Carbon Sequestration and Mitigation of Agricultural Greenhouse Gas Emissions through management: Insight from an incubation experiment

Climate change poses a significant threat to soil quality and global food security, with projections indicating potential crop yield declines of 17% by 2050. Simultaneously, agriculture contributes to an estimated 24% of all greenhouse gas (GHG) emissions. The dynamics of carbon (C) and nitrogen (N) play a pivotal role in GHG emissions and soil C sequestration, yet further research is needed on how management practices influence these dynamics. To address these challenges and provide data can facilitate efficient resource utilization in agricultural production, an incubation experiment was conducted to provide data on the impact of management options on C sequestration and GHG emissions from agricultural soils. The experiment took place in 850 mL glass jars under controlled conditions at 60% water-filled pore space and a temperature of 25C. Composite soil samples, derived from a moderately fertile soil (2-3% SOC) from Grabenegg, Austria, at a depth of 0-15 cm, were subjected to five treatments: 1) control, 2) labeled urea, 3) inhibitor and labeled urea, 4) biochar + 15N labeled urea, and 5) inhibitor and biochar and labeled urea. The 15N-labeled urea (5% atom excess) was applied at a rate of 150 kg N ha-1, while biochar was applied at 2% of the soil by dry mass basis. A neon inhibitor which includes NBPT to limit nitrogen loss into the atmosphere as ammonia and DCD to reduce leaching, were applied at a rate of 4 mL per 100g urea as instructed by the manufacturer. All treatments were replicated four times. Soil and gas samples were collected on days 1, 3, 8, 15, 24, 31, 38, 45, 52, and 59 after treatment application. Gas samples were collected over a two hour period each day. Soil samples were analyzed for pH, soluble organic C, and mineral-N (NH4+, NO3-), while gas samples were analyzed using a gas chromatograph (GC) for NO2, CO2, and CH4. Preliminary results indicate that the addition of biochar increased soil C content, aligning with expectations from prior studies and that the addition of the inhibitor had a discernible impact on the pathways of nitrogen in the study samples. The use of isotopic methods and GHG measurements can furnish critical data supporting the most efficient use of resources for both climate mitigation and adaptation.