Animal manure applied to farm fields is often discussed as a major contributor to nutrient loading in streams and a primary driver of harmful algal blooms. Most manure in the Western Lake Erie Basin is applied on bare soil in the fall, without crops to capture the available nitrogen and phosphorus.
Years of previous on-farm research has demonstrated that applying manure into a growing corn crop — also called side-dressing — has numerous benefits: it allows crops to more effectively captures nitrogen in manure, reduces the potential for phosphorus loading in the soil, and often increases corn yields and farm profitability.
Ohio State Water Quality Extension Associate Courtney Krieger collected soil samples, measuring properties such as pH, organic matter, extractable nutrients and soil nitrate and ammonium.
However, researchers needed data to robustly demonstrate these effects and evaluate potential reductions in nutrient loading.
Through experiments conducted on 20 fields across Ohio, researchers tested the benefits of side-dressing manure. They also evaluated the role of soil health in reducing corn crops’ demand for nitrogen. Over two years, the team analyzed more than 400 soil samples, 800 plant tissue samples, 16 manure samples, and 120 water samples. Aerial photography from drones provided additional insights into plant health and growth.
Findings indicate that manure applied as a side-dress, compared to conventional nutrient application using fertilizers, increased or maintained similar levels of nutrient concentration in corn tissue. Side-dressing manure into growing corn resulted in a significant increase in corn yield by 13% across 12 trials. Other experiments showed that fields with regular manure applications can reduce total nitrogen application requirements.
Additionally, comprehensive analysis of water quality data confirmed similar nitrogen and phosphorus losses between manure and conventional fertilizers, reinforcing the benefits of manure applications. Soil health indicators were found to be reliable predictors of nitrogen inputs, and economic evaluations demonstrated the cost-effectiveness of these practices.
As a whole, the project provided strong evidence supporting the use of side-dressed manure as a sustainable and efficient method for improving corn growth, soil health, and farm profitability all while mitigating nutrient losses. Notably, through the team’s collaborative efforts, participating farmers were able to implement sustainable agricultural practices that significantly improved soil health on their land.
For more information about this research, contact Deiss at deiss.8@osu.edu. To learn more about other completed HABRI projects, read the 2024 HABRI annual report.
Ohio Sea Grant is supported by The Ohio State University College of Food, Agricultural, and Environmental Sciences (CFAES) School of Environment and Natural Resources, Ohio State University Extension, and NOAA Sea Grant, a network of 34 Sea Grant programs nation-wide dedicated to the protection and sustainable use of marine and Great Lakes resources. Stone Laboratory is Ohio State’s island campus on Lake Erie and is the research, education, and outreach facility of Ohio Sea Grant and part of CFAES School of Environment and Natural Resources.