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Home , Carbon offset, Carbon sequestration

Challenging Change and with Healthy : The -Water-Climate Connection

An often-overlooked resource to help meet its ambitious and water conservation goals is right beneath our feet. Soils can be significant sinks for atmospheric , and increasing carbon can increase California’s water storage capacity. In Gov. Brown’s State of the State proposal he calls “to increase carbon in soil and establish long term goals for carbon levels in all California’s agricultural soils.” Rising air temperatures are projected to continue to drive up urban, agricultural, and rangeland water use, straining both surface and groundwater resources. Scientific studies (see supporting literature) have shown that managing , ranches, and public lands to increase can increase water-holding capacities and crop yields, reduce erosion, increase their capacity to sequester carbon in soils and vegetation, and reduce climate-related water deficits. strategies such as “” have a critical role to play in helping California develop resilience to while simultaneously reducing atmospheric greenhouse gases. “Carbon Farming” is a systems approach to land management that involves implementing practices that can improve the rate at which (CO2) is removed from the and converted to plant material and/or . Some practices include: . using ecological site assessment and mapping in conservation planning . using dynamic carbon models to predict and measure increases in -system terrestrial carbon stocks . using hydrologic modeling to evaluate potential long-term impacts to on-farm water resources . integrating hedgerows, windbreaks and riparian buffers in farm plans . applying composted urban and agricultural organic waste materials to grasslands and croplands Benefits of Carbon Farming include: . reduction of urban and agricultural organic waste, . improvement in soil health, forage and crop yields, . increase in soil water holding capacity and reduction in total landscape demand for water, . and reduction of atmospheric greenhouse gases (GHG). Science to Inform Land and Water Management The Marin Carbon Project (MCP) is a consortium of leading agricultural institutions and producers in Marin County, university researchers, county and federal agencies, and nonprofit organizations. MCP is collaborating with the USGS on studies focused on rangelands, which cover over half the land area of California, and have the potential to mitigate and increase stored soil water. Scientific studies by the Marin Carbon Project have shown: . Application of increased rangeland forage production by 50% and soil carbon sequestration by 3 ton per hectare over 3 years, with no increase in other GHG. . Net ecosystem carbon storage increased by 25-70% . Soil carbon content increased, along with forage quality, water holding capacity and plant growth, driving continued sequestration of soil carbon over time. . Sequestration of just one metric ton of C per hectare per year on half the rangeland area in California would capture 42 million metric tons of CO2e, offsetting the annual GHG emissions from energy use for both commercial and residential sectors. . Model results show that combining multiple carbon farming strategies leads to significant increases in the capacity of working lands to sequester carbon. USGS tools used to evaluate local and regional water resources include: . Watershed recharge and runoff quantification to assess water availability . Climatic water deficit estimation – to assess demand or landscape stress (climatic water deficit is the amount of water plants would use if it were available) . Spatial distribution of hydrologic processes in watersheds – for resource planning and infrastructure development POTENTIAL BENEFITS of CARBON FARMING for WATER STORAGE:

The USDA Natural Resources Conservation Service suggests 5% Potential organic matter (OM) content as an indicator of healthy soil and that an increase of 1% OM in soils is equivalent to 1” of increased water holding capacity (WHC). If the OM of ALL soils in California was increased to 5%, then the potential increase in WHC (shown left) is equal to almost 28 million acre-feet. Within the Rangeland Coalition focus area (see Byrd et al. 2015) alone, there is nearly 8 million acre- feet of potential increase in soil WHC, equal to about 8 Folsom Lakes. Additional research is needed to identify and prioritize soils having the highest probability of responding to efforts to increase OM. Increasing the amount of soil water, which reduces climatic water deficit (CWD), has multiple benefits: • reducing demand (the need for irrigation) • reducing risk • reducing vegetation stress and vulnerability to disease • increasing forage and crop yield through enhanced carbon capture Water that stays in the watershed can serve to preserve baseflows and riparian systems during low-flow periods. See figure at left illustrating the calculation, using a hydrologic model (Flint et al., 2013), of a reduction in CWD of 0 to 4.5 inches per year with a 25% increase in WHC due to increase in soil OM for the northern Sacramento Valley.

Decrease in POTENTIAL FUTURE CWD for 1998 (inches of water RESEARCH per year)  Apply field-research results to models, providing tools to prioritize soils statewide for organic matter (soil organic carbon) enhancement efforts. Achievements of the Marin Carbon Project: . American Carbon Registry and CA Association of  Quantify resulting benefits in Air Control Officers’ Association ecosystem services--particularly accepted rangeland compost protocol to generate water benefits--under current credits. and future climate scenarios. . Development of a new National Resource  Conservation Service (NRCS) on-farm carbon Quantify GHG sequestration for sequestration quantification tool, COMET-Planner. various model scenarios. . Carbon Farm Planning process template  Field test carbon sequestration developed by Marin Carbon Project. strategies on priority soils to evaluate degree of water Supporting Literature: benefits. DeLonge, M.S. et al. 2014, Greenhouse gas mitigation opportunities in California , Nicholas Institute for Environ. Policy Solutions Report. Ryals, R., and Silver, W.L., 2013, Effects of organic matter amendments on net primary productivity and green house gas emission in annual grasslands, Ecol. Applications, 23(1), 46-59. DeLonge, et al., 2013, A lifecycle model to evaluate carbon sequestration potential and greenhouse gas dynamics of managed grasslands, , 16(6), 962-979. Swan, A. et al. COMET-Planner: Carbon and Greenhouse Gas Evaluation for NRCS Conservation Practice Planning, a project report to USDA/NRCS. Flint, L.E. et al. 2013, Fine-scale hydrological modeling for climate change applications; using watershed calibrations to assess model performance for landscape projections; Ecol. Proc. 2:25. Byrd, K. et al. 2015, Integrated Scenarios and Outreach for Assessing Contacts: Threats to Ecosystem Services on California Rangelands, Landscape Ecol. MCP: Jeffrey Creque, [email protected] DOI 10.1007/s10980-015-0159-7. USGS: Lorraine Flint, [email protected]