Variation of Soil Properties On Alluvium From Three Rivers in the Lodi Wingrape District.

The Lodi Winegrape District, located on the east side of California’s San Joaquin Valley, is one of the largest wine districts in California and encompasses a wide range of winegrape varieties, production systems, and soils. Winegrape nutrient management, particularly K, is complicated by this soil diversity. Soils have formed on alluvium from the Mokelumne, Cosumnes, and Calaveras River in this district, and soil properties vary as a result of alluvium composition, which is a result of the extent to which source watersheds extend eastward into the granitic rocks of the Sierra. Large rivers, like the Mokelumne and Cosumnes, extend to the crest of the Sierra, and erode extensive areas of granitic rocks.  South of the Mokelumne, the Calaveras River watershed is much less extensive, and has its headwaters in the metasedimentary and metavolcanic rocks of the Sierran foothills and lower Sierra Nevada. Although the Mokelumne and Cosumnes River extend to the crest of the Sierra, the Mokelumne River watershed is much larger than the Cosumnes River watershed, and may cause wider variation in alluvium texture and mineralogical composition. Soils on Mokekumne River alluvium have the coarsest textures; soils on Calaveras River alluvium have the finest textures, and soils on Cosumnes River alluvium have intermediate textures. Field and lab studies of soils in these watersheds show diverse soil properties, especially K behavior, due to combinations of parent material composition and particle size distribution.