Expansion of agricultural production has irrevocably altered the earth’s landscape, impacting climate patterns, wildlife populations, soil health, water quality, and rural communities (USGS, 2007). Global meat and egg consumption are increasing: the USDA reports a 58% increase in global meat consumption over the past 20 years while egg production in the United States increased by 17% between 2008 and 2017. This demand is linked to a growing global population as well as changing human preferences and improved income levels. Coupled with meat and egg production is the production of manure, which can be managed as either a waste product or as a valuable resource to enhance crop production and build soil health. Here we propose an integrated study of novel management practices including manure management, tillage, and cover crops in corn-soybean cropping systems for long-term study of crop yield, soil health, and environmental resilience

The goal of this project is to assess the benefits of manure application and cover crops on soybean crop health and yield, water quality, and soil health. A new field site has been designed for extensive comparison of manure application timing, cover cropping strategies, and strip till management, with immediate and ongoing goals of evaluating crop health, yield, and environmental benefits. Our new field site will lead to multi-year study of environmental datasets. We will integrate our findings into educational materials and outreach activities led by Dr. Daniel Anderson and the Iowa Manure Management Action Group.

1) Active dissemination of information from this project through existing Extension programs and other scientific outlets. We will present information from these studies at ISU Research and Demonstration Farms Field Days, state and regional Extension meetings, and Iowa Learning Farms events as appropriate. Results from the first two years of research at the site (2021-2022) will be presented at the Soil and Water Conservation Society International Annual Conference (Denver, CO) and at the 2022 International Drainage Symposium (Des Moines, IA).
2) Development of educational and outreach materials to be used by Iowa Manure Management Action Group
3) Semi-annual and annual reports will be submitted to ISA.

Update:
This project is an extension of a long-term study evaluating the impacts of field management combining poultry manure, cover crops, and reduced tillage. In 2021, the Land mAnagement for improved Yield, Environmental Resilience, and Sustainability (LAiYERS) research site was established and the treatments were initiated with our first soybean crop planted after the subsurface drainage tiles and sampling wells were installed. The Iowa Egg Council funded initial plot establishment, site development, and continued research. Funding for the soybean crop analysis, water quality, and soil characteristics was provided by Iowa Soybean Association. The system considers manure application timing, cover crops, strip till, and nutrient application timing. This unique study will provide important information to farmers on how to best manage these systems for a range of environmental benefits, including soil health and resiliency to climate change. Ongoing evaluation of water quality and soil health is essential to measure and identify impacts of combined management practices.

Each of the nine system treatments are replicated in triplicate. The spring UAN treatments, with and without cover crops, serve as the experimental control. Supplemental nutrients, such as phosphorus, will be applied as field conditions indicate. An additional UAN treatment includes a split UAN application with spring side dress to address concerns with yield loss due to potential low nitrogen availability following cover crops. The manure application treatments allow for a side by side comparison of early winter and spring manure application with and without cover crops. We also include a balanced manure treatment with manure applied every 5 years (early winter application after soybeans in years 1 and 3). The plot and sampling well installation was completed in June 2021. Plumbing in the sampling wells and flow monitoring instrumentation has continued through 2022 as we prepare for electrical installation to the sampling wells. We anticipate electrical installation to be completed in November of 2022.

Manure or UAN fertilizer application timing impacted concentration results, with expected increases in concentrations after spring manure and UAN applications. In general, plots that were treated with manure in early winter 2021 (EW manure and balanced EW manure) had much higher early spring concentrations compared to the other treatments.
Fall soil analysis showed accumulation of phosphorus in the surface soil (0-6”) at plots that were treated with manure in early winter 2021 or spring 2022. All plots have M3-P levels indicating high or very high phosphorus. Total available nitrogen was relatively low in the fall for all treatments.

Progress Toward Project Metrics
KPI #1: Data on yield, soil and water quality. Measured annually by collection of environmental datasets.
Fall soil samples were collected on 11/3/22-11/4/22 and delivered to AgSource Laboratory in Ellsworth, IA for analysis. Select soil analysis results are presented in this report. Subsurface tile drainage water samples will be collected throughout the 2023 drainage season, with the first samples estimated to be collected in mid-April. Soybeans will be planted by May 15th, and soybean plant analysis will be conducted periodically throughout the growing season.
KPI #2: Improved understanding of manure integrated cropping systems and their impact on soybean yield and soil and water quality.
This metric will be achieved through continued progress on KPI #1. We are beginning the third year of research and data collection at the LAiYERS plots. The preliminary results indicate differences in water quality, specifically nitrate concentrations, in response to treatment. The lowest nitrate concentrations were measured Although the plots were planted to soybeans in 2021, these plots had yet to receive the first fertilizer-cover crop combination treatments. The 2023 soybean crops will be the first year to reflect treatment impacts.

