We have designed and installed a new research site at Iowa State University’s Agricultural and Biosystems Engineering Research Farm, focused on poultry manure management for improved soybean yield, soil health and environmental resilience. The new site is located off of US-30 between the Central Iowa Expo in Boone and Iowa State University. The tile drainage system and sumps were installed in June 2021 and soybeans were planted as soon as the installation was complete. Soybeans were harvested in October 2021 and at the completion of harvest, rye cover crop was planted. Early winter manure application is planned for November 2021 and manure has already been delivered to the site by Farm Nutrients. Over the next year we will analyze yield, soil health, and water quality.

The goal of this project is to assess the benefits of manure application and cover crops on soybean yield, water quality, and soil health.

The outputs and deliverables of this project include the following:
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.
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.
4) Peer reviewed journal articles will continue to be developed from our currently funded project and these new efforts.

Update:
Year 1 Field Activities and Sample collection
Soybeans were planted late in the season.
The Research Farm was able to keep our original year 1 plan of planting soybeans, although soybeans were planted late in the season after the tile installation was complete. The soybeans were planted on June 30th, and were harvested on October 19th. The late season planting and dry weather conditions resulted in very low average yields of 19 bushels per acre compared to the county average of 63 bushels per acre in 2021.

Volunteer oat coverage was recorded.
Before installation of the center plot tile lines in the spring of 2021, the plots at field 40 were planted to oats so there would be vegetative coverage until the tiles were installed. After installation in mid-June, soybeans were planted. The soybeans were harvested on October 19th before soil sample collection from October 20th-22nd. There was considerable volunteer oat coverage in the plots noticeable after the soybeans were harvested. The vegetation coverage app, Canopeo, was used to document the volunteer oats coverage in each plot on November 4th and 5th. The average coverage per plot ranged from 6% to 16%, with an overall field average of 11%. The oats did not cover the plots evenly, but were stripped throughout the plots (attached file, fig. 2). The planned cover crop, winter rye, was planted on November 5th.

Soil Sample Collection
Plot level topsoil (0-12”) and Uhland cores (0-6”) were collected October 20-22 of 2021, and have been processed and analyzed similarly to the fall 2020 samples for detailed evaluation of soil health characteristics and nutrients (attached file, fig. 3). Additional soil analysis at the site includes a field level analysis of extreme deep core samples (8-9’ depth, divided into 1’ increments) (attached file, fig. 4).

Cereal rye was planted at the designated treatment plots.
Due to wet conditions in the field and the late soybean harvest, winter cereal rye was planted at the designated plots after soybean harvest on November 5th (attached file, fig. 5). We did not see emergence of the cereal rye in the fall. There has been some germination observed in early spring. The spring cereal rye coverage and biomass will be evaluated in late April, 2022.

The early winter poultry manure treatments were applied in 2021.
Poultry manure, which was donated by Farm Nutrients, was delivered and stockpiled for fall 2021 (early winter treatment) and spring 2022 (attached file, fig. 6).

The bulk manure was analyzed before application to estimate application rates. At the time of application, plot level samples will be collected from the manure wagon for analysis to calculate the achieved nutrient application rate at each plot.
The spring year 2 (2022) field activities will include UAN and poultry manure application at the designated plots (attached file, figs. 7 & 8). All plots will then be planted to corn in 2022.

Drainage samples and flow volume measurements will be collected at all plots throughout the drainage season while the plots are actively draining. These samples will be collected as grab samples with manual flow rate measurements at least once per week.

Progress Toward Project Metrics
Our group continues to make good progress toward KPI #1. Soil samples were collected in the fall of 2021 at each plot to provide detailed plot level baseline conditions. These samples have been processed for bulk density and texture analysis, aggregate size distribution, soil nutrient levels, and particulate organic matter nitrogen and phosphorus. Additional samples were collected on March 20th and 21st for weed seed bank analysis to establish the baseline densities. We are seeing signs of good drainage flow at the site, and will begin drainage sample collection in April.

KPI #2- improved understanding of manure integrated cropping systems and their impact on crop yield and water quality will be achieved through continued progress on KPI #1 and additional years of monitoring and data collection. The first comparative water quality samples from spring and fall manure application will be collected in year two (2022), which will reflect water quality impacts from the early winter 2021 spring manure application and the spring 2022 poultry manure application.

View uploaded report

Update:
Project Title- Integrated agricultural systems to promote soil health and environmental resilience

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 plots were established with funding from the Iowa Egg Council while the funding for the research 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. The following sections summarize our year two activities and results and the attached pdf includes references to figures and tables with detailed numerical results.

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.

Processing and analysis were completed to record the baseline soil conditions.
Processing and analysis were completed for soil samples (Uhland soil health cores and 0-12” topsoil cores) collected at each plot in the fall of 2021. Additional soil samples (0-6”) were collected on July 7th at all plots to evaluate available nutrients during the growing season after the first year of fertilizer treatments. The Uhland cores (3” diameter, 6” depth) were processed for aggregate stability and particle size and analyzed for particulate organic matter (POM) constituents.

