Carbon Distribution in Selected Organic-Rich Soils of the California Delta.

The California Delta is an important and ecologically-sensitive agricultural area with over 97,000 hectares of farmland, producing diverse crops such as corn, asparagus, tomatoes, grapes, and stone fruit. Much of the land is below sea level and consists of a system of islands protected by levees. Degradation of the Delta’s soils, especially its Histosols, is a major concern. In many areas, several meters of soil have been lost through the oxidation of organic matter (OM) as well as wind erosion.

As part of the USDA-NRCS’ Bay Delta Initiative, the Hanford Soil Survey Office launched the MLRA 16 Bay Delta Soil Systems Study in 2012. The overall project objective is to provide a foundation of reliable field and laboratory data of major (benchmark) soils in the Delta. Data collected will be used to improve soil maps and interpretations, leading to improved conservation planning and preservation of these soils.

Objectives of this paper are to discuss characteristics of selected pedons. Total carbon (C) as well as forms of OM (peat, muck) were evaluated with depth. Other data include rubbed and unrubbed fiber, pyrophosphate color, mineral content, and PSDA. Results from this study will be important to understand pedogenic differences between soils at different sites across the Delta. Also these data will document the form and stability of C, and provide better evaluation of C loss from agriculture land use in this area.