View uploaded report

Update:
This is the third year of research at the LAiYERS (Land mAnagement for improved Yield, Environmental Resilience, and Sustainability) plots, evaluating the impact of poultry manure and cover crop impacts on water quality, soil health, and crop yield. The plots were established in 2021, with subsurface tiles and drainage sampling wells installed in spring, and soybeans planted (date) after installation was complete. The first treatments were initiated in the fall of 2021 with cover crops planted to the designated plots (Systems 1, 3, 4, 6, 8) and the early winter and balanced poultry manure treatments applied (Systems 4, 5, 8, 9). The spring fertilizer and poultry manure treatments were applied in 2022 for the corn year of the rotation.

Progress since our initial funding includes planting, harvest, and cover crop termination dates from 2021 through soybean harvest 2023. Additional field work in 2023 will include the early winter manure application for the 2024 corn year, scheduled to be applied on November 15th. The attached pdf provides a detailed timeline of activities.

Early analysis shows differences between treatments.
Differences in drainage water NOx-N concentrations were observed by treatment in 2023. The lowest measured concentrations were with the spring poultry manure treated plots, followed by the early winter and balanced manure plots. The highest concentrations were measured at the UAN plots, although these differences may not be statistically significant. All plots last received fertilizer treatment for the 2022 corn year (early winter 2021 or spring 2022). Data will be statistically analyzed and detailed in the final report.

Soybeans were harvested on October 9th. Preliminary analysis suggests a negative impact on crop yields with cover crops. The 2023 cover crop was terminated late (June 19) as part of an experimental design to evaluate the impact of cereal rye on weed suppression. While there was a measurable decrease in weed coverage with cover crops, a better balance in termination timing to achieve optimal yields is necessary.

Progress Toward Project Metrics
KPI #1: Data on yield, soil and water quality. Measured annually by collection of environmental datasets.
Environmental sample collection was completed throughout the 2023 season. Soybean plant samples, including leaf greenness and root nodules, were collected at various growth stages (V2, V5, R1) and cover crop samples were collected for biomass and tissue analysis at termination. Soil samples were collected with the soybean roots to a depth of 5-7” for nutrient analysis. Subsurface tile drainage water samples will be collected throughout the 2023 drainage season. The soybeans were planted on (date) and harvested on (date).
KPI #2: Improved understanding of manure integrated cropping systems and their impact on soybean yield and soil and water quality.
We have completed the third year of research and data collection at the LAiYERS plots. We continue to analyze the data to evaluate the treatment impacts on water quality, soil nutrient changes, and crop growth. The drainage data includes a year with fertilizer application (corn year; 2022) and no fertilizer application (soybean year; 2023), with distinct differences by treatment for each. Preliminary results suggest late termination of cover crops negatively impacted soybean yields.
This summer we were able to expand our outreach with the project to include a visiting elementary school teacher who was participating in the Research Experience for Teachers (RET) program at Iowa State University. With assistance, she evaluated and presented a poster highlighting the early results comparing the impact of cover crops on weed canopy, soybean plant greenness, and soybean root nodules. This data will be further evaluated to identify any system treatment effects on these characteristics.
Additional sample processing and data analysis will be completed over the next few months and included in the final report.

View uploaded report

View uploaded report 2

Updated May 17, 2024:
Project Title- Integrated agricultural systems to promote soil health and environmental resilience

This report summarizes the third year of research at the LAiYERS (Land mAnagement for improved Yield, Environmental Resilience, and Sustainability) plots, evaluating the impact of poultry manure and cover crop impacts on water quality, soil health, and crop yield. The 0.1 hectare (1/4 acre) plots were established in 2021 (see attached report), with subsurface tiles and drainage sampling wells installed in spring, and soybeans planted (June 30, 2021) after installation was complete. The first treatments were initiated in the fall of 2021 with cover crops planted to the designated plots (Systems 1, 3, 4, 6, 8) and the early winter and balanced poultry manure treatments applied (Systems 4, 5, 8, 9). The spring fertilizer and poultry manure treatments were applied in 2022 for the corn year of the rotation. The first manure treatments for the 2024 corn year were applied on November 15th, 2023 (early winter manure), and additional treatments will be applied in the spring of 2024.

