Fix Uneven Watering Before You Try Crop Steering

Topics: 

• The truth about pressure vs. flow
• Why your “perfect” crop steering protocol fails if irrigation is off
• What dripper pressure specs actually mean
• Best practices for line cleaning and dripper maintenance
• Whether automatic flush valves are worth the investment

Perfect for: growers, irrigation techs, facility managers, and anyone building or troubleshooting fertigation/irrigation systems in commercial agriculture.

Chapters:

24:30 – Sizing Pumps, Choosing Tubing, and Avoiding Supply Mistakes 
32:00 – Automatic Flush Valves: Worth It or Waste?

In new facilities, one of the most common mistakes is installing PVC piping first—whether schedule 40 or schedule 80—before planning the plant count and irrigation needs. Without designing the correct flow rates for the actual application, systems often fail to deliver proper performance once they’re turned on.

As irrigation manufacturers, we’re responsible for delivering the correct amount of water and nutrients to plants. Even though irrigation components may not be the most expensive part of a facility, they’re critical and carry the most liability when it comes to system performance.

A frequent issue is choosing incorrect components. For example, if you use a Leader pump without any pressure regulation at the bench, you’ll get uneven distribution. Drippers are designed to operate within specific pressure ranges, and exceeding those limits doesn’t make them “pop off,” but it does cause friction losses and uneven delivery.

It’s important to understand that pressure and flow are not the same thing. Many people confuse the two. Leader and DAB pumps, for instance, operate differently, and knowing how each works is essential for setting up the right pressure and flow for your benches.

Drippers themselves are designed with specific ranges. Some open at 9.5 psi, others at 17 psi, and both typically work up to 50 psi. The key is to keep them operating within their intended range to maintain consistency. Without regulation, you end up with “tallies and shorties”—plants at different points in the row receiving different volumes. Even with top-quality emitters, incorrect setup creates variability.

Adding simple components like regulators and gauges can solve many problems and make troubleshooting much easier. Without them, diagnosing uneven irrigation is possible but slower.

From a crop steering perspective, uniform delivery is non-negotiable. Even the best steering protocols are useless if plants aren’t getting equal volumes. Planning early with basic math—counting emitters per plant, calculating flow per zone, matching it against the pump curve—prevents most issues. Unfortunately, many facilities skip this step.

Rivulis Supertif emitters and similar components offer features like pressure compensation, minimum opening pressures, and non-drain options that can be valuable depending on the setup. But again, the priority is ensuring every plant gets the intended volume during each irrigation event.

On the fertigation side, clogged emitters are one of the most common complaints. Problems often come from poor pH adjustment, improper mixing, or neglecting line maintenance. Proper filtration and regular cleaning are critical. Whether using screen or disc filters, the important factor is monitoring pressure differential across the filter—typically a 3–7 psi drop indicates it’s time to clean.

For post-harvest line maintenance, the best practice is a two-step cleaning process. First, fill the lines with an acid or cleaning solution and let it sit with flush valves open, ensuring biofilm and debris are cleared from tubing. After flushing the lines, a second pass can run cleaning or sanitizing solution through the emitters themselves for direct service. Always finish with clean water before replanting.

Emitter design plays a role here as well. Pressure-compensated non-drain emitters (PCND) retain water in the lines, preventing air pockets and ensuring more consistent starts. They have specific opening and sealing pressures that dictate when they activate and shut off. Using higher opening pressure emitters can also improve line maintenance procedures.

Ultimately, irrigation should be designed around flow rates, not just pressure. Pumps, fittings, tubing diameters, and layouts all affect hydraulic performance. For example, 17mm tubing may only handle 5 gallons per minute at proper velocity, while 18mm or larger diameters allow more. Closed-loop layouts with flush valves and pressure gauges at the ends of benches improve uniformity and make maintenance easier.

Automatic flush valves are another option. They release water briefly at the start of an irrigation cycle, clearing debris before resealing. While they add extra water use that must be accounted for, many growers find them beneficial, especially in large facilities.

With good line maintenance and filtration, emitters can last many years, though replacement every 6–12 months is often recommended for reliability. Like LED lights, emitters may keep “working” but won’t necessarily deliver the correct output forever, especially under heavy use and chemical exposure.

In summary:

• Design irrigation around flow rate, not just pressure.

• Size pumps, tubing, and emitters to match plant count and zone demand.

• Use regulators, gauges, and flush valves for consistency and troubleshooting.

• Maintain filters properly and clean lines in a two-step process.

• Consider emitter replacement as part of regular maintenance.

These steps ensure even delivery, prevent clogging, and keep fertigation systems reliable over multiple crop cycles.