What is the relation between soil texture and its electric conductivity?

Question

What is the relation between soil texture and its electric conductivity?

Answer 1

Farmers practicing precision agriculture can now collect more detailed information about the spatial characteristics of their farming operations than ever before. 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 to precision farmers today. Soil EC measurement can provide more measurements in a shorter amount of time than traditional grid soil sampling.

Soil texture is a soil property used to describe the relative proportion of different grain sizes of mineral particles in a soil. Particles are grouped according to their size into what are called soil separates. These separates are typically named clay, silt, and sand. Soil texture classification is based on the fractions of soil separates present in a soil. The soil texture triangle is a diagram often used to figure out soil textures

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. This publication discusses: 1) How, 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; 2) Soil EC maps often visually correspond to patterns on yield maps and can help explain yield variation; and 3) Other uses of soil EC maps (Table 1), including 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.



More accurate soil property maps are needed to successfully implement precision farming decisions. Inadequate sampling density and the high cost of conventional soil sampling and analysis may prevent soil property segregation and classification. However, the use of soil EC measurements represents an alternative to intensive soil sampling and could both improve the resolution (increased sampling density) and reduce the cost of soil maps. Soil EC maps can be used to define management zones reflecting obvious trends in soil properties. Each zone can be sampled and treated independently.