Research Project: Combined Management Tactics for Resilient and Sustainable Crop Production

Location: Integrated Cropping Systems Research

2022 Annual Report

Objectives
Objective 1: Evaluate the interaction of crop diversification practices (crop rotation, cover cropping) in no-till production systems with crop performance and soil properties, focusing particularly on identifying key management factors (e.g., crop identity and sequencing) that drive differential soil biological responses associated with crop performance and resilience. Sub-objective 1.A: Evaluate temporal considerations for sampling dynamic soil biological properties and associating these soil biological properties with key management factors including crop rotation, crop sequencing, crop identity. Sub-objective 1.B: Identify key crop management factors driving differences in rhizosphere microbiomes that correlate with crop performance in a no-till production system with long-term rotational treatments (established in 2000). Evaluate differential bacterial and fungal taxa for their applicability as soil health indicators in other systems within different soil-climatic regions via collaborative research. Sub-objective 1.C: Using long-term, no-till diverse crop rotations as a base crop production system, determine the influence of adding cover crop treatments on cash crop performance and soil physical, chemical and biological properties as these effects manifest with duration of treatments (cover crop treatments added in 2016). Objective 2: Integrate research data acquired on crop rotation and cover cropping within no-till production systems to advance awareness of sustainable crop production systems that are applicable regionally through a better understanding of the direct and indirect impact of these management practices on soil, water, and air resources. Sub-objective 2.A: Investigate rotational diversification (including oat) effects on crop growth and yield, soil properties, and economics to better understand the temporal influences of these outcomes and the mechanisms by which they contribute to productivity and resilience (Cote and Darling, 2010) of the whole cropping system to comprehensively demonstrate the feasibility of these practices to potential adopting producers. Subobjective 2.B: Investigate biotic and abiotic agronomic, edaphic, and climatic factors that influence the production and grain quality of oat in cropping systems.

Approach
A large proportion of commodity crop production in the Midwest has shifted to monocultures and simplified crop rotations over the past decades, resulting in unsustainable degradation of soil, air, and water resources. Furthermore, crop production is increasingly being destabilized by more frequent occurrences of extreme weather events associated with climate change. Emerging evidence indicates management practices, such as crop diversity and cover cropping, increase soil health and provide resilience to crops from stresses including drought, flooding, pests, pathogens, and weeds. Resilient crop production systems are an essential tactic to stabilize food supplies for a growing population and reduce financial liabilities in the face of variable climates. However, the specific biological characteristics of resilient soils remain unknown and the essential drivers of beneficial soil microbiomes are ill-defined. This project will examine and quantify impacts of diversified crop production systems (crop rotation, cover cropping) on crop production, soil properties, and microbial communities under the regional conditions of our research site. These crop diversification tactics are overlaid on a no-till cropping system with reduced inorganic nutrient inputs and crop residue retention; this system has been in place for 20 years. We will test, develop, and demonstrate crop management practices that provide benefits in terms of crop productivity, soil health, water use and quality, and air quality when adopted at scale. Concurrent with delineating the outcomes for crop productivity and soils, this project will elucidate prospective soil biological mechanisms underlying crop rotation effects. Demonstration of the outcomes of crop rotational diversity and understanding the drivers for these outcomes together serve as the foundation for increased adoption of these practices. This research will be applicable under similar soil-climatic regions across the globe to serve agricultural stakeholders (producers, crop consultants, agribusinesses, extension personnel, etc.), policy makers, and the general public.

