Location: Pasture Systems & Watershed Management ResearchTitle: Nitrous oxide emissions from manured, no-till corn systems
|PONCE DE LEON, MARIE - Pennsylvania State University|
|KARSTEN, HEATHER - Pennsylvania State University|
Submitted to: Nutrient Cycling in Agroecosystems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/8/2021
Publication Date: 3/26/2021
Citation: Ponce De Leon, M.A., Dell, C.J., Karsten, H.D. 2021. Nitrous oxide emissions from manured, no-till corn systems. Nutrient Cycling in Agroecosystems. 119:405-421. https://doi.org/10.1007/s10705-021-10131-y.
Interpretive Summary: The application of nitrogen fertilizers, both livestock manure and commercial inorganic forms, is a major source of emission of the greenhouse gas nitrous oxide. The use of winter crops in the manure injection can conserve nitrogen, thus reducing the amount of nitrogen applied to meet crop needs and potentially reducing the amount of nitrogen in the soil that can be converted to nitrous oxide. This study compared nitrous oxide emissions from soils planted to corn following three winter covers (alfalfa, clover, or no cover crop) and when manure was either injected or broadcast without incorporation into the soil. While adding winter crops to the dairy forage rotation reduced the amount of nitrogen applied, nitrous oxide emissions were not consistently reduced. Injection of manure increased direct emission of nitrous oxide. Statistical analysis indicated that the biggest factor influencing nitrous oxide emission was the time interval between addition of nitrogen sources and rainfall. While the tested practices have many benefits, greater reduction of nitrous oxide emission will require additional approaches to avoid nitrogen application shortly before heavy rainfall.
Technical Abstract: Crop rotations, organic nutrient amendments, reduced tillage practices, and the integration of cover crops have the potential to increase the sustainability of crop production, yet they can also impact nitrous oxide emissions. We investigated how different cropping system practices that include differences in crop residue types, N inputs, and timing of N applications influenced direct nitrous oxide emissions in dairy systems. In 2015 and 2016, nitrous oxide fluxes were measured from April to December using closed chambers in Pennsylvania. Gas emissions were sampled from soils planted to corn (Zea maize L.) following perennial forages and a green manure legume, all amended with dairy manure. In a corn-soybean (Glycine max L. Merr.) rotation we also compared emissions with inorganic fertilizer and two methods of dairy manure application: surface broadcast (without incorporation) and injection. Integration of perennials and the green manure reduced inorganic N fertilizer use, however nitrous oxide emissions were not reduced compared to applying only inorganic fertilizer following soybeans. Emissions were higher 15 to 45 days after manure was injected compared to treatments where manure was broadcast. In these no-till systems, 0.4 to 1.8% of N added was lost as nitrous oxide. Random Forest analysis identified the most important variables driving nitrous oxide emissions as: time after manure application, time after previous crop termination, soil nitrate, and soil moisture. These results suggest that synchronizing N inputs with crop uptake, and avoiding N applications when there is a high chance of heavy precipitation can reduce potential nitrous oxide losses.