Carbon and Nutrient Contents in Soils From the King's River Experimental Watershed, Sierran Nevada Mountains, California.

Soil C and nutrient contents were estimated for eight watersheds in two locations (one high elevation, Bull, and one low elevation, Providence) in the King's River Experimental Watershed in the western Sierra Nevada Mountains of California. Eighty seven quantitative pits were dug to measure soil bulk density and total rock content, while three replicate surface samples were taken nearby with a bucket auger (satellite samples) to the same depth as surface pit samples. Results showed that the higher elevation Bull watersheds had significantly lower extractable P, exchangeable Ca2+ and Mg2+ and pH than the lower elevation Providence watersheds, presumably due to differences in leaching rates and degree of sol weathering (greater at Bull ). There were also significant differences among individual watersheds within the Bull and Providence locations that will be taken into account when treatments are imposed. Soil NH4+ and mineral N were surprisingly high in both the Bull and Providence watersheds and could not be related to any measured soil property or attributed to know rates of atmospheric deposition. Nutrient analyses on satellite samples were comparable to those taken from pits when averaged on a watershed or location (Bull and Providence) scale, but quite variable on an individual grid point basis. Elevated Zn values from the quantitative pit samples suggested contamination by field sieving through a galvanized screen. Had large rocks within them not accounted for with quantitative pit analyses, estimates of fine earth and associated C and nutrient contents would have been overestimated by 16 to 43%.