Soil Electrical Conductivity
Relationship to Soil Function
Soil EC does not directly affect plant growth but has been used as an indirect indicator of the amount of nutrients available for plant uptake and salinity levels. EC has been used as a surrogate measure of salt concentration, organic matter, cation-exchange capacity, soil texture, soil thickness, nutrients (e.g., nitrate), water-holding capacity, and drainage conditions. In site-specific management and high-intensity soil surveys, EC is used to partition units of management, differentiate soil types, and predict soil fertility and crop yields. For example, farmers can use EC maps to apply different management strategies (e.g., N fertilizers) to sections of a field that have different types of soil. In some management units, high EC has been associated with high levels of nitrate and other selected soil nutrients (P, K, Ca, Mg, Mn, Zn, and Cu). Most microorganisms are sensitive to salt (high EC). Actinomycetes and fungi are less sensitive than bacteria, except for halophyte (salt-tolerant) bacteria. Microbial processes, including respiration and nitrification, decline as EC increases (table 2).
Problems with Poor Soil EC Levels
High EC can serve as an indication of salinity (EC > 4 dS/m) problems, which impede crop growth (inability to absorb water even when present) and microbial activity (tables 2 and 3). Soils with high EC resulting from a high concentration of sodium generally have poor structure and drainage, and sodium becomes toxic to plants.
Improving Soil EC
Effective irrigation practices, which wash soluble salts out of soil and beyond the rooting depth, can decrease EC. Excessive irrigation and waterlogging should be avoided since a rising water table may bring soluble salts into the root zone. In arid climates, plant residue and mulch help soils to remain wetter and thus allow seasonal precipitation and irrigation to be more effective in leaching salts from the surface. To avoid the adverse effects of high EC (salinity) in irrigation water, the leaching requirement must be calculated for each crop. Leaching requirement is the fraction of water needed to flush excessive salt below the root zone, that is, the amount of additional water required to maintain a target salinity level. Adding organic matter, such as manure and compost, increases EC by adding cations and anions and improving the water-holding capacity. In some cases, a combination of irrigation and drainage is necessary to lower salt concentration and EC. An EC water (ECw) ≤ 0.75 dS/m is considered good for irrigation water. Beyond this value, leaching or a combination of leaching and drainage will be necessary if the water is used.
This Page Was Created Utilizing Text And Images From These Sources:
Soil Electrical Conductivity, Soil Quality Indicators Fact Sheet- USDA Natural Resources Conservation
2023 Soil Health School Registration Open!
The 2023 Soil Health School will be held August 28-30 on the farms of Anthony Bly and Bruce Carlson near Garretson, SD! There will be classroom sessions, field excercises, discussion panels, and opportunities to network with researchers, industry professionals, and experienced producers who can help you on your soil health journey! Class size is limited, so learn more and register today!
News & Events
Long-term research reveals advantages of diverse crop rotations
By Stan Wise PIERRE, SD – It can take time for scientists to build new knowledge of biological processes, especially when those processes play out over the course of years. Researchers with the U.S. Department of Agriculture-Agricultural Research Service North Central...
‘Park the chisel’: First step toward soil health can be simple
By Stan Wise PIERRE, SD – The benefits of improved soil health for agricultural producers and gardeners are numerous and valuable – reduced input costs, improved profitability, drought and flood resilience, reduced erosion, improved water quality, increased wildlife...
Saline Soil Management: More Money With Fewer Crop Acres
By Stan Wise PIERRE, SD – Salinity areas. Trouble spots. White deserts. Regardless of what they’re called, saline soils are a problem for South Dakota. White, salty areas where nothing grows are a common sight in fields across the state. “The amount of salinity that's...