Each of the nine system treatments are replicated in triplicate. The spring UAN treatments, with and without cover crops, serve as the experimental control. An additional UAN treatment includes a split UAN application with spring side dress to address concerns with yield loss due to potential low nitrogen availability following cover crops. Phosphorus and potassium are applied to the UAN treatment plots (Systems 1-3) for each corn year. The manure application treatments allow for a side by side comparison of early winter and spring manure application with and without cover
crops. We also include a balanced manure treatment with manure applied every 5 years (early winter application after soybeans in years 1 and 3). The plot and sampling well installation was
completed in June 2021.

An overview timeline (see attached report) highlights field activities, including planting, harvest, and cover crop termination dates from 2021 through soybean harvest in 2023. Manure and UAN were applied for the 2022 corn growing season (early winter 2021 and spring 2022), with no manure or UAN treatments applied for the 2023 soybean year. Soybeans plants were monitored throughout the 2023 growing season, with tissue samples collected at approximately the V5 growth stage on July 19th (no cover crop plots) and July 27th (cover crop plots). Additional field work in 2023 included the early winter manure application for the 2024 corn year on November 15th, strip tilling at all plots on Nov. 19th, and P&K applied to the UAN plots (Systems 1-3) on Nov. 19th.

Differences in subsurface drainage NOx-N between treatments were measured in 2023.
There were a few incorrectly planted (or not planted) cover crop plots in 2021/22 and 2022/23 as the AEA farm management team became familiar with the research site. For the purpose of this report we have included the actual applied treatments in the water quality data analysis discussion to improve the robustness of data observed. For example, plot 11 is assigned as a system 1 (UAN with cover crop), but planting of cereal rye was missed in the fall of 2021 and 2022. Therefore, the plot was treated in 2021/22 and 2022/23 as a system 2 plot (UAN with no cover crop) for this report instead of the plot’s assigned system 1. We accompanied the farm staff in the field for cover crop planting in the fall of 2023, and all plots were planted as assigned.

The drainage season average subsurface drainage water NOx-N (nitrate-N + nitrite-N) concentrations were similar for all treatments in 2022. Differences in drainage water NOx-N concentrations were observed by treatment in 2023. The lowest measured concentrations were with the spring poultry manure treated plots, followed by the early winter and balanced manure plots. The highest concentrations were measured at the UAN plots, although these differences may not be statistically significant. All plots last received manure or fertilizer treatment for the 2022 corn year (early winter 2021 or spring 2022). There was no manure or UAN applied for the 2023 soybean year. Additional years of drainage sampling and analysis are needed to identify trends in NOx-N concentrations with treatment.

Cover crops suppressed weeds but negatively impacted soybean yields.

Cereal rye was drilled in 18 cm rows on Nov. 3rd, 2022. In 2023, soybeans were “planted green” into the standing cover crop on May 22nd. Field work was delayed, and the cover crop was terminated approximately 4-weeks after planting on June 19th. Cover crop above ground plant samples were collected and analyzed for biomass and nutrient contents. At each plot, duplicate samples were collected from 0.8 m2 quadrats. The quadrats were gently tossed into the cover crop to randomize sample collection, a photo was taken to document the cover crop canopy coverage, and all of the rye within the quadrat was cut at the ground and gathered in a plastic container to be weighed. After recording the weight, approximately 500 g of plant material was subsampled following AgSource recommended procedures and placed in a paper bag to submit for analysis. The cover crop analysis results showed high C:N ratios, indicating potential N depletion or tie up in the plots. The early cover crop biomass and tissue analysis data does not indicate a treatment effect, with relatively similar results for all plots. A longer term data set is needed to evaluate the impact of treatment on cover crop growth. The average biomass (dry) was 4.25 tons/acre, with a range of 3.14-5.46 tons/acre collected dry biomass. The average C:N ratio for all treatments was 62:1, with a range of 45:1 – 75:1.

