The reaction to water soluble salts by soft fruit plants, varies among varieties, stages of growth and environmental conditions and most important, with the type of salts that they are exposed to.
Salinity of water is usually measured by Electrical Conductivity (EC): the more salts that are present in the water then the greater the ability to conduct electricity. There are European guidelines for most crops that show which EC level you would expect negative effects on plant growth and productivity. For example, Strawberry damage and yield reductions can occur at EC >1,000 uS/cm.
With Raspberries they can stand an EC of up to 4,000 uS/cm. but the lower the EC the better.
Coir matting which is commonly used as a substrate does concentrate up dissolved minerals and as such if the EC of the incoming water can be kept low, then this helps the growth potential.
New Farm Produce, Nr Lichfield, Staffs, part of the Berry Gardens group of growers, uses a borehole water supply to irrigate a number of different soft fruit crops including Strawberries. When tested, the water was found to be particularly high in Sulphate ions and so had to be treated before use. To do this they purchased, a Nano Filtration (NF) filter system.
The containerised system was installed in 2013 to reduce salt levels in the borehole water to very low concentrations, meaning that the water could then be blended with unfiltered water to get the optimum balance of nutrients for growth rate and fruit quality.
The blending of filtered and unfiltered water was easily controlled by the measurement of the blended water conductivity. The system was containerised for ease of installation and to give good weather protection.