Progress Report
Sub-objective 1A. We continued a study to examine the interaction between the timing of soil sampling (spring or fall) and the effect of crop sequencing on soil biological activities and soil structure measures. Soil samples were collected in the spring of 2022 from field plots representing corn and soybean phases of five different crop rotations. The samples are currently being measured for short-term potentially mineralizable C and soil aggregate distributions. The first-year data demonstrated that soybean following corn produces poor soil structure and microbial activities. We are testing a hypothesis that these observations are based on the timing of soil sample collection. In preparation for an intensive temporal study of soil microbial activities in these same corn plots within differing crop rotations, temperature and water content sensors were researched, acquired, and installed. The sensors are now equilibrating. Biweekly sampling of these plots, activity measurements, and their correlation with temperature and moisture will commence following spring thaw in 2023. We also conducted year 1 sampling and DNA analyses to evaluate a novel approach that relies on colonization of sterile soil packets for monitoring crop rotational effects on soil microbiomes. Sequence data on the sentinels was acquired using the third-generation, handheld Minion sequencing platform. Data analyses have demonstrated differing colonization kinetics for bacteria compared to fungi. Our findings will influence sampling strategies to increase the ability to discriminate treatment effects on soil microbiomes and their influence on soil properties and crop performance. Sub-objective 1B. We initiated a study to disentangle the impact of the microbial soil legacies from crop rotation and crop sequencing. A plant-soil feedback field trial was established in the spring of 2022 in which six crops (corn, soybean, pea, spring wheat, oats, and sunflower) were planted. Soil and plant samples were collected at three developmental stages (seedling, flowering, and mature) of the six crops. DNA will be extracted from samples and sequenced using the Mi-seq platform. We will investigate the shift of rhizosphere microbiome over plant growth stages this year. Next year, the same 6 crops will be planted perpendicular across this year's six crops to provide the opportunity to examine the effect of preceding crop independent of the overall crop rotational complexity. Sub-objective 1.C. Long-term research plots to evaluate the impact of no-till diverse crop rotations as a base crop production system were continued. The experiments are designed to evaluate the influence of cover crop treatments on cash crop performance and on soil physical, chemical, and biological properties. Long-term studies are needed because these effects manifest with duration of treatments. An additional year of crop phenology and crop yield were determined; fall soil samples were collected and will be processed. Rhizosphere soil and root samples were collected during two growth stages (seedling and flowering) of corn and soybean phases from the two-year corn-soybean rotation with and without cover crops. The initial goal is to investigate the impact of cover crops on soil microbial communities of corn or soybean and to evaluate the effect of cover crops on crop performance. Bulk soils were collected from the same plots to determine the effect of adding cover crops on soil biochemical properties. We initiated greenhouse studies to investigate the effect of cover crops on soilborne phytopathogens. Bulk soil was collected in the spring of 2022 before planting; these samples represented corn and soybean phases of two-year corn-soybean rotation with and without cover crops. The soil is currently being used in greenhouse studies to evaluate whether cover cropping changes the performance of susceptible soybean varieties when infested with soilborne pathogens (Soybean Cyst Nematode or Fusarium root rot). Sub-objective 2.A. Research continued to investigate rotational diversification effects on crop growth and yield, soil properties, and economics to better understand the temporal influences of these outcomes and the mechanisms by which they contribute to productivity and sustainability of the whole cropping system. All long-term experiment data was evaluated for quality control and organized to ensure data is available for additional analysis. Data from the previous crop rotational cycle (2017-2022) was organized and a collaboration with an agricultural economist at South Dakota State University was established to evaluate the economic risk associated with diversified crop rotation. In-season soybean and pea biomass samples were collected at specific phenology growth stages to evaluate in-season nitrogen dynamics. Objective 2.B. Research continued on an experiment established in fiscal year 2021 with substantial input from stakeholders studying milling oat traits and management tactics to minimize biotic and abiotic stress when grown with forage legume cover crops. A full year of sensor, plant, and soil data was collected from experimental plots in year 1 and analyzed and a second year of data collection begun. Results were shared with stakeholders at customer focus groups, field days, and individual meetings. Initial results suggest that in drought years, milling oats can be grown in polyculture with a forage legume cover crop at no cost to oat production, manageability, or quality. Sensing data indicates greater light and moisture resource utilization by the cover crop system both in the fall and spring. In conjunction with researchers in Minneapolis, Minnesota, we found that a consumer pocket camera sensor is able to track cover crop growth and nitrogen content regardless of sensing conditions. The cover crop fixed economically meaningful nitrogen in aboveground biomass and suppressed weeds by 50% versus the standard fallow practice. Contemporary, short oat varieties appear compatible with this cropping system. A second year of data is currently being collected.

