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Research Project: Towards Resilient Agricultural Systems to Enhance Water Availability, Quality, and Other Ecosystem Services under Changing Climate and Land Use

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Title: Soil greenhouse gas (CO2, N2O and CH4) flux meansurements from grazing pastures using automated system

Author
item BAJGAIN, RAJEN - University Of Oklahoma
item XIAO, XIANGMING - University Of Oklahoma
item BASARA, JEFFREY - University Of Oklahoma
item Steiner, Jean

Submitted to: American Geophysical Union
Publication Type: Abstract Only
Publication Acceptance Date: 8/6/2018
Publication Date: N/A
Citation: N/A

Interpretive Summary: Abstract only

Technical Abstract: Agricultural production and decisions in management contribute 21-25% of all global CO2, 55-60% of CH4, and 65-80% of N2O. Cattle systems are responsible of 65% of GHG fluxes globally; while it contributes a 71% of the total livestock emissions in United States. GHG emissions show high spatial and temporal variability due to large variation to factors as weather conditions (soil temperature and soil moisture), availability of decomposable organic matter, mineralizable carbon and addition of nitrogen, which are governed by management practices such as cattle grazing and fertilizer application. Chemical fertilizer and urine plays an important role in nutrient cycling in grazed pasture systems. Addition of nitrogen (cattle urine and chemical fertilizers) to the soil produce changes in soil pH, soil microbial community and nutrient cycle. The study general objective is understanding the contribution of N addition to GHG emissions from grasslands. To address the temporal and spatial variability of gas fluxes due to addition of N, we designed an automated system by combining an automated chamber system and Fourier Transform Infrared Spectroscopy (FTIR) multi-gas analyzer in parallel to allow frequent automated simultaneous gas flux measurements (every 27 minutes) from 9 automated chambers. Preliminary data showed there was a significant difference on the interaction of GHG fluxes and N addition. The background CO2, N2O and CH4 fluxes from the grazed pasture (control) were about 8, 0.04 and 0.08 µmol m-2 s-1 respectively, in April and 14, 0.03 and 0.2 µmol m-2 s-1 respectively in June. However, maximum fluxes coincide with high soil moisture. The signals for N2O fluxes were more pronounced after about 30-40 hrs of rainfall. Knowing the effect of addition of N sources and its interaction with climate factors on GHG production over time would allow a better interpretation of the overall impact of cattle grazing systems.