The quality of irrigation water in gardening and sports fields, the parameters to be taken into account and the pH influence the quality of the plants and the soil.
Irrigation water in gardening
The best thing for the lawn and ornamental plants is that they have rainwater, preferably fine and that covers their needs. It would also wash its leaves and benefit its breathing.
But this does not always happen and less in the central and southern areas of the Peninsula.
The person in charge of the care of lawns and gardens is forced to compensate for the lack of rainwater with irrigation and one of the problems he has to solve is whether the water available is the most adequate.
Pure water has no salts, therefore it does not conduct electricity. Its components are oxygen and hydrogen in the proportion H 2 O. It is for this reason that to assess whether the water has salts, let's look at how it conducts electricity.
Irrigation water directly influences the health of the lawn and the attractiveness of ornamental plants. It is the main cause of the contribution of salts to the land, in addition to fertilizers.
Parameters that we must consider in irrigation water in gardening
We are going to develop in detail the parameters to be taken into account in gardening irrigation water:
Salinity
It is the amount of salts in the water. The most common salt is sodium chloride (NaCl)
We say that the water is fresh in rivers and lakes because the sodium chloride content is low
Salinity varies with the degree of evaporation. The water that evaporates does not contain salts and these accumulate in the ground.
- Salinity is measured with electrical conductivity in dS/m, (deciSiemens per meter) which is the capacity of water to conduct electricity per meter.
- Comparing the results of the conductivity of irrigation water with rainwater, which has a conductivity of 0.15 dS/m, is the way to see if it has a high salt content or not.
- Normal salinity in irrigation water is between 0.8 and 2.6. In seawater salinity ranges between 30 and 60dS/m.
- El exceso de sales induce en la planta un desequilibrio iónico y estrés con la correspondiente falta de agua. La La salinidad repercute directamente en:
- La germinación.
- El crecimiento.
- Altera la transpiración porque disminuye el crecimiento de las hojas.
- Se reducen los estomas de las hojas.
- Se retrasa la floración.
Sodicity
It is the amount of concentrated sodium with respect to calcium and magnesium and that we must analyze in the laboratory. It is measured in RAS or sodium absorption ratio by the ground.
Sodium tends to disperse the soil, especially clay particles. This causes the pores to become blocked and there is a greater risk of waterlogging. The soil becomes compact and lacks aeration, the plant has difficulties to absorb water and nutrients.
Sodium salts increase the pH.
The pH or acidity or alkalinity problem
pH is the measure of acidity or alkalinity that indicates the amount of hydrogen ions present in water.
Importance of pH in irrigation water in gardening
The pH of the water directly affects the lawn and plants in general.
- high pH : influences the absorption of nutrients because they become insoluble and are not easily absorbed. The plant suffers from a lack of nutrients and the soil accumulates excess salts.
The accumulation will be greater as the irrigation water of the garden is more acidic.
- A low pH : seriously damages the roots and therefore the absorption of the plant. High acid soils can make the plant toxic by accumulating aluminum.
How to lower the pH:
We can add nitric acid, phosphoric acid or sulfuric acid that acts much more slowly on the absorption of the plant. If the pH is acidic and we do not raise it, the plants are deficient in potassium and later in nitrogen.
To raise the pH:
Caustic soda or caustic potash is used. We must raise it with control, slightly acidic is better than more alkaline. If the pH is very alkaline, the plants have iron and zinc problems and long-term phosphorus problems.
The pH can be easily measured with strips of litmus paper. It is enough to compare it with the color sample to assess the acidity or alkalinity.
Problem of the accumulation of salts in the ground
When a garden or sports field is irrigated, even with perfect water, salts accumulate and tend to produce salinity in the ground due to accumulation, as we see in the following diagram.
If we add low-quality water to the already traditional problems due to continuous irrigation, the problem increases and the crops suffer alterations.
In times of heat, evaporation is greater and irrigation is also greater, the accumulation of salts increases.
If salinity is not controlled, the land is less and less productive. We must have a balance between the contribution of salts and those that the crop needs so that the soil does not accumulate them.
The accumulated salinity is sometimes proportional to the irrigation management. We must have a rigorous control of both the quality of the water and the quantity, which is what the crop needs.
The conductivity and humidity of the subsoil in the land can be measured with sensors Plantae, in real time and observe it on your mobile or tablet.
Sources
English 
Spanish