots were found in the interrow zone. This implies that there was limited corn uptake of the soil N in the interrow zone. This observation may also explain another finding – greater nitrous oxide (N2O) emission from the interrow than from the row, due to the N being available for soil microbial transformation into N2O via nitrification and/or denitrification. Goal 1A: A review of primary literature was conducted to compile phenology data from kura clover studies with a focus on available data from the Upper Midwest characterizing typical kura clover growth. We have collected data from Minnesota and Wisconsin which will further be augmented by our continuing field-studies in Rosemount and Lamberton, MN. Ongoing efforts with these data include developing a database to keep track of current and newly acquired phenology data as well as basic available data on weather, soils, and management information to provide context for future application of these data for model development. Goal 1B: Several rounds of laboratory microcosm experiments have been completed with the goal of quantifying the effectiveness of a class of chemicals, procyanidins, for inhibiting denitrification and N2O production in fertilized soils. Studies have been completed using procyanidins obtained from multiple sources and applied to several soil types using a range of addition rates and application timings. Some of the results indicate a promising level of inhibition. Follow-up studies are planned to evaluate effectiveness at the mesocosm and/or field scale. A gas mixing system was designed and assembled that allows soil microcosms to be conducted under a wide range of atmospheric conditions from fully aerobic to completely anaerobic. Using this system, additional microcosm experiments have been established to quantify the effects of N fertilizer addition on oxygen (O2) uptake rates in incubating soils. Oxygen uptake kinetics have been incorporated into the 2SN model so that the experimental data can be compared to model simulations including effects of decreasing O2 availability on nitrification- and denitrification-driven N2O production. Hypothesis 1B: We are awaiting the complete results of ongoing lab experiments before determining the treatments to be applied in field experiments starting in 2023. In the meantime, we initiated a field experiment assessing the effects of row-spacing and N fertilizer addition on N2O emissions from a soybean crop. This will also achieve the dual purpose of improving soil health and fertility in a field with a long history of continuous corn production by rotating into soybeans. Goal 2A: Laboratory instrumentation have been acquired and are being configured for determining the production rate of nitric oxide (NO) and nitrogen dioxide (NO2) following liquid inorganic N solution additions to biochar. Customized R-scripts have been written to automate data analysis and graphical presentation. With the developed methodology, the system is sensitive to production rates as low as 2 ng N per min for both NO and NO2. Additionally, a laboratory instrument has been set-up to perform the gas analysis of 15N isotopes and corresponding isotopomers of N2O from a 120-mL injection volume. Modifications are underway to enable the direct sampling of soil and/or biochar incubations from 240 mL (8 oz) incubation containers. Method improvement continues for the isotope ratio mass spectrometer instrumentation to enhance sample repeatability as well as the ability to analyze various packing materials from denuder tubes, which is needed for 15N tracer studies. Isotopic standards have been acquired to improve calibration of the IRMS for solid samples (soil, plant materials, and sold sorbents) for 13C and 15N. Assessments for the production rate of NO and/or NO2 from biochar following nitrite solution addition have been started. Hypothesis 2B: Analytical instrumentation described above to quantify 15N isotopes are also supporting the abiotic N fixation experiments. The first round of microcosm experiments assessing N fixation rates has been started. Soils were amended with 15N-labelled urea and/or nitrite and allowed to incubate, followed by a series of extractions to determine the amount of N that was fixed to the soil matrix. These results are currently being analyzed.

Accomplishments
1. Projected changes in average monthly rainfall did not alter growing-season N2O emissions. Precipitation and soil moisture are key drivers of emissions of the important ozone-depleting and greenhouse gas nitrous oxide (N2O). However, it is not clear how soil N2O emissions will respond to future changes in rainfall. We used a set of six soil mesocosms (each containing 2.2 m3 of soil) housed in a climate-controlled greenhouse to compare N2O emissions under historical precipitation (HP) for the past 30 years versus future precipitation (FP) predicted by the Coupled Model Intercomparison Project Phase 5 (CMIP5) for the U.S. Upper Midwest. The CMIP5 model projects monthly precipitation changes of +20% for May, -10% for June through August, and +10% for September relative to HP. Over 4 simulated corn growing seasons, the FP treatment did not affect growing-season N2O emissions. This study shows that projected changes in monthly average precipitation may not affect soil N2O emissions. However, more work is needed to determine if changes in the intensity of individual rainfall events will affect N2O emissions. These results have implications for scientists and policy makers involved in the development of management practices to reduce agricultural greenhouse gas emissions under future climate scenarios, and the modeling of these emissions.

Review Publications
Miller, L., Griffis, T., Erickson, M., Turner, P., Deventer, M., Chen, Z., Yu, Z., Venterea, R.T., Baker, J.M., Frie, A. 2022. Response of nitrous oxide emissions to individual rain events and future changes in precipitation. Journal of Environmental Quality. 51(3):312-324. https://doi.org/10.1002/jeq2.20348.
