Water Management And Treatment Strategies for Soilless Farming Success

1. Types of Soilless Cultivation and the Role of Water

The core of soilless cultivation is precise control of the plant growth environment. Proper water treatment not only improves crop yield and quality but also ensures efficient water use and long-term system sustainability. Soilless cultivation breaks away from the traditional dependence on soil by using nutrient solutions and growing substrates. In this process, the role of water fundamentally changes. It is no longer only an irrigation medium but becomes the main carrier that supports plant life.

In soilless cultivation systems, water is the “lifeline” of the entire operation. Water quality directly affects nutrient stability and plant health. If the water source contains excessive impurities, a series of problems may occur. Soilless cultivation requires water with low conductivity, low impurities, stable pH, and free of harmful ions and contaminants.

Possible issues include:

• Nutrient imbalance: High levels of Ca²⁺, Mg²⁺, or Na⁺ can disrupt nutrient solution balance and affect plant uptake.

• Irrigation blockage: Suspended solids or iron deposits may clog drip emitters and pipelines, reducing irrigation uniformity.

• Microbial contamination: Untreated water may contain pathogens that spread diseases through circulating systems.

Therefore, when selecting and treating water sources, key indicators such as ion concentration (especially Ca, Mg, Na), suspended solids, pH, and bicarbonate (HCO₃⁻) levels must be evaluated.

2. Core Water Treatment Technologies and Their Applications

Common water treatment technologies in soilless cultivation focus on removing impurities and pathogens to ensure clean irrigation water and smooth system operation.

Reverse Osmosis (RO)

RO is one of the most widely used and efficient purification technologies in soilless cultivation. It uses high pressure to push water through a semi-permeable membrane, removing most dissolved salts, heavy metals, bacteria, and viruses. It is especially important in areas with high-mineral groundwater or when growing salt-sensitive crops such as strawberries and blueberries. RO provides high-purity water, which ensures accurate nutrient formulation.

Electrodeionization (EDI)

EDI combines electrodialysis and ion exchange to continuously produce high-purity water without chemical regeneration. It is suitable for large-scale commercial production, high-value crops, medicinal plants, and research applications where the water quality requirements are extremely strict.

Ultraviolet (UV) Disinfection

In closed-loop irrigation systems, disinfecting the returned nutrient solution is essential to prevent pathogen spread. UV disinfection, especially in the 200–280 nm range, effectively destroys microbial DNA and prevents reproduction without altering the chemical composition of the water. It is a safe and efficient physical disinfection method.

3. Water Treatment and System Management Practices

Advanced water treatment must work together with scientific system management to achieve maximum results, especially in modern intelligent greenhouses.

Closed Irrigation System

These systems collect the excess nutrient solution drained by plants. After filtration (such as sand filters) and disinfection (such as UV with hydrogen peroxide), the solution is reused. This greatly reduces water and fertilizer consumption, minimizes discharge and pollution, and lowers production costs. A typical system includes a raw water tank, purified water tank, return nutrient tank, and disinfection units.

Nutrient Solution Management

Purified water is used to prepare nutrient solutions. Key parameters such as EC and pH must be strictly controlled.

• Example: Tomatoes require EC 1.5–2.0 mS/cm during fruiting.

• Sufficient dissolved oxygen must be maintained (approx. 7.63 mg/L at 30°C).

• Nutrient solutions must be protected from sunlight to prevent algae growth and kept at stable temperature.

When selecting a water treatment plan, it is important to consider the water source, crop type, production scale, budget, and environmental regulations.

• For small projects using rainwater or treated tap water, simple filtration and pH adjustment may be enough.

• For large-scale vegetable greenhouses using groundwater, a combination of RO for raw water + UV disinfection for return water is often required.

4. Types of Water Sources in Soilless Cultivation

The success of soilless cultivation highly depends on choosing the right water source. Below are the common source types and key considerations:

5. Key Water Quality Indicators

Regardless of the water source, the following parameters must be monitored:

Electrical Conductivity (EC)

• Target: ≤ 0.1 mS/cm, maximum 0.3 mS/cm

• High EC increases total salinity, causes root dehydration and slow growth.

pH

• Ideal range: 5.5–6.5

• Ensures optimal absorption of N, P, K.

• Deviations may cause precipitation of nutrients (e.g., Fe, Ca).

Total Dissolved Solids (TDS)

• Target: ≤ 100 mg/L

• High TDS increases substrate salinity and affects root growth.

Harmful Ions

• Chloride (Cl⁻): ≤ 50 mg/L

• Sodium (Na⁺): ≤ 20 mg/L

• Heavy metals must meet drinking-water standards to prevent crop accumulation.

Microbiological Indicators

• Total bacteria: ≤ 100 CFU/mL

• E. coli: must not be detected

• Excess microorganisms may cause root diseases, especially in hydroponics.

6. Recommendations for Water Source Treatment

• Tap Water: Let stand for 24 hours before use to release chlorine.

• Well Water: Conduct full water-quality testing; adjust Ca/Mg inputs if hardness is high.

• Rainwater: Settle and filter; do not use in areas with severe air pollution.

• River/Lake Water: Must be clarified and filtered. Avoid water affected by farmland runoff or industrial wastewater.

7. Water Quality Testing Frequency and Notes

Testing Frequency

• Water source testing: At least once per year

• Nutrient solution testing: At least once per month

• Routine monitoring: Test pH and EC at least once per week

Notes

• Ensure heavy metals (Hg, Cd, As, etc.) do not exceed limits

• Let tap water stand 24 hours to remove chlorine

• Suspended solids should be ≤10 mg/L

• Sodium chloride ≤200 mg/L (crop-dependent)

With regular testing and proper management, water quality can be maintained to support healthy plant growth, improving success rates and yields.

Conclusion

The use of water treatment technology enables soilless cultivation to precisely control the crop growth environment. This helps save water and fertilizer, reduce pesticide use, protect the environment from soil and groundwater contamination, and improve crop yield and quality. As water resources become increasingly limited and agriculture continues to modernize, efficient and environmentally friendly water treatment technologies will play an even more important role in the development of sustainable agriculture.

About Amanda & UMEK Team

Amanda & UMEK is a professional one-stop water treatment service provider. We deliver customized project design and engineering support based on local water-quality data, water-use requirements, and application needs. Our engineers develop solutions that meet budget and performance targets, covering:

• RO systems for drinking water

• Containerized water purification systems

• Seawater desalination for fishing vessels

• Bottled and barreled water filling lines

• Pharmaceutical purified water and WFI systems

• Food and beverage production water

• Boiler feed water

• Electronic-grade high-purity water

• Automatic softening systems

• And other industry-specific water treatment solutions

Contact Information:
Tel: +86 19331305749
Email: sales@cnumek.com / sales@amandawatertech.com
Website: www.amandawatertech.com / www.cnumek.com