Effects of solid dairy manure application on greenhouse gas emissions and corn yield in the Upper Midwest, USA

Authors: Young, Eric; Sherman, Jessica

Submitted to: Sustainability
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/17/2024
Publication Date: 12/20/2024
Citation: Young, E.O., Sherman, J.F. 2024. Effects of solid dairy manure application on greenhouse gas emissions and corn yield in the Upper Midwest, USA. Sustainability. https://doi.org/10.3390/su162411171.
DOI: https://doi.org/10.3390/su162411171

Interpretive Summary: Dairy manure is a key nutrient source for crops and can enhance soil fertility while reducing farm purchased fertilizer costs. However, manure may play a role in emitting greenhouse gases (GHG) after field application depending on manure type, application rates and equipment used. To better understand how solid manure impacts GHG emissions, an experiment was conducted at the Marshfield Agricultural Research Station in Stratford, Wisconsin from 2020-2023. The objective was to determine GHG emissions after application of two solid dairy manure types (bedded pack heifer manure, BP and separated dairy manure solids, SDS) on corn silage yield and GHG emissions (carbon dioxide, methane and nitrous oxide) compared to a no manure control. Plots were established in a grass hay field in spring 2020. Manure was applied in September 2020 at a rate equivalent to 300 kg N/ha. Background GHG emissions were monitored in 2020 and corn silage yields and GHG emissions were measured from 2021-2023. Results showed that BP had significantly greater carbon dioxide emissions in 2021 with no differences in 2022 or 2023. Emissions of nitrous oxide were negative with few significant manure impacts on emissions. Methane emission were 2 to 7 kg/ha/yr with no difference between treatments. Control corn yields were significantly greater in 2022 indicating a lack of available N from manure. Results indicate that soil type and tillage may be more important factors affecting GHG emissions than solid manure application in poorly drained soils.

Technical Abstract: Dairy manure is an important nitrogen (N) source but its role in greenhouse gas (GHG) emissions is not well understood. We evaluated impacts of two solid dairy manure sources (bedded pack heifer manure, BP and separated dairy manure solids, SDS) on corn silage (Zea mays) yield and GHG emissions (carbon dioxide, CO2; methane, CH4; nitrous oxide, N2O) compared to a no manure control. Plots were established in a grass hay (Lolium multiflorum) field in spring 2020 at the Marshfield Agricultural Research Station in Stratford, Wisconsin. BP and SDS were applied at 18.4 and 19.4 Mg dry matter/ha, respectively in September 2020. Corn was no-till planted each spring and GHG emissions and corn yield were monitored from 2020 to 2023. We found that BP had significantly greater CO2-C emissions in 2021 with no differences in 2022 or 2023. Besides a large N2O-N spike after application for BP, N2O-N emissions were very low with net negative emissions, indicating soil was mainly an N2O sink. Methane emissions were 2 to 7 kg/ha/yr with no differences among treatments. BP and SDS influenced soil temperatures in 2021 and 2022, possibly via soil moisture effects. Control corn yields were significantly greater in 2022 indicating a lack of available N from manure. Manure had a minor overall impact on GHG emissions despite the high application rate. Soil type and tillage may have an overriding effect on N2O-N and CH4-C emissions, suggesting GHG models should account for site-specific field conditions.