Understand controllers

Features - Strategies

A smart contractor trumps a 'smart' controller when it comes to irrigation systems' efficiency and effectiveness.

April 14, 2010

The design/build contractor has a unique opportunity to create something that people connect with on a deep, emotional level. Ask anyone about their favorite memory in a garden or landscape and the answer invariable touches deep-seated emotions and connections to family or a sense of place. Creating environments like this comes with the responsibility to ensure they are sustainable in every sense of the word – that the capital investment will give a return and that the landscape will thrive with the right level of input, whether that input is labor, water or product. 

Controller Focus
The component that has the greatest opportunity to ensure the success of the landscape is the irrigation system, particularly the controller. With an ever-increasing range of features available in irrigation controllers, what do you have to understand to get the most out of a controller?

For a contractor, the place to start is understanding plant water requirements. Understand the water needs of the plants, and arrange the plants into hydro zones, or groupings of plants with similar water requirements. The art is to mix the plants into esthetically pleasing combinations, and the science is to have those groupings require a similar amount of water.

Once the landscape design is worked out designing the irrigation system starts with the delivery system itself. The question to ask is, will developing the greatest amount and deepest roots for the plants in these hydro zones be best accomplished by spray irrigation or bubblers? If we do that well, the rest of what we look at and appreciate in the garden will follow! 

Choosing Hardware
After the delivery systems are designed, the choice of controller hardware is critical to the long-term success of the landscape. Many contractors have a “favorite” brand/model of controller they routinely install. This approach can miss the mark as far as delivering the best value over the long term. Criteria important for an installation contractor are ease of installation, availability, product familiarity and price. 

For an end user, there may be other specific requirements. When asked about what features or new technologies contribute most to managing more efficient systems John Moore, program manager of the California Landscape Contractor’s Association Water Management Certification Program says “… the more programs and more start times the better. My primary criteria are applying the correct amount of water to fill the root zone and avoid run-off. For example, a steep slope of clay soils might require numerous cycles of short duration to fill the root zone. Also, with multiple start time capability, I can incrementally increase water to match the longer days, and higher ambient temperatures of peak season plant water requirement.”

Greater levels of efficiency can be realized from a couple of fundamentally different approaches. One is labor-based, and one is technology-based. More labor – more time on site monitoring, taking core samples of the soil to observe how far water has penetrated and using that information to fine tune irrigation schedules – or the use of more sophisticated equipment that reduces the amount of labor input required.

Technology is Only a Tool
So-called “smart” controllers, once they are accurately calibrated, “self-adjust” their run times. Their scheduling is dynamic, not constrained by fixed program times.

“There are no short cuts. If you don’t do every step all the way through in setting up every irrigation zone, you will automate mismanagement,” Moore says. “Contractors have to understand that after installing the controller, it will take more than one return visit to accurately test and adjust the more complex controllers.”
A strong foundation of fundamentals is key to irrigation success.
So how do you ensure that you get the most out of what you’ve installed? Technology is only a tool; it is how it is applied that produces the result. The controllers themselves are no silver bullet. Installing the optimum gear can only provide the “potential” for efficiency.

The answer is what it has always been: behaviors based on greater understanding of the fundamentals. It starts with plant water requirement – plant water needs increase as the days get longer. Then soil: the water holding capacity and infiltration rate. Does the soil “accept” water readily, or does it run-off or puddle?

The next factor – and the one that has the most variability – is weather. A plant’s water need is dynamic; it changes throughout the year and mimics the length of the day. In general, the longer and hotter the day, the more water that plant needs. Correspondingly, after July as the days become shorter and cooler, the plants require less water.

Catch Tests
There is one more factor to understand. It is an eye-opening experience to perform a catch can test and see for yourself that the system you “eye-balled” as being pretty good, was in fact inefficient. The plain truth is the “state of the art” in irrigation distribution hardware, though improving, is not that good. Efficiency in distribution systems is heavily influenced by pressure and spacing, and most systems are not optimized in terms of their operating pressure and spacing.

This means you have to compensate for the lack of uniformity by adding additional duration to your irrigation schedules.

With the desire for more flexibility and features, manufacturers are challenged by what may appear to be mutually exclusive goals of keeping equipment simple and at the same time providing the complex features that remove labor from the equation of how efficiency is achieved. The current state of affairs is the market place is demanding irrigation to the bell curve of evpotranspiration.

There is no short cut around learning more about the fundamentals of the science of irrigation, as we further develop the art in creating memorable landscapes. Now we have viable options in deploying advanced hardware at a price point that is affordable. Make sure you are aware of the new products available, include a couple of trips back to the client’s site in your bid to properly calibrate the hardware and you will be amazed at the levels of efficiency that are possible.

The author is owner of Irrigation Essentials, a Web-based irrigation resource and consulting firm located in Mill Valley, Calif. Reach him via his Web site at www.irrigationessentials.com.