Lori Kriz, a participant in the RET program (Research Experience for Teachers) monitored soybean plants during the summer. She documented plant greenness, canopy coverage, weed growth, and soybean root nodules at various growth stages. Her results were presented at poster session at the end of the program.

Crop (soybeans and cover crop) and weed canopy coverage were measured with the Canopeo app, a photo processing app that estimates the percentage of plant canopy in the field. Figure 4 gives an example of the Canopeo app canopy coverage results. Living vegetation is processed to white/blank space and the open soil surface is processed to black. The percentage of area covered in white is the canopy coverage. Total canopy was photographed, then all vegetation (weeds or rye) were removed to document the soybean canopy. Weeds were almost completely suppressed in the rye plots, and did not contribute to the total canopy in those plots.

The no cover crop plots had heavy weed coverage at the time of sampling, with the majority of the weeds identified as water hemp. The cover crop was effective at weed control, with relatively few weed seedlings identified in the cover crop plots.

While there was virtually complete weed control in the cover crop plots when evaluated during the above ground biomass sampling, there was also an impact on soybean plant growth. Soybean plants were monitored throughout the growing season, with observations recorded and samples collected at various growth stages. The height and density of the cover crops shaded the growing soybeans, with notably delayed growth stages of soybeans in the cover cropped plots compared to the no cover crop plots.

Differences in soybean nodulation were observed in cover crop vs no cover crop plots at V5 growth stage (see attached report). Soybean plants were carefully dug from each plot to collect intact root systems at the V2 and V5 stages to evaluate root nodule size and quantity (fig. 6). The tops of the plants were removed at about 2” above ground to reduce the size of sample stored in a cooler with ice in the field. The samples were transported to the Water Quality Research Lab (WQRL) and stored at 4°C until they could be processed. The root portion of the plants were gently rinsed, and the root nodules were carefully removed from the roots and dissected to observe the color of the nodules. Pink nodules indicate active nitrogen fixation. There was very little difference observed in the number of nodules counted at the V2 stage between the cover crop and no cover crop plots. At the V5 stage, more nodules were counted from the cover crop plots compared to the cover crop plots.

During the growing season, above ground soybean plant (leaf) samples were collected at approximately V5 growth stage on July 21 (no cover crop plots) and July 28 (cover crop plots). Leaf samples were collected following AgSource’s recommended sampling procedure for soybean tissue (leaf) analysis. The first fully developed trifoliate leaf from the top of each plant was collected, sampling 20 plants at each plot. Samples were transported immediately to AgSource for tissue analysis (N, P, and micronutrients). Soybean yields and select tissue analysis results are highlighted in table 1. The soybean tissue analysis indicated optimum availability of key nutrients, so nutrient tie up was not the driver of lower yields.

The soybean yields were highly variable between plots, but there was a measured decrease in average yields overall with cover crops when comparing the cover crop vs no cover crop yields for each N-source/timing treatment component. The late termination of the cover crops visibly impacted the soybean plant growth during early emergence and into the flowering stages. The robust cover crop was shading the soybean plants and competing for available moisture. While there was a measurable decrease in weed coverage with cover crops, a better balance in termination timing to achieve optimal yields is necessary.

Progress Toward Project Metrics
KPI #1: Data on yield, soil and water quality. Measured annually by collection of environmental datasets.

Environmental sample collection was completed throughout the 2023 season. Soybean plant samples, including leaf greenness and root nodules, were collected at various growth stages (V2, V5, R1) and cover crop samples were collected for biomass and tissue analysis at termination. These results were presented at the RET (Research Experience for Teachers) Showcase on July 25th. Soil samples were collected with the soybean roots to a depth of 5-7” for nutrient analysis. Subsurface tile drainage water samples will be collected throughout the 2023 drainage season.

KPI #2: Improved understanding of manure integrated cropping systems and their impact on soybean yield and soil and water quality.