Spokas, K.A., Bogner, J., Corcoran, M. 2021. Modeling landfill CH4 emissions: CALMIM international field validation, using CALMIM to simulate management strategies, current and future climate scenarios. Elementa: Science of the Anthropocene. 9(1). Article 00050. https://doi.org/10.1525/elementa.2020.00050.
Lentz, R.D., Ippolito, J.A., Spokas, K.A. 2022. Does turbulent-flow conditioning of irrigation water influence soil chemical processes: II. Long-term soil and crop study. Communications in Soil Science and Plant Analysis. 53(5):636-650. https://doi.org/10.1080/00103624.2021.2017963.
Ferrari, F., Thomazini, A., Pereira, A., Spokas, K.A., Schaefer, C. 2022. Potential greenhouse gases emissions by different plant communities in maritime Antarctica. Annals of the Brazilian Academy of Science. 94(4). https://doi.org/10.1590/0001-3765202220210602.
Hu, C., Griffis, T., Frie, A., Baker, J.M., Wood, J.D., Millet, D.B., Yu, Z., Yu, X., Czarnetzki, A.C. 2021. A multiyear constraint on ammonia emissions and deposition within the US Corn Belt. Geophysical Research Letters. 48(6). Article e2020GL090865. https://doi.org/10.1029/2020GL090865.
Gamble, J.D., Baker, J.M., Dalzell, B.J., Wente, C.D., Feyereisen, G.W. 2022. Ecohydrology of irrigated silage maize and alfalfa production systems in the Upper Midwest US. Agricultural Water Management. 267. Article 107612. https://doi.org/10.1016/j.agwat.2022.107612.
Goodrich, D.C., Bosch, D.D., Bryant, R.B., Cosh, M.H., Endale, D.M., Veith, T.L., Kleinman, P.J., Langendoen, E.J., McCarty, G.W., Pierson Jr., F.B., Schomberg, H.H., Smith, D.R., Starks, P.J., Strickland, T.C., Tsegaye, T.D., Awada, T., Swain, H., Derner, J.D., Bestelmeyer, B.T., Schmer, M.R., Baker, J.M., Carlson, B.R., Huggins, D.R., Archer, D.W., Armendariz, G.A. 2022. Long term agroecosystem research experimental watershed network. Hydrological Processes. 36(3). Article e14534. https://doi.org/10.1002/hyp.14534. [Corrigendum: Hydrological Processes: 2022, 36(6), Article e14609. https://doi.org/10.1002/hyp.14609.]
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.
Baker, J.M., Feyereisen, G.W., Albrecht, K.A., Gamble, J.D. 2022. A perennial living mulch substantially increases infiltration in row crop systems. Journal of Soil and Water Conservation. 77(2):212-220. https://doi.org/10.2489/jswc.2022.00080.
Ducey, T.F., Sigua, G.C., Novak, J.M., Ippolito, J.A., Spokas, K.A., Johnson, M.G. 2021. Microbial response to phytostabilization in mining impacted soils using maize in conjunction with biochar and compost. Microorganisms. 9(12), Article 2545. https://doi.org/10.3390/microorganisms9122545.
Feyereisen, G.W., Hay, C.H., Christianson, R.D., Helmers, M.J. 2022. Eating the metaphorical elephant: Meeting nitrogen reduction goals in Upper Mississippi River Basin states. Journal of the ASABE. 65(3):621-631. https://doi.org/10.13031/ja.14887.
Goebel, K.M., Davros, N.M., Andersen, D.E., Rice, P.J. 2022. Tallgrass prairie wildlife exposure to spray drift from commonly used soybean insecticides in Midwestern USA. Science of the Total Environment. 818. Article 151745. https://doi.org/10.1016/j.scitotenv.2021.151745.
Williams, M.R., Welikhe, P., Bos, J.H., King, K.W., Akland, M., Augustine, D.J., Baffaut, C., Beck, G., Bierer, A.M., Bosch, D.D., Boughton, E., Brandani, C., Brooks, E., Buda, A.R., Cavigelli, M.A., Faulkner, J., Feyereisen, G.W., Fortuna, A., Gamble, J.D., Hanrahan, B.R., Hussain, M., Kohmann, M., Kovar, J.L., Lee, B., Leytem, A.B., Liebig, M.A., Line, D., Macrae, M., Moorman, T.B., Moriasi, D.N., Nelson, N., Ortega-Pieck, A., Osmond, D., Pisani, O., Ragosta, J., Reba, M.L., Saha, A., Sanchez, J., Silveira, M., Smith, D.R., Spiegal, S.A., Swain, H., Unrine, J., Webb, P., White, K.E., Wilson, H., Witthaus, L.M. 2022. P-FLUX: A phosphorus budget dataset spanning diverse agricultural production systems in the United States and Canada. Journal of Environmental Quality. 51:451–461. https://doi.org/10.1002/jeq2.20351.