irrigation water: water solutions and treatment for irrigation water that optimise crop growth and plant health

water treatment for irrigation: maximise your investment


Industrial energy efficient reverse osmosis desalination system with SMART PLC control
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Need some advice? We’re here to help.

1. Water treatment for irrigation: maximise your crop and investment

Watercore engineers work with farmers to provide the best solutions and treatment for irrigation water. Water quality is often not good enough for irrigation what has an impact on the farm productivity. Normal problems linked to poor water quality are low plant growth and blocked irrigation pipes.

Farm water comes from many different sources with very variable quality. Water sources include dams, bores, wells, rivers, town water, channels and recycled water. 

Problems with ground water quality may have a chemical or physical basis. High acidity, alkalinity or elevated water salinity are common chemical problems. Frequent physical problems are high concentration of particles in suspension (turbidity) or algae.
Watercore have a range of solutions that cover different irrigation water problems and help obtaining the optimal water quality to your farm.

2. Main quality issues in irrigation water and how to solve them

FactorTypical ThresholdEffect in Plant and EquipmentSolution
Chloride or Sodium in WaterCl < 175 mg/L
Na < 115 mg/L
Leaf injury/burn, defoliation & crop yield reduction. Development of poor soil physical conditions. RO Desalination
Water Salinitycrop dependentLimits the root ability to absorb water. Crop reduction. RO Desalination
High / Low PH6 < PH < 7.5Nutrients imbalance, corrosion in pipes, carbonate scaling. Reduction in pesticide efficiencyPH controllers
Iron in water> 0.2 mg/L may cause clogging of irrigation systems.

> 5 mg/L may produce light-brown spotting on plants
Light-brown spotting on plants. Discolour leaves. Poor transpiration and photosynthesis. Reduced access to phosphorus (essential nutrient)Iron & Manganese Filters
Manganese in waterMn < 0.2 mg/LAt high concentrations Manganese
is highly toxic to plants, especially to root growth.
Iron & Manganese Filters
Water HardnessHardness < 150 mg/l of CaCO3Unwanted precipitates may cause damage to plants, soil and equipment.Water Softeners
Turbidity in waterClogged nozzles/pipes. Bacteria.Sediment and Turbidity Filers
Pathogens (viruses, bacteria & fungi)Crop damageWater Disinfection

3. Learn more about solutions and treatment for irrigation water

Plant tolerance to salinity will define the ability of plants to survive and produce prosperous yields under different irrigation conditions. Plants respond to water salinity in the root zone from two main perspectives:

  1. Water salinity limits the root ability to absorb water. When salinity is too high plants wilt and begin to die.
  2. High concentrations of specific ions, particularly sodium and chloride, has a toxic effect on plants.

The point at which this happens depends on the type of plant, some crops are more tolerant to salts than others. Tolerance to water salinity is also lower during germination and seedling.

It is important to highlight though that an extremely low salinity in irrigation water can have adverse consequences to the soil stability, leading to soil leaching (solution and loss of water-soluble plant nutrients from the soil).

Typical salinity ratings for irrigation water based on electrical conductivity are :

EC (dS/m)Plant suitabilityExamples
0.65Sensitive cropsBean, Strawberry, Raspberry, Carrot, Eggplant
0.65−1.3Moderately sensitive cropsPeanut, Sugarcane, Avocado, Apple, Citrus fruit, Grape
1.3−2.7Moderately tolerant cropsRice, Fig, Olive, Cucumber,Spinach, Tomato
2.7−4.5Tolerant cropsZucchini, Sunflower, Wheat
4.5−8.1Very tolerant cropsCotton, Barley
>8.1Not suitable for irrigation

Our adaptive RO units can adjust the conductivity in your irrigation water to match your crop limit. Oposite to standard RO units, this technology reduces the overall water use and rejection.

The chlorides of sodium, potassium, calcium and magnesium are highly soluble in water.
Chloride behaves similarly to sodium with similar foliar symptoms and toxicity at high concentrations.

A high proportion of sodium in soil (sodicity) is also a condition that degrades soil properties by making the it more erodible and restricting water entry.

Yield declines attributed to chloride and sodium levels in waters are also closely related to an osmotic effect, hence threshold values for salinity should be used as a guideline.

Although hardness does not have a direct impact on the plants, it does on the soil and irrigation equipment.
Many dissolved ions like Iron and Manganese contribute to the total water hardness,  however it is usually the presence of Calcium and Magnesium what accounts for water hardness.
Water hardness higher than 150 mg/l of CaCO3 is usually unacceptable for most farm uses.
The PH of water represents how acidic or alkaline it is. It can affect plant growth, irrigation equipment, pesticide efficiency and potability.
In general, pH for irrigation water is acceptable for values between 6 and 7.5 as it will:
  • maintain the nutrient balance
  • prevent scale formation
  • allow adequate chlorine disinfection
When the PH is higher than 8, the bicarbonate in water will start transforming into  carbonates. This can cause calcium and magnesium to precipitate affecting plant growth. These precipitates are also responsible for irrigation pipe clogging.
A pH higher than 7.5 will also reduce the effectiveness of chlorine disinfection. This is important in case of drinking water.
Acidic water will also affect the plant growth and will corrode metal pipes and water tanks.
In general a pH below 6.0 or above 8.5 will reduce the effectiveness of pesticides.
How we can help:
Our PH adjustment system monitors and controls the water PH by means of in-line acid/base dosing.

Sand, silt, clay and organic matter are the most common particulates carried by the water in the form of suspended solids.  This is most common at high flow rates in surface waters. Groundwater tends to contain limited organic matter and solids in suspension.

Chemical precipitation of  calcium and magnesium carbonates and sulfates or oxidised iron is another form of suspended solids commonly related to groundwaters.

Filtration is the most effective method of removal of particulate material from the water source.

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Download our free e-book to learn everything you need to know about water salinity limit for each crop. The e-book includes salinity limits for more than 100 fruits, grains, vegetables, pastures and ornamental plants!

Download our free e-book to learn everything you need to know about water salinity limit for each crop. The e-book includes salinity limits for more than 100 fruits, grains, vegetables, pastures and ornamental plants!