Late spring topsoil (0-6”) samples were collected to assess the available nutrients for crop growth after the first year of applied fertilizer treatments. While differences were measured, a pattern of early treatment effects is not clear. Manure was applied to all manure plots in early winter 2021 or spring 2022 as designated (treatments 4-9), and UAN was applied to the UAN plots as a single spring application (treatments 1&2) or split application (treatment 3). The manured plots generally showed higher phosphorus levels (M3-P). The manured plots had somewhat higher available nitrogen with cover crops compared to no cover crops, while the UAN plots had somewhat lower available nitrogen measured with cover crop treatment

Year 2 Field Activities
Fertilizer and Manure Application
Year 2 marked the first year of poultry manure with the early winter application of December 2, 2021 and spring manure application on April 26, 2022. All plots were strip tilled, with phosphorus and potassium applied to the UAN plots on December 3, 2021. Chemical fertilizer (UAN) was applied on June 2nd at 150 lbs N/acre (spring UAN) and 75 lbs N/acre (split UAN). The split UAN plots had an additional 75 lbs N/acre applied on June 21st.

Manure samples were collected at the plot level and analyzed for nutrient and moisture content. Test results indicated lower than expected nutrient contents, and a substantial change in the available nutrients from the stockpiled manure between the early winter and spring sample collection and analysis.

While some loss in nutrient content is expected with storage and leaching, the large change observed from December 2021 and April 2022 was unexpected. Corn yield results should lend some insight into the validity of the sample analysis and indicate potential sampling or other errors. Funding from the Iowa Egg Council will be used to evaluate corn yield results.

Crop Yields
Year 1
Soybeans were planted and harvested in year 1 (2021) of the study. Soybeans were planted late in the season on June 30th and harvested on October 19th. Due to late planting and dry conditions in 2021, the resulting yields were very low. The measured yields ranged between 14bu/ac and 21 bu/ac, with an overall average of 19 bu/acre. The late season planting and dry weather conditions resulted in very low average yields compared to the county average of 63 bushels per acre in 2021.

Year 2- Corn
Corn was planted on June 2, 2022. Heavy rainfall in early June resulted in ponding and washout at some plots, which is expected to impact yield results. Field observations have been recorded and will be considered as evaluating the 2022 yield results. Harvest is anticipated the last week of October or first week of November. Funding from the Iowa Egg Council will be used to evaluate corn yield results.

Subsurface Drainage Sample Collection and Results
Due to continued dry conditions and no drainage flow during the first year of the study (2021), drainage sample collection and water analysis began in 2022. Tile drainage samples and flow rates were manually collected at each flowing plot outlet throughout the 2022 drainage season. Flow rates from each plot were measured using a stop watch and bucket method, with the flow from each outlet pipe collected in a 1 L plastic beaker and the elapsed time recorded to calculate flow rate. A 125 mL sample was then collected and transported to the Water Quality Research Lab (WQRL) for analysis of nitrate (NOx-N) and phosphorus (DRP) concentrations. The DRP analysis was highly variable due to sediment movement as the new tiles settle and clear (results not reported). The first year of results indicate early treatment effects, with lower nitrate in drainage with spring manure plus cover crops.

Progress Toward Project Metrics
KPI #1 Sample analysis was completed on the fall 2021 soil samples to provide baseline data and evaluate changes in soil characteristics over time. Additional soil samples were collected in late spring to measure available nutrients for crop growth and document potential early differences with treatment. The samples were processed and analyzed in the ISU-Water Quality Research Lab (WQRL) for bulk density, texture, and aggregate size distribution. Soil nutrient analysis was completed by AgSource Laboratories (Ellsworth, IA), and additional POM analysis was completed by Kansas State University.
KPI #2- Improved understanding of manure integrated cropping systems and their impact on crop yield and water quality will be achieved through continued progress on KPI #1 and additional years of monitoring and data collection. The tiles began flowing in 2022, and the first comparative water quality samples from spring and fall manure application were collected throughout the year two (2022) drainage season. The early results suggest the combined treatment of spring poultry manure and cover crops had the lowest measured nitrate concentrations with the first year of drainage.

Iowa State University has partnered with Iowa Soybean and Iowa Egg Council to explore integrated agricultural systems to promote soil health and environmental resilience. This is a unique, long-term study that included the establishment of new field plots in 2021. 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 100 lbs N/acre spring applied and 50 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 crop rotation at the site is corn-soybean, with soybeans planted in year 1 (2021) and corn planted in year 2 (2022). In the first-year, baseline soil health analysis was conducted and all plots were planted to soybeans. Because of dry conditions, initial yields were low and water samples were not collected (tiles did not flow). Tile flow was monitored in 2022, and drainage samples were collected and analyzed. Early results hint at the potential for combined management practices of spring manure and cover crops to positively impact water quality. Moving forward, this study will provide practical guidance to farmers interested in maximizing yield, resiliency to varying climatic conditions, and protecting downstream water quality.

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. 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.