Effects of Nitrogen Fertilizer on Switchgrass Productivity and Soil Trace Gas Production

Abstract

Atmospheric greenhouse gas (GHG) concentrations continue to increase and one of the major culprits is the continued elevation and use of fossil fuels for energy. Using bioenergy, a renewable and sustainable source of natural energy, could help to reduce the effect that fossil fuels are having on the planet by slowing the rate of input of atmospheric GHG’s. Perennial crops such as switch grass can be grown and used as a bioenergy crop. In some cases, nitrogen fertilizers are used to increase the growth of bioenergy crops with potential negative environmental consequences. For example, nitrogen fertilizer can impact soil chemical processes and lead to an increase in the production of greenhouse gases, mainly N2O and CH4. Production of these gases would negate some of the benefits achieved by substituting bioenergy crops for fossil fuels. When I examined the amount of gas flux being produced by switchgrass fields, with 0 lbs/acre, 50 lbs/acre and 150lbs/acre fertilizer treatments we observed, as predicted, an increase in N2O production with more fertilization. In some cases the increase in N2O production in the 150lbs/acre treatment was as extreme as being over 200% larger compared with no fertilization. I also observed some very interesting results with methane production, which has been showing production of methane, along with after around 30 minutes of gas collection in a chamber. Based on the results of my research, I have created a cost benefit analysis of using nitrogen fertilizer on switchgrass crops.