IMKO´s TRIME TDR-probes can now report soil EC as standard simultaneously with soil moisture content percentage. A manual conversion based on researched curves for different soil types enables the user to derive a soil EC expressed in mg/l TDS (total dissolved salts).
For agricultural and horticultural soils, the measurement of Electrical Conductivity is an immensely important measurement. Electrical Conductivity measures the amount of total dissolved salts (TDS) or total dissolved ions in water. To complicate matters, some ions such as Sodium and Chloride will contribute more to EC than others such as Phosphorus and Potassium.
Plants require nutrients such as Nitrogen, Phosphorus, Potassium, Magnesium in large quantities hence they are called major nutrients and also smaller amounts of elements such as Iron, Manganese , Molybdenum and these are called micro nutrients or sometimes referred to as trace metals. Fertilisers are supplied to plants as compounds for example Ammonium Nitrate which supplies Nitrogen in the form of Nitrate or Ammonium. Micro-organisms will break down these compounds so they are more readily available for uptake by the plants. Levels of some ions such as Chlorides are less desirable and in great quantities can be harmful to plant growth. The quantity of ions or salts in a soil is of huge importance. Too much or too few nutrients will create a restriction in plant growth.
IMKO has studied the subject in detail and has come up with a breakthrough. By using coated rods and measuring over the length of the probes, all TRIME probes can now accurately report what IMKO calls ECTRIME. This measurement takes account of soil moisture and conductivity by volume. Because soil moisture is so important in the calculation of EC, all different TRIME probes now incorporate TDR calibration curves for a selection of soils. Special graphs have been constructed so that the user can convert the ECTRIME reading to grams/litre of dissolved salt. So far curves are available for sandy and loam soils and it is intended to produce a handful of curves to cover most situations. At this moment in time, conversion of ECTRIME to mg/l TDS is done manually.
IMKO hopes that this breakthrough whereby a TDR instrument can be used to derive a true soil EC measurement will become the new standard for soil fertilisation analyses.