Effect of dairy manure-based fertilizers on nitrous oxide emissions in a semi-arid climate

Authors: Baxter, Abigail; Leytem, April; LIPTZIN, DAN - Soil Health Institute; Bierer, Andrew; AFSHAR, REZA - Dairy Management, Inc

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/5/2024
Publication Date: 9/25/2024
Citation: Baxter, A.E., Leytem, A.B., Liptzin, D., Bierer, A.M., Afshar, R.K. 2024. Effect of dairy manure-based fertilizers on nitrous oxide emissions in a semi-arid climate. Soil Science Society of America Journal. 88(6):1911-2370. https://doi.org/10.1002/saj2.20751.
DOI: https://doi.org/10.1002/saj2.20751

Interpretive Summary: In the United States, agriculture is responsible for 10% of total greenhouse gases emissions, with 55% of these emissions attributed to nitrous oxide losses from agricultural soil management (EPA, 2023). The use of manure products as an organic fertilizer remains a popular choice due to the high concentration of key nutrients such as nitrogen (N) and phosphorus (P), but can generate large N2O emissions as organic-N goes through nitrification, denitrification, and ammonia volatilization. In recent years, the adaptation and implementation of manure treatment technologies, such as anaerobic digestion, solid-liquid separation, and mechanical vapor recompression, have gain interest as means to generate more environmentally friendly manure-based fertilizers; however, more information is needed to understand how these products effect soil nutrients and greenhouse gases once applied in the field. In this study, we investigated the impact of two manure-based fertilizers produced by different treatment technologies on greenhouse gas emissions, soil nutrients, and crop yields in forage production regions commonly used in the Snake River Valley. We also investigated how fields with previous manure application may influence these products. Our results showed that there was a significant difference in greenhouse gas emissions between manure fertilizer products but minimal effect on soil nutrients or crop production. Previous manure application had a greater effect on soil nutrients, and more greatly influenced greenhouse gas emissions and crop yields in the first year following application. At this stage in the study, our results show that there is potential for certain manure-based fertilizers to successfully in mitigate greenhouse gas emissions in semi-arid systems without compromising crop yields.

Technical Abstract: Interest in manure treatment technologies that address challenges associated with nutrient management while minimizing environmental impacts, continues to grow. However, more research is needed to understand how manure treatment byproducts impact nutrient availability and greenhouse gas emissions. This study investigated the impact of two manure-based fertilizer sources (Dissolved Air Flotation [D] and Mechanical Vapor Recompression Solids [VR]) on nitrous oxide (N2O) and carbon dioxide (CO2) emissions, soil nutrients, and crop yields in a forage rotation. The study consists of three treatments applied in plots with manure history [M] or no manure history [NM] under a continuous corn (Zea mays) and triticale (x Triticosecale) rotation. Soil samples were collected, and forage yield was measured annually. Gas fluxes were measured throughout the year to determine daily and cumulative emissions. On average, M had significantly greater soil organic carbon (SOC),total carbon (TC), total nitrogen (TN), and reduced soil NH4-N. Corn yield was 7% lower on M vs NM plots in 2021 and 17% greater on VRNM vs non-manured control (CNM) plots in 2022. Triticale yield was 17% greater on M vs NM plots in 2021 and greatest on VR and DM plots compared to remaining NM plots in 2022. In general CO2 and N2O emissions were greatest on M plots (27-90% and 9-287%, respectively) in 2021 and on D and VR plots in 2022 (27-70% and 434-799%, respectively). Over both years, VR lost 1.9-2.2% of N-applied as N2O while D lost 0.4-0.8%. In semi-arid systems, D solids may provide a successful alternative to help reduce GHG emissions without compromising crop yield.