Speaker | UC Davis
Davis, CA | firstname.lastname@example.org
Jessica Chiartas is a PhD Candidate in Soils and Biogeochemistry researching the impacts of agricultural management on soil carbon and overall metrics of soil health. After five years in corporate sales, most recently in pharmaceutical sales selling antibiotics, she became fascinated by microbes and their role in everything from human health to agriculture and the environment. Recognizing soils as fertile ground for solutions to global challenges, she returned to graduate school to gain a depth of knowledge with the ultimate goal of translating and communicating soil science to a broad audience. She frequently conducts seminars, trainings, and workshops on science communication and is currently supported by a USDA-NRCS grant to develop a website and a series of short videos and infographics that communicate the value and importance of soil.
Session Time: Thursday, January 30, 2:00 to 3:30 PM
Presentation Title: Digging Deeper: How Compost and Cover Cropping Sequester Soil Carbon
Presentation Description: Increasing soil organic matter (SOM) via organic inputs is a key strategy for increasing long‐term soil carbon (C) storage and improving the climate change mitigation and adaptation potential of agricultural systems. Due to their hot and dry climates, semi-arid regions tend to have low SOM contents providing both an opportunity and a challenge for sequestering soil C. A recent long‐term trial in California revealed that the combined use of composted poultry manure and winter cover crop has the potential to sequester significant amounts of SOC in California soils, despite such climatic challenges. SOC was measured at the initiation of the experiment and at year 19, at five depth increments down to 2 m. Across the entire 2 m profile, SOC increased by 12.6% (21.8 Mg C/ha) with the combined use of WCC and composted poultry manure. This amounts to a 0.7% annual increase, well-exceeding the ambitious goals of the global 4 per Mille initiative.
The addition of WCC to a conventionally managed system increased SOC stocks by 3.5% (1.44 Mg C/ha) in the 0–30 cm layer, but decreased by 10.8% (14.86 Mg C/ha) in the 30–200 cm layer, resulting in overall losses of 13.4 Mg C/ha. If we only measured in the top 30 cm, we would have assumed an increase in total soil C with WCC alone, whereas significant losses occurred when considering the entire 2 m soil profile. Ignoring the subsoil carbon dynamics in deeper layers of soil may lead to false conclusions about impacts of management and fails to recognize potential opportunities for increasing soil C sequestration.