Irrigation Water in Agriculture
Agriculture holds a very important place in Turkey. The geographical and climatic features of our country make it highly suitable for farming. Although the share of agriculture in the economy has declined in recent years, it still remains of great importance.
In agricultural production, growers generally pay attention to soil structure. However, just as the characteristics of the soil are important, the quality criteria of irrigation water are equally critical. To achieve the highest quality and most efficient production, it is essential to understand the properties of the water used for irrigation. Not all water is suitable for irrigation; different crops require water with specific characteristics. For example, strawberries demand very delicate water, while date palms do not require such sensitivity. Therefore, every crop necessitates water of a particular quality.
For irrigation water, factors such as salinity, sodium content, bicarbonate, and boron ion levels are important.
Salinity
Salinity refers to the total salt content in soil or water. As soil salinity increases, plants attempt to release water to dilute the salts, which can hinder their growth.
| Class | Conductivity Value | Characteristic |
|---|---|---|
| C1 | 0 – 250 µS/cm | Low salinity; suitable for all plants and soils. |
| C2 | 250 – 750 µS/cm | Moderate salinity; salt-tolerant crops can be grown. |
| C3 | 750 – 2250 µS/cm | High salinity; usable in well-drained soils. |
| C4 | > 2250 µS/cm | Excessively saline; not suitable for irrigation. |
Sodium Adsorption Ratio (SAR)
The sodium content is expressed as the Sodium Adsorption Ratio (SAR), which measures the harmfulness of sodium in water.
| Class | SAR Value | Characteristic |
|---|---|---|
| S1 | 0 – 10 | Low |
| S2 | 10 – 18 | Medium |
| S3 | 18 – 26 | High |
| S4 | > 26 | Very high |
SAR Tolerance of Different Plants
| Tolerance | SAR Value | Plant | Symptoms |
|---|---|---|---|
| Very Sensitive | 2-8 | Deciduous fruit trees, citrus, avocado | Leaf scorch |
| Sensitive | 8-18 | Beans | Stunted growth |
| Moderately Tolerant | 18-46 | Alfalfa, oats, rice | Growth limitation due to soil structure |
| Tolerant | 46-102 | Wheat, barley, tomato, sugar beet | Growth inhibition due to poor soil structure |
Boron Level
Plants are very sensitive to boron toxicity. Even slight variations in boron levels in soil or water can cause toxicity.
| Class | Boron Concentration (mg/L) | Sensitive Plants | Moderately Sensitive Plants | Resistant Plants |
|---|---|---|---|---|
| I - Excellent | < 0.33 | < 0.67 | < 1.0 | |
| II - Good | 0.33-0.67 | 0.67-1.33 | 1.0-2.0 | |
| III - Usable | 0.67-1.0 | 1.33-2.0 | 2.0-3.0 | |
| IV - Questionable | 1.0-1.25 | 2.0-2.5 | 3.0-3.75 | |
| V - Unsuitable | > 1.25 | > 2.5 | > 3.75 |
Bicarbonate Ion Levels
In irrigation water, the level of sodium carbonate (Na₂CO₃) is particularly important:
- Less than 1.25 meq/L: Can be safely used for irrigation.
- Between 1.25 – 2.5 meq/L: Suitable for a limited number of crops.
- More than 2.5 meq/L: Definitely not usable for irrigation.
In agricultural applications, irrigation water is sourced from local wells, the sea, or rivers. For such water to be used for irrigation, it must pass through the most appropriate treatment system. At Kuzey Arıtma Engineering, our expert team designs and delivers turnkey water treatment systems tailored to your needs.