Enhancing Soil Organic Sarbon Storage Through Forested Buffers and Biochar Application in Agricultural Lands

Non-Peer Reviewed

Tailoring agricultural management practices to increase soil organic carbon (SOC) storage and reduce greenhouse gas (GHG) emissions can improve the ecological goods and services generated by agricultural land. We conducted a 4-yr field study in central Alberta, Canada in two common types of agroforestry systems: hedgerows (legacy perennial vegetation buffers that include a woody component) and shelterbelts (planted woody perennial vegetation at field margins). In adjacent cropland, we compared manure compost (MT) and biochar (BT, charred MT) applications with a control (CT, no treatment). We also compared SOC and GHG emissions between CT and adjacent perennial vegetated areas, either with (+WT) or without (-WT) a woody component. Within croplands, there was a trend for increased CO2 emissions and water-soluble organic C (WSOC) in MT compared to both BT and CT. Additionally, decreased microbial biomass C in both MT and BT relative to CT indicates the increased WSOC in MT may not have contributed to microbial growth, instead reflecting inefficient respiration. Increased SOC concentrations were retained in the cropland surface soil of BT, but not MT, plots two years post application. Hedgerow systems contained substantially more SOC under perennial vegetation, particularly in the +WT subplots, relative to the cropland to 100 cm in depth, primarily due to increased particulate organic matter. Shelterbelt system SOC storage was similar across the component land uses. The cropland also had less SOC physically protected in aggregates relative to adjacent soil under perennial vegetation. Overall, our preliminary results show that biochar, rather than manure, application increased agricultural SOC storage while not increasing GHG emissions. Further research is warranted to assess large-scale cropland application of manure-derived biochar, including a life-cycle analysis to determine the C footprint. Additionally, we show that retaining legacy perennial vegetation buffers with a woody component (hedgerows) is more effective than planting of shelterbelts to increase SOC protection and storage on agriculture land in both surface and deep (to 100 cm) soil layers. Policy and C sequestration initiatives should incentivize the retention of hedgerows on agricultural land. Link to Video Presentation: https://youtu.be/fZSRm6DfzG8