The Silent Killer in Drip Irrigation

Poor filtration is the fastest way to clog emitters and reduce system life. Whether it’s media, screen, disc or hydrocyclone filters, every type needs a specific inspection and maintenance regime.

Even a small deviation in pressure differential across the filter can indicate a developing failure that may not be found until the crop suffers.

2. Operating Pressure

A small pressure change can dramatically affect emitter performance. Pressure changes can indicate emitter blockages or root intrusion if the pressure increases, or leaks if the pressure drops. The key is to measure the pressure compared to the original design specifications to spot variations early.

3. Flow Rate Monitoring

A drip system without flow monitoring is a system flying blind. A small reduction in flow may go unnoticed until yields fall. It is important to remember that a decreased flow means the plants are not getting the water they require as per the design. Conversely, an increase of flow is not a good thing, it often represents a leak.

4. Flushing

Even with clean water, silt and algae can accumulate in laterals and submains. If you’re not flushing regularly—with the right velocities—you’re building a clog that will be nearly impossible to remove later. Many growers flush too little, or with insufficient flow to be effective. Rivulis notes that when flushing, it is not just opening the drip irrigation line ends, it is about achieving sufficient water velocity to remove the debris. Submains require a flushing velocity of at least 0.5 m/s (1.5 ft/sec) and drip laterals at least 0.3 m/s (1 ft/ sec).

5. Chemical Treatment

Chemical treatment is necessary to avoid clogging of the drip lines by solids that precipitate and aggregate in the tubing, and organic matter that passes the filter and propagates inside the irrigation system. There are effectively two types of treatment– Acid treatment, used to dissolve mineral sediments, and oxidation Treatment (chlorine/peroxide), for oxidizing organic material, iron and manganese, prevention of algae formation, and elimination of sulfur bacteria.

Chemical treatment is very important, but it must be done right, and specific safety instructions must be adhered to. Furthermore, there are many considerations including acid types, chlorine vs hydrogen peroxide treatments, material sensitivity, and how to calculate concentrations and how much to inject. For this purpose, you will need to reference material on how to make these calculations, such as the Rivulis Knowledge Hub and Drip Guides (both available online at www.rivulis.com).

6. Leakage and Clogging Prevention

Pressure and flow measurement reveal problems after they have occurred. It is better is to undertake preventative measures to reduce the likelihood of leakage and clogging in the first place.

Part of your maintenance regime should also consider active management to prevent dripper root intrusion, insect damage, rodent damage, soil ingestion, and precipitation (when dissolved salts combine and become non-soluable).

7. Fertigation Management

Using fertilizers that are not truly soluble, incompatible fertilizers, and poor injection timing are leading causes of emitter damage.   

8. Pump and Water Source Maintenance

Your water source and your pump impact everything that follows. Open reservoirs require algae and sediment control. Pumps must be checked and maintained regularly.

9. Salinity Management

Salt doesn’t disappear, it builds up during each irrigation. Adding fertilizers can further increase salinity. Excess salt must be removed from the root zone before it increases to a level that seriously affects yield. Fortunately, there are many salt leaching techniques, ranging from consideration of where the drip laterals are placed, through to when and how long you irrigate for.