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Title: EFFECT OF SOIL WATER ON APPARENT SOIL ELECTRICAL CONDUCTIVITY AND TEXTURE RELATIONSHIPS IN A DRYLAND FIELD.

Author
item MCCUTCHEON, M. - NCWCD
item Farahani, Hamid
item STEDNICK,, J. - COLORADO STATE UNIVERSITY
item Buchleiter, Gerald
item Green, Timothy

Submitted to: Biosystems Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/6/2006
Publication Date: 3/24/2006
Citation: Mccutcheon, M.C., Farahani, H., Stednick,, J.D., Buchleiter, G.W., Green, T.R. 2006. Effect of soil water on apparent soil electrical conductivity and texture relationships in a dryland field. Biosystems Engineering.(2006) 94 (1), 19-32

Interpretive Summary: An EC mapping devise was used to map soil characteristics of a half section of wheat-fallow strip cropping field near Fort Collins, Colorado in 2001 and 2002. Our objective was to determine the relation between EC and soil properties. Soil samples were collected from 198 locations within the field and analyzed in the laboratory for water content and texture (percent sand and clay content) among other properties. Results show soil water content and elevation as the dominant factors affecting EC, with all other measured soil properties (such as sand, silt, clay, bulk density) having nearly equal, but weak to moderate, correlations with EC. Mapping of EC showed the relative patterns of soil water content across the field. While soil texture was weakly predicted from EC maps in this dryland wheat-fallow field, EC maps can be used as a tool to quickly and economically identify major changes in soil across the field to improve soil and crop management decisions.

Technical Abstract: In non-saline fields, bulk soil electrical conductivity (ECa) has shown to be primarily a function of soil water and clay content, but results from literature are mixed and site-specific. That limits the practical utility of ECa to map soil properties. Our objective was to explore ECa relations with soil properties in a 110 ha field of 12 alternating wheat-fallow strips that provided two concurrent levels of soil water profiles during a period of regional drought in Colorado. Measurements included multiple field-scale ECa mappings, complemented with extensive soil profile sampling (198 locations) and laboratory analysis. Water content and elevation are the dominant factors affecting ECa, with sand, silt, clay, bulk density, EC1:1, CaCO3, and pH1:1 having nearly equal, but weak to moderate, correlations with ECa. Mapping of ECa can show the relative spatial patterns of soil water content. Results show ECa versus soil properties relations vary with time. For the dryland field examined herein, ECa maps represent overall soil variability, but none of measured soil properties can be accurately mapped from ECa maps.