Location: Soil Management Research
2020 Annual Report
Objectives
Objective 1: Evaluate conservation practices adapted for use in short-growing seasons to enhance soil quality, improve nutrient use efficiency and sustain agronomic productivity.
Objective 2: Integrate soil and crop management practices that enable sustainable, climate-resilient agriculture for the Upper Midwest.
Approach
Two objectives are being addressed using a temporally-stratified and multi-faceted approach to select, evaluate and initiate integrated conservation practices for regional suitability. Data from seven long-term studies are providing the foundation for evaluating individual and integrated practices using statistical modeling and management assessment indices. These studies were designed with several types of conservation practices including tillage, conversion of perennials, including perennial in extended rotations, addition of cover crops and impacts of variable stover harvest rates. Each experiment study was set out as a randomized complete block or as a split plot – with randomized complete block within the spilt. All have four replications of each treatment. These long-term studies have SOC and corn grain yield data in common; so those variables will be used if conversion to 1) conservation tillage; 2) perennial grasses; or 3) including a winter rye cover crop increase SOC and if returning all crop biomass increases SOC compared harvesting stover.
Soil quality assessment indices approach: Assessment one tests the hypothesis that soil quality assessment scores will be greater (indicting improved soil quality) following multiple years of deploying a conservation practice compared to business as usual. Assessment scores at two (or more) time points from existing datasets from the long term studies will be used to determine if soil quality appears to be aggrading, degrading or remaining the same over time. A second assessment will be made using data collected form a common future data set from studies that will have been in place at least 10 years compare treatments lacking conservation to treatments with one or more conservation practices deployed. Comparisons of management strategies will be made using a mixed model ANOVA procedure to assess soil scores among treatments.
The ability of annual rye grass or forage radish to improve nutrient use efficiency in corn is being addressed. The null-hypotheses for this experiment are that yield, and N use of corn grown following cover crops (annual rye grass or forage radish) will not differ from corn grown without a preceding cover crop, and that the nitrogen fertilizer requirements will be similar for corn following wheat with or without a cover crop. Treatments were arranged in a replicated, randomized complete block design, which was blocked by field location and replicated four times. Cover crop shoot and root biomass, crop yield and N uptake, and soil N levels will be measured. Statistical analyses will analyze linear and quadratic effects of N treatments. Using a mixed-model ANOVA, cover crop will be treated as a fixed effect, N-rates as a continuous variable, and replication (within a site year) and site-year as random effects.
Progress Report
We made progress in finalizing the evaluation of conservation practices from the long-term Farming Systems Experiment conducted from 2002-2010, a component of Goal 1.1. Produced a publication that contributed to a better understanding of management practice influence on nitrogen availability. This completed effort is further addressed in the Accomplishments section of this report.
Progress continues with another long-term study. We reincorporated the strip-tillage plots of the alternative biomass production system (ABP) conducted from 2008-2019 back into a long-term tillage experiment initiated in 1996. The tillage experiment continues as a comparison of no-tillage, strip-tillage and moldboard plow tillage in corn-soybean rotation systems. We established a new rotation within strip-till plots as a part of the Long-Term Agroecosystem Research (LTAR) for the Upper Mississippi River Basin. This newly added component is a soybean-wheat rotation that includes a winter cover crop, winter camelina. We retained the two-year rotation system for this added comparison but made the switch from corn to wheat to assist in the establishment of the winter camelina. The extremely wet soil conditions in the fall of 2019, caused a slight set-back in finalizing the ABP experiment preventing collection of the planned final full-experiment soil sampling event. The full soil sampling has been rescheduled tentatively for the fall of 2020. In addition, to account for any possible changes in those plots that transitioned into wheat, soil in those plots were sampled in the spring. Made substantial progress to compile data from 1996 through the ABP years to present into the Data Entry Template for the the Greenhouse gas Reduction through Agricultural Carbon Enhancement network and The Resilient Economic Agricultural Practices (GRACEnet/REAP) data base.
Progress continues on the carbon crop study, which is a long-term study established in 2000 to assess strategies for increasing soil carbon (C) sequestration in a field managed without tillage. A total of twelve different strategies are being assessed. These strategies include extended crop rotations including a perennial legume (alfalfa), three-year rotation (corn-soybean-wheat), two-year corn-soybean (C-S) rotation with a cover crop, and perennial grasses managed as a cellulosic biofuel. All agronomic samples collected in the fall of 2019 were processed and chemical analyses were conducted. In a related collaborative project, assessed changes in soil physical, chemical and hydraulic properties after the conversion of perennial grassland vegetation to annual row crop production and prepared a manuscript for submission.
The Biomass Residue Return study is a three-field study that was established in 2005. This long-term study is now in the eighth cycle of stover removal. Analyzed data analysis and substantially completed a manuscript assessing the relationship between water stable aggregates and the rate of stover return. Completed multi-year analysis of the change in soil organic carbon after six cycles of stover harvest. Collected and processed agronomic sampling for 2019 it is ready for statistical and graphical analyses.
Objective 1.2. Substantially completed manuscript preparation of a three-year study that evaluated the impact of two winter cover crops on nitrogen use in corn.
