Description

The spatial variability of physical soil properties at the field scale is increasingly important in agriculture and natural resource management. Changes in topography, parent material, management practices, erosion/deposition rates, etc. can influence the variability of the soil’s physical properties and help guide management and land use plans. The Geonics EM38 is a noninvasive geophysical sensor which is used to measure the apparent electrical conductivity (ECa) of the soil through electromagnetic induction – primarily influenced by clay content, soil moisture content, and salinity. Soil moisture has been found to be a significant contributor to ECa and is therefore useful in determining both spatial and temporal variation in available soil water content across a landscape. This study conducted at the Lake Wheeler Research Facility in Raleigh, North Carolina examined the ability of EM38 to quantify and map the topographic relationship and variability of soil moisture content of the soil surface (0 -.15m). Soil cores were collected at 14 locations and used to determine soil particle size, bulk density, and available water content. Multiple EM38 surveys were conducted along transects of a rain-fed agricultural field and used to calibrate readings with volumetric water content. Data and maps developed with ArcGIS software will be presented of ECa survey measurements, water retention curves, particle size analyses, and bulk densities for soil cores collected. The goal of the study was to determine how soils – and associated moisture content – vary spatially and if this variability can be detected using EM38 sensor techniques.

Location

Stewart Center, Room 218

Start Date

11-2015

Document Type

Event

Keywords

EM38, Spatial Variability, Soil moisture, Soil, Agriculture, Precision Management

Session List

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Nov 1st, 12:00 AM

CHARACTERIZING AND MAPPING THE FIELD SCALE SPATIAL VARIABILITY OF SURFACE HORIZON SOIL PROPERTIES AND WATER CONTENT WITH NONINVASIVE EM38

Stewart Center, Room 218

The spatial variability of physical soil properties at the field scale is increasingly important in agriculture and natural resource management. Changes in topography, parent material, management practices, erosion/deposition rates, etc. can influence the variability of the soil’s physical properties and help guide management and land use plans. The Geonics EM38 is a noninvasive geophysical sensor which is used to measure the apparent electrical conductivity (ECa) of the soil through electromagnetic induction – primarily influenced by clay content, soil moisture content, and salinity. Soil moisture has been found to be a significant contributor to ECa and is therefore useful in determining both spatial and temporal variation in available soil water content across a landscape. This study conducted at the Lake Wheeler Research Facility in Raleigh, North Carolina examined the ability of EM38 to quantify and map the topographic relationship and variability of soil moisture content of the soil surface (0 -.15m). Soil cores were collected at 14 locations and used to determine soil particle size, bulk density, and available water content. Multiple EM38 surveys were conducted along transects of a rain-fed agricultural field and used to calibrate readings with volumetric water content. Data and maps developed with ArcGIS software will be presented of ECa survey measurements, water retention curves, particle size analyses, and bulk densities for soil cores collected. The goal of the study was to determine how soils – and associated moisture content – vary spatially and if this variability can be detected using EM38 sensor techniques.