Progress 03/15/17 to 12/31/21
Outputs
Target Audience:The target audience for this project is organic farmers and agricultural professionals and scientists working in organic agriculture. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?This project was the basis for training Miranda Sikora (Masters' student) in soil science and agroecology. Additionally, it trained several under graduate students. How have the results been disseminated to communities of interest?A fact sheet was developed from this work and is posted on the OGRAIN website. Additionally, recorded video presentations summarazing this work are available on the OGRAIN website. Regular research updates were presented both at farmer-focused events (OGRAIN Annual Conference and Summer Field Day), MOSES Conference) as well as the Tri-Societies professional meeting. See below for a list of outreach events. --2021, October 1 How much do microbial communities matter in agriculture? NWREC Lunch & Learn seminar, Mount Vernon, WA --2021, August 23 How much do microbial communities matter in agriculture? Crop & Soil Sciences department seminar, Pullman, WA --2021, February 23 Organic row crop management & the biology of soil health. The Growing Stronger: Collaborative Conference on Organic & Sustainable Farming, virtual conference. --2021, February 9, Soil microbial communities respond to management and affect crop growth in Midwest cropping systems, SoilCon: Washington Soil Health Week, virtual conference --Soil health and teachings from a field survey in Wisconsin. Northwest Wisconsin Graziers Annual Fall Conference, Shell Lake, WI --Understanding the biological components of healthy soils. Ograin Winter Conference, Madison, WI, presented with Richard Lankau --Causes and consequences of microbial community change in dairy land organic farming. Crop/Soil/Agronomy Science Societies of America Annual Meeting, San Antonio, TX --Causes and consequences of microbial community change in dairy land organic farming. Ecological Society of America, Louisville, KY What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Objective 1. Soil samples were collected from 124 fields of 16 certified organic grain farms in the southwest Driftless Region of Wisconsin. Besides SOM and TOC, soil health indicators sufficiently diverged (R2 < 0.60) highlighting that they provide unique information regarding soil health and the bioavailability of C and N. Main pools of C and N (SOM, TOC, and TN) were most affected by soil taxonomy, textural-related soil information, and indices regarding soil depletion or erodibility. Total organic C was the only indicator affected by soil water properties, but demonstrated the importance of soil moisture in C cycling. Biological indicators representing the bioavailability of C and N (POXC, minC, PMN, and ACE) were differentiated by fewer NRCS variables. However, several NRCS soil health indices captured differences in many biological indicators as well as the larger C and N pools. NRCS properties and indices that utilized antecedent SOM content in their evaluation had relationships with soil health indicators, especially SOM and TOC. While many inherent soil properties contribute to differences in soil heath, farm management practices can improve or weaken the biological health of soils under agricultural production. Legacy land use and cropping sequences that utilized perennial cover had higher SOM and TOC. Nitrogen-cycling indicators were more affected by cropping sequence, crop diversity, and tillage. Incubation methods utilizing microbial activity to measure soil processes were more affected by the recency of manure application and the physical state of the manure. Mineralizable C was highly affected by sampling time and requires standardization of a sampling window for soil health comparisons. The disparate response of indicators to management indicates differences in sensitivity between indicators as well as soil elemental cycles. Therefore, multiple shifts in management may be required to support both healthy C and N cycling in agricultural systems. These results provide first-indications of best management practices for biological soil health in organic grain systems. Overall, regression tree analysis produced trees for over half of the indicators. Perennial cover within rotation sequences was most important for determining TN while soil surface sealing potential was most important for determining SOM and TOC. The results of this portion of the work were included in the thesis of Miranda Sikora, masters student in the programs of soil science and agroecology. Objective 2. Data was collected at the Wisconsin Integrated Cropping System Trial in Arlington, WI. A masters student in Dr. Silva's lab collected carbon, nitrogen, and microbial data in 2016 & 2017, which was used to quantify the effects of tillage and cropping strategies on soil chemistry and biology. Dr. Potter analyzed this dataset which was recently published (Potter, T.S., Vereecke L., Silva, E.M., Lankau, R.A., Sanford, G.R, Ruark, M. (2022)Long-term management drives divergence in soil microbial biomass, richness, and composition among upper Midwest, USA cropping systems. Agriculture, Ecosystems & Environment. DOI: 10.1016/j.agee.2021.107718). Objective 3. Soil inoculum from 11 fields across 5 farms of different lengths of time under organic management were added to sterilized background soil in pots to expose each plant to a specific microbial community. Certified organic soybeans, corn, and rye were grown. Four nitrogen types were added (plus a control treatment) to determine how the different microbial communities mineralize nutrients and