We have completed the third year of research and data collection at the LAiYERS plots. The transition year (2021) involved intensive soil sample collection to document the background/starting conditions of the plots. The drainage data includes a year with fertilizer application (corn year; 2022) and no fertilizer application (soybean year; 2023), with distinct differences by treatment in 2023. Soybean plants were monitored at various growth stages throughout the season, and results suggest that late termination of cover crops negatively impacted soybean plant growth and yields. Soybean tissue analysis did not indicate nutrient deficiency, suggesting competition with cover crops for moisture and sunlight negatively impacted yields.
We were able to expand our outreach with the project to include a visiting elementary school teacher who was participating in the Research Experience for Teachers (RET) program at Iowa State University. With assistance, she evaluated and presented a poster highlighting the early results comparing the impact of cover crops on weed canopy, soybean plant greenness, and soybean root nodules.

View uploaded report

Final Project Results (layman's terms for all audiences)
Iowa State University has partnered with Iowa Soybean and Iowa Egg Council to explore
integrated agricultural systems to promote soil health and environmental resilience. Additional projects have been funded by the Egg Industry Center and Soil Tech to explore and document the dynamics involved in nutrient mineralization and the potential greenhouse gas potential. This is a unique, long-term study that included the establishment of new field plots in 2021, that are now established and producing useful data.

The field site includes 27 plots with the following treatments:
1. Cover crop with spring UAN
2. No cover crop with spring UAN
3. Cover crop with split UAN with 75 lbs N/acre spring applied and 75 lbs N/acre as sidedress
4. Cover crop with early winter manure
5. No cover crop with early winter manure
6. Cover crop with spring manure
7. No cover crop with spring manure
8. Cover crop with balanced early winter manure and spring UAN
9. No cover crop with balanced early winter manure and spring UAN

All plots are managed using strip till. The first manure and UAN treatments were applied for the 2022 corn year, with the first year of treatment effects monitored in 2022. Cover crop termination timing was managed in 2023 to look at the impact of cover crops on weed suppression. While there was a measurable decrease in weed coverage with cover crops, a better balance in termination timing to achieve optimal soybean plant growth and yields is necessary. Soybean plant growth was noticeably delayed in the cover crop plots, and the average soybean yields were also lower with cover crops. Moving forward, this study will provide practical guidance to farmers interested in maximizing yield, resiliency to varying climatic conditions, and protecting downstream water quality.

Additional Funded Projects
Quantifying soil nitrogen dynamics in manured fields. Iowa Nutrient Research Center. S. Archontoulis, M. McDaniel, P. Kyveryga, S. Nelson. $171,200. 2021 - 2023
Manure management for sustainable egg production and environmental resilience. Iowa Egg Industry Center. S. McMillan, M. Soupir, D. Andersen, S. Hall. $84,990. 7/1/23 – 6/30/25.
Sensor integration to demonstrate benefits of regenerative agriculture on soil health. Soil Tech. S. McMillan, D. Andersen, M. Soupir, C. Gomes, N. Hoover. $50,000. 1/1/24 – 12/31/24.
Poultry manure management to promote soil health and environmental resilience. Iowa Egg Council. M. Soupir, D Anderson, N. Hoover. $69,540. 1/1/24-12/31/24.
Presentations
Manure Applicator Certification Program- Spring vs. Fall applied poultry manure video segment (recorded Sept.7th for 2024 training season)
Tours
IEC field day/site visit- November 15, 2023
Video for virtual tour- https://vimeo.com/891501928/772f6544c3?share=copy
Posters
Lori Kriz (RET participant), N. Hoover, M. Soupir. Assessing the Impact of Cover Crops on Soybean Plant Nodules, Weed Canopy, and Greenness. Poster presented at the conclusion of the RET program on 7/25/23.
Hoover, N.L., M. Soupir, D. Anderson, S.W. Potter, R.S. Kanwar. 2022. Land Management for Improved Yields, Environmental Resilience, and Sustainability. Poster presentation at the ASABE International Drainage Symposium, Des Moines, IA. 8/30/22 to 9/2/22.

The long-term outcome of this study would be to inform manure management and cover cropping management to optimize crop yield and environmental benefits and will directly benefit soybean farmers by providing strategies that reduce risk through yield stability and potentially yield increase. As soon as we have sufficient data from the site, we will be able to provide practical management recommendations to farmers and tie these best practices to economic outcomes as we have in past efforts. Further, these efforts will lead to fewer environmental impacts through less impaired waters, protected public health, and more sustainable agricultural systems. This information will be important for producers who are making management decisions and for state agencies that have responsibility for water quality. Producers will have valuable information to help guide management options while policy makers will have new information on manure management as part of watershed management plans.