How to Use Soil EC in Irrigation Management

Monitoring soil EC can be a valuable part of your toolkit for sustaining crop production in drought stricken or arid regions. Soil is an electrical conductor. The soil EC is a measure of how easily an electric current flows through the soil. Soil EC responds to the amount of salt in the soil as well as indicates the soil’s composition—the amount of sand, clay, organic matter, and water content.

Why is it important to monitor Soil EC?

Soil electrical conductivity, or soil EC, is a measure of the bulk soil ability to carry electric current, which is mostly dictated by the chemistry of and amount of soil water. The factors that affect soil EC include water content, porosity, soil texture and salinity level.

Salinity level influences the growth and development of a plant and fruit quality. A higher, or “bad”, EC is unacceptable for certain crops health and leads to lower crop production.

How soil salinity affects crops

Soil salinity that develops with irrigation in dry areas is a severe constraint for most crops. Salinity provokes an osmotic stress with adverse short-term effect on leaf expansion. High soil salinity reduces the plant’s ability to take up water, and the plant may even take up some of the salts which damages tissues and causes other issues, such as smaller fruit size, leaf burn or defoliation. In severe cases it can cause the plants to die.

Salt sensitive crops: Beans, carrot, okra, onion, strawberry, red clover, pear, apple, orange, plums, cherries, peaches, nectarines, apricots and almonds

Moderately sensitive crops: Broccoli, cauliflower, celery, eggplant, lettuce, muskmelon, pea, pepper, potato

If you have salt sensitive crops you want to be sure to monitor them continuously. Use wireless technology installed in the field to see early warning signs EC levels and challenges with water consumption.

What are ways to measure soil EC?

There are a number of ways to measure EC in the field, and farmers may find it useful to incorporate a number of methods since salinity may vary by soil layer or during the season in response to changes in temperature or drought. Research shows that soil EC changes as soil-water content changes, but the patterns of a soil EC map stay unchanged from year to year. Research shows that sandy soils with low organic matter have low EC, silts have medium EC, and clays have higher EC. A soil EC map is helpful because it identifies areas in a field that have different soil compositions which may benefit from different management strategies.

However, a soil EC map doesn’t provide seasonal or crop specific insights. In regions with an arid, semi-arid, or coastal climate, such as California, soil salinity varies by season. Late summer fog and ocean salt spray result in high EC values. Winter rains leach salt away, decreasing salinity, and in early spring salinity is at a low level. With much of the west in a prolonged drought, salinity levels are rising throughout the season and crops are impacted. Many of the most salt sensitive crops we mentioned are those that typically thrive in these regions, but with the drought and water restrictions, closely monitoring these crops is more important than ever.

AquaSpy’s approach to measuring soil EC

AquaSpy looks layer by layer into the soil and can see what’s occurring at the active root zone. This insight is critical for deep rooted trees which need to have water provided where and when it’s needed most.

Patented multi-sensor probes measure soil moisture, salinity, temperature and root zone activity independently at 4-inch intervals all the way down to 48 inches. Proprietary algorithms give yield-optimizing insights for ideal irrigation at critical growth stages such as bud development that impact the outcome of fruit and nut tree yields. The powerful AgSpy system provides analysis and actionable insights so growers can easily understand what is going on without having to visit the orchard or farm.