impact each crop species. The four types of nitrogen were solid cow manure, red clover, sorghum sudangrass, and urea for comparison as a control. To address our primary hypothesis that microbial community composition and/or diversity matters more for mobilizing N from recalcitrant N sources like sorghum sudangrass than labile N sources like clover and manure we used likelihood ratio tests to statistically determine whether the effect of soil inoculum on crops' biomass was significant when comparing linear mixed model results between a model that included inoculum and a model that did not. To use both crop species' data standardized crop biomass data within species and used residuals as our response variable in the hypothesis test. Table 1. Results of likelihood ratio tests. N LRT P sorghum 2.81 0.026 clover 2.36 0.036 manure 1.65 0.062 control 0.52 0.162 Microbial community composition affected crop biomass most strongly for sorghum sudangrass (highest C:N) followed by clover and manure. Urea is not included due to a near zero estimate for its variance component. We used additional linear regressions to statistically show that control pots that did not receive microbial community inoculum resulted in significantly lower crop biomass and leaf chlorophyll reflectance and that the there were no farm fields that produced all-star communities (that mobilized N well across N sources nor crop species). Additionally, we tested whether the variation in microbial communities across farm fields could be explained by differences in management practices. We again used linear models to test for home field advantage (i.e that microbial communities that experience higher rates of manure additions would be better at decomposing manure, for example). Taken together, the set of completed research projects is generally consistent with previous research showing that farming management practices like tillage and cover cropping do alter soil chemistry and microbial communities, but that these management effects are small relative to the many other factors that influence soils. Like other studies, we detected management effects in a long-term trial in which treatments were consistently applied for x years and conducted in the same location (controlling for climate and soil type), but these management effects were much harder to detect in our unstructured field survey despite our large sample size of 128 fields with similar soil types and climate. A key accomplishment of these projects is that in addition to connect farming practices to changes in labile soil C and N pools and microbial communities we were able to demonstrate that the small, but consistently observed changes in soils chemistry and communities can impact crops' growth. While it is presumed that management effects on soil microbial communities would impact important outcomes like crop performance, our greenhouse study is one of the first to test this assumption. And while we demonstrate that unique microbial communities from different organic and conventional farm fields can influence crop growth, the differences in the microbial communities could not be explained by differences in farming practices. This result implies that dairy producers in this region may not be able to intentionally choose management practices that foster specific microbial community compositions that can serve functions like mobilization of organic N for crops. This is also the first study to establish that organic farming does not shift microbial communities in a consistent way over time. This finding suggests that soil health improvements due to organic farming are not a result of or indicated by microbial taxonomic composition. Additionally, Dr. Potter developed code to automate custom reports for growers who participated in the study. This template has since been adapted by laboratories doing similar field studies in Colorado and Washington State.
Publications
- Type:
Journal Articles
Status:
Submitted
Year Published:
2021
Citation:
Teal S. Potter, L�a Vereecke, Richard A. Lankau, Gregg R. Sanford, Erin M. Silva, Matthew D. Ruark,
Long-term management drives divergence in soil microbial biomass, richness, and composition among upper Midwest, USA cropping systems,
Agriculture, Ecosystems & Environment, Volume 325, 2022, 107718, ISSN 0167-8809,
- Type:
Theses/Dissertations
Status:
Accepted
Year Published:
2020
Citation:
Sikora, M. INHERENT SOIL PROPERTIES, FARM MANAGEMENT, AND BIOLOGICAL SOIL HEALTH IN ORGANIC GRAIN SYSTEMS
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Progress 03/15/19 to 03/14/20
Outputs
Target Audience:The target audience is organic farmers, ag professionals, and scientists. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?A post-doctoral trainee, Teal Potter, has been working with the group since 2018. Potter has also been mentoring a sophomore undergraduate student on a year-long independent project using data from the greenhouse experiment. This student is participating in the Undergraduate Research Scholars program at the University of Wisconsin. Additionally, with department graduate assistantship support, the field study has also provided learning and research opportunities for a master's student in Matt Ruark's lab. How have the results been disseminated to communities of interest?Presentations summarizing progress of this work were given at various farmer-focused and professional society conferences, including the OGRAIN Annual Conference and the Tri-Societies professional conference. What do you plan to do during the next reporting period to accomplish the goals?We will continue to analyze data and write peer-reviewd publications.
