Greenhouse Gas Life Cycle Analysis of Biochar Effects on Marginal Land Conversion to Switchgrass Production
Pasture Systems & Watershed Management Research
2013 Annual Report
1a.Objectives (from AD-416):
There are three major objectives to this research. The first is to quantify carbon sequestration, greenhouse gas emissions, and biomass yield for a managed switchgrass crop compared with unmanaged vegetation on marginal lands. The second is to compare direct incorporation of biochar prior to planting with a novel method to annually inject biochar into the soil at the same time as fertilizer applications. The third is to conduct a life cycle analysis to quantify the net global warming potential of each management strategy and compare them with unmanaged lands.
1b.Approach (from AD-416):
Soil respiration and N2O and CH4 emissions will be monitored on switchgrass that will receive biochar at 10 Mg/ha in one application prior to planting or at 2 Mg/ha in each of five annual applications. Soil carbon (C) and nitrogen (n) N content will be monitored annually to a depth of 1.0 m. A life cycle assessment of greenhouse gas sources and sinks for each system will be conducted. Additional data to be collected will include volumetric soil water content, bulk density, air temperature, solar radiation, and rainfall. Weather data will be collected continuously during the growing season. Algorithms will be developed to quantify the effect of biochar on the measured soil properties.
Biomass was harvested in the fall, and first-year biomass yield showed a small, but non-significant increase in plots containing biochar. The second application of biochar was applied to the plots receiving yearly furrow applications. All switchgrass plots were fertilized in the spring with 60 kg N/ha and N2O emissions were monitored at all locations for approximately one month following fertilization. As anticipated, preliminary observations suggest that N2O emissions were greatest from the typically wet soils but little emissions occurred from the drier sites.