358-9 Assessment Of Soil Nitrous Oxide Emissions (N2O) In Forage Systems Fertilized With Dairy Liquid Manure.

Poster Number 1218

See more from this Division: ASA Section: Environmental Quality
See more from this Session: Greenhouse Gas Emission Methodology and Analyses

Wednesday, November 6, 2013
Tampa Convention Center, East Exhibit Hall

Cristina Lazcano1, Alia Tsang1, G. Stuart Pettygrove1, William R. Horwath2 and Martin Burger3, (1)Land, Air and Water Resources, University of California Davis, Davis, CA
(2)Department of Land, Air and Water Resources, University of California-Davis, Davis, CA
(3)Dept. LAWR, University of California-Davis, Winters, CA
Abstract:
Excessive N inputs through fertilization significantly increase the potential for large nitrous oxide (N2O) emissions from soils. Intensive dairy production generates large amounts of liquid manure which is typically reused as fertilizer for the production of forage, together with inorganic N fertilizers. Thus, these systems typically receive high annual inputs of N, having a great potential for large N2O emissions. The present study was carried out in three dairy forage corn production fields of the Central Valley of California representing a range of soil textures and where liquid manure was applied in irrigation water together with inorganic N fertilizers. The objectives of the study were to determine (i) the proportion of the N inputs emitted to the atmosphere as N2O, and (ii) the main sources (manure vs. inorganic N fertilizer) of the N2O. Total N inputs, crop N removal and N2O emissions were assessed over two corn cropping seasons at each farm, together with soil inorganic N (NH4+-N, NO3--N, NO2--N), moisture and temperature. Field data was completed with laboratory incubations of the three soils with liquid manure and 15N labeled inorganic fertilizers in order to determine the proportion of liquid manure and inorganic N in the emitted N2O. Preliminary results show that emissions ranged from 4.7-7.4 kg N2O-N ha-1 in sandy soils and from 11.4-16.5 kg N2O-N ha-1 in a clayey soil. Also, periods of N2O release after irrigation events were longer in the clayey than in sandy soils. Emissions represented between 0.65 and 3.53% of the initial applied N and were explained by high soil moisture and concentrations of soil inorganic N as showed by multiple regression analysis. Results of this study provide important information to understand N2O release dynamics in dairy forage production systems which can be used to improve fertilizer management and reduce environmental impacts.

See more from this Division: ASA Section: Environmental Quality
See more from this Session: Greenhouse Gas Emission Methodology and Analyses