Accomplishments
1. Fall seeded cover crops improve soybean yields two years following incorporation. Producers have shown interest in including cover crops in their cropping system to improve soil health and crop yield. However, it has not become a common practice, partially due to the lack of specific research results applicable to their region. This research was conducted in a small grain-cover crop/corn/soybean crop rotation at three locations in South Dakota to evaluate the influence of fall-planted grass, legume and brassica cover crops on the performance of the subsequent corn and soybean crops under no-till conditions. ARS Researchers in Brookings, South Dakota, found that fall and spring cover crop growth varied each year with varying weather conditions. Cover crop treatments had little effect on plant-available soil phosphorus. However, soybean yields two years following cover crop treatments were higher (up to 14%) for all three site years with cover crops compared to no cover crop, with this difference significant in two of the three site-years. Immediate effects of cover crops on the following cash crop under no-till were variable and depended on both fall and spring cover crop biomass, which in turn were dependent on the amount and timing of precipitation and temperature patterns. Cover crops in no-till systems may produce more consistent, but possibly delayed, benefits by boosting yields of cash crops in subsequent years as cover crop residues decompose.

2. Crop rotation field experiment is an international resource. In 2000, ARS researchers in Brookings, South Dakota, established a replicated no-till field experiment comparing a two-year corn-soybean crop rotation with a set of four-year crop rotations containing corn and soybean. In 2008, two full crop rotations were completed which meant the treatments had been implemented long enough to confidently assess effects of crop rotational diversity. At our site, we found that crop rotational diversity increased yields, reduced greenhouse gas emissions, sequestered soil carbon, suppressed plant pathogens, and was economically favorable. In 2020, the rotation treatments have matured further, with five complete rotation cycles. Data from this field experiment is now part of national and international multilocation studies of crop rotational diversity led by government, university, and non-profit institutions. These multi-location studies have concluded across a range of soil and climatic conditions that diverse crop rotations produce higher yields that increase with time and also more stable yields in the face of adverse growing conditions. Samples and data from these field plots have been used in multilocation studies illustrating that diverse crop rotations increase soil C via modification of the soil microbial community, and that increased soil carbon (C) is associated with increased plant available water and resistance to drought. These field plots have been used in multilocation studies that validate soil carbon and hydraulic indicators of soil health, with important implications for standardized testing procedures to verify the success of improved management practices. The extension of experimental conclusions across regions and crop production systems provides the foundation for decision making and policy formulation for institutions responsible for promoting sustainable food production systems around the globe.

