Estimating Spatial Variations of Soil Water Content Using Noncontacting Electromagnetic Inductive Methods

Abstract

ing spatial variations of soil water content using noncontacting electromagnetic inductive methods. Can. J. Soil Sci. 68:715-722.The relationships among the spatial variations of soil water content, soil texture, soil solution electrical conductivity, and bulk soil electrical conductivity were examined for a field characterized by net drainage and low concentrations of dissolved electrolytes. Bulk soil electrical conductivity was measured over various depths at 52loca-tions within a 1.8-ha field using noncontacting electromagnetic inductive meters. Soil water content (0-0.5 m depth) was measured at the same locations using the time domain reflectometry method. Measurements of soil texture and soil solution conductivity were obtained from core samples from-37 of the sampling locations. Soil water content at the site ranged from 0.06 to 0.36 m j m '. Clay content ranged from 2.5 to 44% percent and bulk soil electrical conductivity ranged from 0.0 to 0.21 S m-1. Significant correlation existed among almost all ofthe measured variables. Regression analysis indicated soil solution conductivity had no effect on measured bulk soil electrical conductivity for soil water contents less than 0.25 m3 m-t. Bulk selected to obtain the maximum variation in 0" and texture across the site (Fig. l). RESULTS AND DISCUSSIONSand content in the 0-to 0.5-m depth of the study area varied from 5 to70% and clay content from 2.5 to 44.0% (Table 1)

Mapeamento da condutividade elétrica e relação com a argila de Latossolo sob plantio direto

“…Segundo Kachanoski et al (1988), os íons presentes na dupla camada difusa de partículas de argila são capazes de conduzir eletricidade, mesmo sob baixos teores de água no solo, ao passo que a areia praticamente não apresenta esta característica. Assim, os resultados de CE em solos argilosos são, geralmente, mais altos que em solos mais arenosos.…”

Apparent soil electrical conductivity mapping as an agricultural management tool in arid zone soils

“…Techniques for predicting soil salinity from EC a survey data have been discussed by numerous authors, including Williams and Baker (1982), Rhoades et al (1989Rhoades et al ( , 1999, Hendrickx et al (1992), Rhoades (1992Rhoades ( , 1996, and Lesch et al (1995a). Other soil properties that have also been successfully mapped using EC a data include clay content (Williams and Hoey, 1987), depth to clay layers (Doolittle et al, 1994), and moisture content (Sheets and Hendrickx, 1995;Kachanoski et al, 1988). Additionally, yield potential has been shown to be directly related to EC a data in many applications (Jaynes et al, 1993;Sudduth et al, 1995;Kitchen et al, 1999;Johnson et al, 2003).…”

Improving Map Accuracy of Soil Variables Using Soil Electrical Conductivity as a Covariate

“…Soil EC is a measurement that is affected primarily by a combination of soil water content, dissolved salt content, clay content and mineralogy and soil temperature (McNeill, 1980a). Soil EC measured by EMI has been correlated with clay content (Williams and Hoey, 1987;Doolittle et al, 1994), soil water content (Kachanoski et al, 1988;Sheets and Hendrickx, 1995), sand deposition (Kitchen et al, 1996), total soluble salts (Williams and Hoey, 1987), yield (Jaynes et al, 1995), and soil available N (Eigenberg et al, 2002). Therefore, soil EC data may serve as a covariate and noninvasively provide valuable and inexpensive information to aid in the production of more accurate soil maps for certain variables (Jaynes, 1996).…”