Impacts
What was accomplished under these goals?
Objective 1- Field soil samples for addressing were subsampled and all proposed C and N pools were measured in Matt Ruark's lab. Teal Potter, the post-doc on the project has begun the lab work for sequencing of microbial populations. With IRB approval, Erin Silva's lab interviewed organic farmers during the winter of 2018-2020 to collect data on field and management histories from each of the sampling sites. Objective 2- Léa Vereecke managed the field trials and soil samples and crop yields were obtained from the 2018 and 2019 growing seasons. Objective 3- Potter conducted the proposed greenhouse experiment during fall of 2018 and 2019. Soil inoculum from 11 fields across 5 farms were added to sterilized background soil in pots to expose each plant to a specific microbial community. Certified organic soybeans, corn, and rye were grown. Four nitrogen types were added (plus a control treatment) to determine how the different microbial communities mineralize nutrients and impact each crop species. The four types of nitrogen were solid cow manure, red clover, sorghum sudangrass, and urea for comparison. Approximately 70% of the data from the greenhouse experiment are ready for analysis. Data will be analyzed, and a manuscript will be drafted this spring and summer by Potter.
Publications
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Progress 03/15/18 to 03/14/19
Outputs
Target Audience:Target audiences include: organic grain and dairy farmers, researchers, and agricultural professionals. Changes/Problems:No major changes to report. A no-cost extension is requested in order to continue with data analysis and publications. What opportunities for training and professional development has the project provided?A post-doctoral trainee, Teal Potter, has been working with the group since 2018. Potter has also been mentoring a sophomore undergraduate student on a year-long independent project using data from the greenhouse experiment. This student is participating in the Undergraduate Research Scholars program at the University of Wisconsin. Additionally, with department graduate assistantship support, the field study has also provided learning and research opportunities for a master's student in Matt Ruark's lab. How have the results been disseminated to communities of interest?Rick Lankau and Teal Potter presented goals and preliminary results at the Ograin Winter Conference; coordinated by Erin Silva's lab on January 25th in Madison, WI. Research was also presented at the UW Organic Agriculture Field Days in 2018 and 2019. Additionally, research data was presented at the International Organic Long-term Systems Trial Conference in October 2019. What do you plan to do during the next reporting period to accomplish the goals?We have identified another set of unique fields to collect additional soil and field data for addressing objective 1. We plan to double our sample size in order to capture sufficient variation in our main variables of interest, namely: how long farms have been under organic management, soil types, and specific management practices such as tillage and crop rotations. Data from all experiments will be analyzed and manuscripts will be drafted this year.
Impacts
What was accomplished under these goals?
Objective 1- Field soil samples for addressing were subsampled and all proposed C and N pools were measured in Matt Ruark's lab. Teal Potter, the post-doc on the project has begun the lab work for sequencing of microbial populations. With IRB approval, Erin Silva's lab interviewed organic farmers during the winter of 2018-2020 to collect data on field and management histories from each of the sampling sites. Objective 2- Léa Vereecke managed the field trials and soil samples and crop yields were obtained from the 2018 and 2019 growing seasons. Objective 3- Potter conducted the proposed greenhouse experiment during fall of 2018 and 2019. Soil inoculum from 11 fields across 5 farms were added to sterilized background soil in pots to expose each plant to a specific microbial community. Certified organic soybeans, corn, and rye were grown. Four nitrogen types were added (plus a control treatment) to determine how the different microbial communities mineralize nutrients and impact each crop species. The four types of nitrogen were solid cow manure, red clover, sorghum sudangrass, and urea for comparison. Approximately 70% of the data from the greenhouse experiment are ready for analysis. Data will be analyzed, and a manuscript will be drafted this spring and summer by Potter.
Publications
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