Objective 2. Significant progress has been made to understand soil and crop management practices that enable sustainable, climate-resilient agriculture for the Upper Midwest. Substantial progress is being made on data synthesis based on the Resilient Economic Agricultural Practices (REAP) cross location effort using soil carbon as an indicator of soil quality. Assembled an integrated data set and initiated on-going individual site and cross-set comparisons. Life-cycle analysis modelers, commodity groups, other researchers and policymakers are using data from these long-term, multi-location data to inform and guide decisions. One specific example where this research is being used is the development/review of the Renewable Fuels Standard. Gave presentation and guest lectures to stakeholders and collaborators.
LTAR: The Morris location is part of the Long-Term Agroecosystem Research (LTAR) within the Upper Mississippi River Basin (UMRB) project area. We maintain and collect data from two Eddy Covariance (EC) towers located on a farm cooperator site. Secured a third site in the fall of 2019. Equipped the new EC tower with same instrumentation as the original two towers. In 2020 all sites are in the corn phase of their respective locations. All locations are instrumented with phenocams. Collected additional data collected at the LTAR sites including micrometeorological data, soil samples, apparent electrical conductivity, combine yield, and RGB multispectral sUAS (drone) images. The Swan Lake Weather Station located at the Swan Lake Research Farm is part of the LTAR project and includes a phenocam taking images of plot-scale research. All phenocams are included in the National Phenocam Network. Two staff members are certified drone pilots. Weather data is automatically collected and transferred to the National Agricultural Library (NAL) in near-real time. Data sets are displayed graphically and made available to scientists across the nation on the NAL site.
A member of the Morris LTAR team trained and tested a neural network for LTAR field segmentation (corn, 2017) as a template for full segmentation of all years/crops in preparation for analysis and utilization of phenocam images. He developed and tested a classification network for the 30-min phenocam images during the growing season; performed dimensionality reduction and selected the most relevant subset (days and times within days during the growing season) that captured maximum diversity in the imagery set. Developed a database for the selected subset images based on their RGB signatures. Furthermore, he performed data mining of the EC files and compiled the 30-min readings for the growing season duration. Soil chemical analyses data collected from the same field, meteorological data (rainfall, temp, etc.) and EC data and imagery data is being used in a deep learning modeling to include regression, classification, prediction, etc. as a template for the multi-years analyses of LTAR in Morris.
Compiled soil and crop ionome data from a long-term cropping system experiment into a relational database. Analyses and multiple manuscripts are being prepared.
Accomplishments
1. Manage nitrogen (N) to reduce fertilizer usage and avoid loss. Nitrogen leaked from production systems has negative environmental and economic consequences. Therefore, development of crop production management strategies that sustain productivity while reducing fertilizer use and potential loss are needed to improve agricultural sustainability. ARS researchers in Morris, Minnesota, and Mandan, North Dakota, undertook a multi-year evaluation of N availability in strip-tilled, conventional and organic cropping systems with a four-year rotation of corn-soybean-wheat/alfalfa-alfalfa. Under conventional management, mineral-N fertilizer application to the wheat phase of the crop rotation was enough to maintain yields comparable to county averages; however, benefits of N-fixation from legumes in rotation was unclear. Under organic management, organic-N based fertilizer application in combination with legumes increased N availability in comparison to the conventional system. Scientists, land managers, and policy makers will benefit from this research when they need to develop management systems to improve nutrient-use efficiency.
2. Maintain continuous agricultural green cover for sustainability. Continuous green cover of agricultural landscapes improves sustainability. The Midwest region of the U.S. is a highly altered and intensively managed agricultural landscape where current practices raise numerous environmental concerns including soil degradation and impaired water quality. Insufficient soil cover for a significant portion of the year due to tillage and other factors is a primary cause for both concerns. To improve both soil and water resources, a regional, multidisciplinary team including researchers at USDA-ARS in Morris, Minnesota; Iowa State University; University of Minnesota; University of Wisconsin; and Kansas State University identified the environmental benefits of growing a cool season grass as a perennial soil cover between corn and soybean rows. Benefits include mitigation of soil and nutrient loss through erosion and leaching without compromising annual crop yields. The approach can revitalize ecosystem services once provided by native prairie landscapes throughout the region. The results will help researchers, land managers, and policy makers develop, support, and promote land management practices that provide both environmental and economic benefits.
Review Publications
Moore, K., Anex, R., Elobeid, A.E., Fei, S., Flora, C.B., Goggi, S., Jacobs, K., Jha, P., Kaleita, A.L., Karlen, D.L., Laird, D.A., Lenssen, A.W., Lubberstedt, T., Mcdaniel, M.D., Raman, D.R., Weyers, S.L. 2019. Regenerating agricultural landscapes with perennial groundcover for intensive crop production. Agronomy. 9(8):458. https://doi.org/10.3390/agronomy9080458.
Weyers, S.L., Archer, D.W., Johnson, J.M., Wilts, A.R. 2020. Management drives differences in nutrient dynamics in conventional and organic four-year crop rotation systems. Agronomy. 10:764. https://doi.org/10.3390/agronomy10060764.