Review Publications
Mooshammer, M., Grandy, S.A., Calderon, F., Culman, S., Deen, B., Drijber, R.A., Dunfield, K., Jin, V.L., Lehman, R.M., Osborne, S.L., Schmer, M.R., Bowles, T. 2022. Microbial feedbacks on soil organic matter dynamics underlying the legacy effect of diversified cropping systems . Soil Biology and Biochemistry. https://doi.org/10.1016/j.soilbio.2022.108584.
Veum, K.S., Acosta Martinez, V., Lehman, R.M., Li, C., Cano, A., Nunes, M.R. 2021. PLFA and EL-FAME indicators of microbial community composition. In: Karlen, D.L., Stott, D.E., Mikha, M.M., editors. Laboratory Methods for Soil Health Analysis, Volume 2. John Wiley and Sons, Inc. p. 251-288. https://doi.org/10.1002/9780891189831.ch12.
Manter, D.K., Moore, J.M., Lehman, R.M., Hamm, A.K. 2021. Microbial community composition, diversity, and function. In: Karlen, D.L., Stott, D.E., Mikha, M.M., editors. Laboratory Methods for Soil Health Analysis: Volume 2. Madison, WI: Soil Science Society of America. p. 289-323. https://doi.org/10.1002/9780891189831.ch13.
Chim, B., Osborne, S.L., Lehman, R.M., Schneider, S.K. 2021. Cover crop effects on cash crops in Northern Great Plains no-till systems are annually variable and possibly delayed. Communications in Soil Science and Plant Analysis. 53(2):153-169. https://doi.org/10.1080/00103624.2021.1984512.
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.
Schnecker, J., Meeder, D.B., Calderon, F., Cavigelli, M.A., Lehman, R.M., Grandy, A.S. 2021. Microbial activity responses to water stress in agricultural soils from simple and complex crop rotations. Soil. 7:547-561. https://doi.org/10.5194/soil-7-547-2021.
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.
Liptzin, D., Norris, C.E., Cappellazzi, S.B., Bean, G.M., Cope, M., Greub, K.L., Rieke, E.L., Tracy, P.W., Aberle, E., Ashworth, A.J., Baumhardt, R.L., Dell, C.J., Derner, J.D., Ducey, T.F., Novak, J.M., Dungan, R.S., Fortuna, A., Kautz, M.A., Kitchen, N.R., Leytem, A.B., Liebig, M.A., Moore Jr., P.A., Osborne, S.L., Owens, P.R., Sainju, U.M., Sherrod, L.A., Watts, D.B. 2022. An evaluation of carbon indicators of soil health in long-term agricultural experiments. Soil Biology and Biochemistry. 172. Article 108708. https://doi.org/10.1016/j.soilbio.2022.108708.
Reike, E., Cappellazzi, S.B., Cope, M., Liptzin, D., Bean, G.M., Greub, K.L., Norris, C.E., Tracy, P.W., Aberle, E., Ashworth, A.J., Baumhardt, R.L., Dell, C.J., Derner, J.D., Ducey, T.F., Fortuna, A., Kautz, M.A., Kitchen, N.R., Moore Jr., P.A., Osborne, S.L., Owens, P.R., Sainju, U.M., Sherrod, L.A., Watts, D.B., et al. 2022. Linking soil microbial community structure to potential carbon mineralization: A continental scale assessment of reduced tillage. Soil Biology and Biochemistry. 168. Article 108618. https://doi.org/10.1016/j.soilbio.2022.108618.
Bagnall, D.K., Morgan, C., Cope, M., Bean, G.M., Cappellazzi, S., Greub, K., Liptzin, D., Norris, C.E., Rieke, E.L., Tracy, P.W., Ashworth, A.J., Baumhardt, R.L., Dell, C.J., Derner, J.D., Ducey, T.F., Fortuna, A., Kautz, M.A., Kitchen, N.R., Moore Jr., P.A., Osborne, S.L., Owens, P.R., Sainju, U.M., Sherrod, L.A., Watts, D.B., et al. 2022. Carbon-sensitive pedotransfer functions for plant available water. Soil Science Society of America Journal. 86(3):612-629. https://doi.org/10.1002/saj2.20395.
Bagnall, D.K., Morgan, C., Bean, G.M., Liptzin, D., Cappellazzi, S., Cope, M., Greub, K.L., Norris, C.E., Rieke, E.L., Tracy, P.W., Ashworth, A.J., Baumhardt, R.L., Dell, C.J., Derner, J.D., Ducey, T.F., Fortuna, A., Kautz, M.A., Kitchen, N.R., Leytem, A.B., Liebig, M.A., Moore Jr, P.A., Osborne, S.L., Owens, P.R., Sainju, U.M., Sherrod, L.A., Watts, D.B. 2022. Selecting soil hydraulic properties as indicators of soil health: Measurement response to management and site characteristics. Soil Science Society of America Journal. 86(5):1206-1226. https://doi.org/10.1002/saj2.20428.