Expansion and intensification of agricultural production systems have 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 tillage, and cover crops in corn-soybean cropping systems on crop yield, soil health, and environmental resilience.

The goal of this project is to assess the benefits of regenerative agricultural practices on soybean vigor and yield, water quality, and soil health. Our field site allows for extensive comparison of manure application timing, cover cropping strategies, and strip till management, with immediate and ongoing goals of evaluating crop vigor, yield, and environmental resilience. This site will lead to multi-year study of environmental datasets that provide practical information for farmers interested in regenerative farming strategies.

The experimental treatments include chemical fertilizer (UAN + MicroEssentials® SZ®) as a control, split UAN + N sidedress, manure applied in the spring or winter at the C-S recommended rate of 168 kg N per ha, and six-year management plan of of 200A poultry manure and UAN. Each treatment incorporates strip tillage before corn/no-till soybean and is managed with or without winter rye cover crops as a BMP. Each treatment is applied in triplicate to ensure reproducibility and statistical power.

We will integrate our findings into educational materials and outreach activities led by Dr. Daniel Anderson and the Manure Management Action Group. We will work to eliminate barriers to adopting regenerative agriculture practices through education and citizen science. We will disseminate outcomes through our industry partners and ISU extension; for example, in 2023 we recorded a talk used during Manure Applicator Training, which occurs annually at 70-locations in Iowa, reaching more than 5,000 individuals in the livestock industry.

The goal of this project is to assess the benefits of regenerative agricultural practices on soybean vigor and yield, water quality, and soil health.

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 were presented at the SWCS Annual Conference (Denver, CO) and at the 2022 International Drainage Symposium (Des Moines, IA).
2) Development of educational materials to be used by Manure Management Action Group
3) Semi-annual and annual reports will be submitted to ISA.

Update:
This report includes a brief overview of the end of year site activities and results from 2023, and the planned research activities and field work in the spring of 2024. The fourth year of research at the LAiYERS (Land mAnagement for improved Yield, Environmental Resilience, and Sustainability) plots begins in 2024. We will continue 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 soybeans planted in odd numbered years and corn planted in even numbered years. The treatments include chemical fertilizer or poultry manure applied at the agronomic recommended rate of 150 lbs N/acre, with or without cover crops.

Soybean Yields
The soybean crop was harvested on October 9th. Four passes from each plot were harvested, and yields were corrected to 13% moisture. As previously reported, the soybean yields were lower in the cover crop plots for all treatments due to the late termination of the cover crop (June 19th) as part of an experimental design to evaluate 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.

Poultry Manure and UAN Application
The early winter poultry manure was applied at an estimated 150 lbs available N/acre to the System 4 and 5 plots on November 15, 2023. This application rate includes an assumed 5% N loss at application and 60% N availability for the growing season. Manure samples were collected from the manure applicator at each plot and transported to AgSource laboratory in Ellsworth, Iowa the same day for nutrient analysis.
Poultry manure will be applied with the same loss and availability assumptions to the System 6 and 7 plots, and UAN will be applied at 150 lbs N/acre (100% availability assumed) to the System 1, 2, 8, and 9 plots in late April- early May. UAN will be applied to the System 3 plots at the same time at 75 lbs N/acre, with another 75lbs N/acre UAN applied in June as side-dress.

Cover Crops
Cover crops were broadcast into the standing soybean plants on September 22, 2023. There is good early spring growth visible in all of the cover crop treated plots. Above ground biomass samples will be collected before the rye is terminated approximately 10 days before corn planting, and below ground cover crop biomass samples will be collected approximately 2 days after termination.

Progress Toward Project Metrics
KPI #1: Data on yield, soil and water quality. Measured annually by collection of environmental datasets.
Environmental sample collection has begun for the 2024 season with the first subsurface drainage water samples collected from the tiles at the flowing plots on March 27th this year. Drainage water sample will continue weekly while the tiles are flowing, with planned event/storm sampling also.
Additional sampling will include cover crop tissue and biomass, late spring soil N, and fall deep core sore soil analysis. Cover crop samples will be collected this spring before corn is planted for above ground and below ground biomass analysis.

KPI #2: Improved understanding of manure integrated cropping systems and their impact on soybean yield and soil and water quality.
This will be the fourth year of sample collection and data analysis at the LAiYERS site. Results will be presented at the Soil and Water Conservation Society Annual Conference this July.
We continue to analyze the data to evaluate the treatment impacts on water quality, soil nutrient changes, and crop growth. The drainage data will include two drainage seasons with fertilizer application (corn years; 2022 and 2024) 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. The cover crop will be more conservatively managed going forward to avoid negative yield impacts.

A video was created to share with stakeholders: https://vimeo.com/891501928/772f6544c3?share=copy

Update:

View uploaded report

The long-term outcome of this study would be to inform manure management and cover cropping management to optimize crop yield and environmental benefits which will directly benefit soybean farmers by providing strategies that reduce risk through yield stability and potentially yield increase. Once 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.