Precision ag can be based on EC measurement
Soil electrical conductivity (EC) is a measurement that correlates with soil properties that affect crop productivity, including soil texture, cation exchange capacity (CEC), drainage conditions, organic matter level, salinity, and subsoil characteristics.
With field verification, soil EC can be related to specific soil properties that affect crop yield, such as topsoil depth, pH, salt concentrations, and available water-holding capacity. Soil EC maps often visually correspond to patterns on yield maps and can help explain yield variation. Other uses of soil EC maps includ developing management zones, guiding directed soil sampling, assigning variable rates of crop inputs, fine tuning NRCS soil maps, improving the placement and interpretation of on-farm tests, salinity diagnosis and planning drainage remediation.
Now, more detailed information about the spatial characteristics of a farming operation can be achieved. In addition to yield, boundary and field attribute maps, new electronic, mechanical, and chemical sensors are being developed to measure and map many soil and plant properties. Soil EC is one of the simplest, least expensive soil measurements available for precision farming today. Soil EC measurement can provide more measurements in a shorter amount of time than traditional grid soil sampling.
The electrical conductivity of soils varies depending on the amount of moisture held by soil particles. Sands have a low conductivity, silts have a medium conductivity and clays have a high conductivity. Consequently, EC correlates strongly to soil particle size and texture.
Electrical conductivity (EC) is the ability of a material to transmit (conduct) an electrical current and is commonly expressed in units of milliSiemens per meter (mS/m). Soil EC measurements may also be reported in units of deciSiemens per meter (dS/m), which is equal to the reading in mS/m divided by 100.
MilliSiemens per meter (mS/M) is the standard units of measure of bulk soil conductivity. A Siemen is a measurement of a material’s conductance. The advantage of a standard unit of measure is that it makes the data quantitative.
Visual identification of soils can often determine color differences, but cannot attribute quantitative values to those colors. Soil EC maps showing values of “X” mS/meter enables a crop consultat or sales agronomist to identify and similarly manage other areas of the field with the same values.