Not all water is suitable for irrigation

10 August 2022

All over Europe it is very dry. Many growers are forced to use irrigation. If you are going to use irrigation, keep an eye on the quality of the irrigation water. Groundwater can contain salts or iron. And that can be harmful. So have the water tested so you can weigh up the risks of drought stress and damage.

The quality of water can vary enormously. This includes both the chemical composition and the microbiological water quality. 

Chemical quality

With irrigation, the salt content of the water is particularly relevant. In addition to damaging the crop, irrigation with an increased salt content can also have adverse effects on the soil structure due to undesirable reactions with the clay particles.

A water analysis provides insight into the water quality. The basic examination determines the pH, EC, NH₄, K, Na, Ca, Mg, NO₃, Cl, S, HCO₃, P, Fe, Mn, Zn, B, Cu, Mo, Si and the hardness of the water. In addition, a more comprehensive examination for iron, Fe total examination is possible. This is useful when using pumped water. Pumped-up, anaerobic water may contain iron that reacts with the air and then forms iron oxides. These precipitates give rise to clogging of the irrigation system. 
In addition to an examination for salts or iron, it is also possible to have a residue analysis carried out in the water. This involves a broad analysis for the presence of residues of crop protection agents (incl. herbicides at low limits).

Biological quality

Not only the chemical quality of water is important. The microbiological quality also deserves attention. This is important to prevent the spread of fungi and bacteria and not to endanger the quality of the final product. Particularly in the case of surface water in the vicinity of sewage treatment plants, it is important to be alert to this. 
The 'GlobalGAP certification' includes standards that irrigation water must meet if it is used to irrigate field vegetables destined for the fresh market. Eurofins Agro can examine the presence of the bacteria E. coli, coliforms and enterococci.