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Title: CHARACTERIZING SPATIAL VARIABILITY AT LANDSCAPE SCALES WITH ECA-DIRECTED SOIL SAMPLING

Author
item Corwin, Dennis
item KAFFKA, STEPHEN - UC DAVIS, CA
item LESCH, SCOTT - UC RIVERSIDE, CA
item OSTER, JAMES - UC RIVERSIDE, CA

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 9/8/2003
Publication Date: 11/5/2003
Citation: Corwin, D.L., Kaffka, S.R., Lesch, S.M., Oster, J.D. 2003. Characterizing spatial variability at landscape scales with ECa-directed soil sampling. Soil Science Society of America. Paper No. S05-corwin392673-O.

Interpretive Summary:

Technical Abstract: Characterizing spatial variability of soil properties at landscape scales is important for solute transport modeling, precision agriculture, and soil quality assessment. Spatial measurements of apparent soil electrical conductivity (ECa) are potentially useful for characterizing spatial variability. A preliminary soil quality assessment was conducted at a 32.4-ha site in the San Joaquin Valley of central California. The objective was to acquire spatial measurements of ECa from mobile EM equipment to direct soil sampling that characterizes the spatial variability of properties related to soil quality of an arid-zone soil used in a drainage water reuse study. Using the EM data and a response-surface sampling design, 40 sites were selected that reflected the spatial variability of the ECa measurements. Soil-core samples were taken at 0.3-m intervals to a depth of 1.2 m and analyzed for 28 physico-chemical properties (e.g., salinity varies from 12.8-36.6 dS/m, SAR from 28.8-88.8, clay content from 2.5-48.3%, B from 11.5-32.2 mg/L, and Mo from 476.8-1959.6 g/L, etc.). Maps created with a GIS show spatial distributions of the soil properties. Data indicate that sustainability of drainage water reuse at this location depends upon maintaining sufficient leaching to manage salinity, B, Mo, and Na levels. A supplementary stratified random sampling design would help spatially characterize any soil quality properties not highly correlated with ECa.