Impact of Residue Grazing and Baling on Greenhouse Gas Fluxes Under Irrigated System.

Assessment of soil gas fluxes and microbial properties under different residue management scenarios is important to understand C and N cycling as well as soil biological activity. Corn residue is a livestock forage and biofuel feedstock. However, indiscriminate removal of residue can reduce C input and change micro-climatic conditions affecting microbial activity and C and N gas fluxes. There is limited information on the impact of corn residue grazing and baling on soil health parameters such as microbial community and gas fluxes. Therefore, we determined the impact of corn residue grazing and baling on gas fluxes (CO₂ and N₂O) and microbial community in an irrigated continuous corn system in Nebraska. The study site was established in 2014 and has three corn residue treatments replicated thrice: 1) baling 2) grazing 4) control (no grazing and no baling). Gas fluxes are being measured every 15 days in spring and every month in summer and winter of year 2016 and 2017. Microbial community will be determined using fatty acid methyl ester (FAME) analysis in spring 2017. During 2016, all treatments had similar cumulative gas fluxes, however, the gas fluxes were lowest for baling in spring compared to control and grazed treatment. Such results could be due to lower residue amount and moisture regime in baled plots compared with grazed and control. For microbial community, we hypothesized that baling will have lowest microbial biomass due to low C input while grazing can have the highest amount microbial biomass due to input of manure by grazing cattle. Overall, the results will be helpful in better understanding the impact of residue grazing and baling on soil health.