Uniformity, Accuracy Hallmarks of Drip Irrigation
Figuring out how to get water to thirsty crops has been an issue for farmers since the ancient Egyptians captured Nile floodwaters to soak their fields in the spring and the Romans brought water to their fields with aqueducts. The core objective of irrigation – delivering just enough water for the crop’s maximum growth, no more, no less – has not changed since then. If only the ancient civilizations had known about micro irrigation.
Uniform, targeted water delivery is the hallmark benefit of micro irrigation systems. Water is delivered directly to the root zone of the plants in quantities sufficient for the plant’s needs while minimizing water loss through evaporation or run-off. Because water is applied uniformly and regularly, stress due to soil moisture fluctuation is reduced or eliminated, leading to increases in crop quality and yield.
Bob Weimer, a partner with Weimer Farms in Atwater, California, has never looked back since installing a micro irrigation system on his farm in the late 1970s. “I don’t even like to think about what we were using before,” Weimer says. “I can remember growing up when we would go out at night and you’d start across a 40-acre peach orchard where you would have valves running and you would take a shovel and you would go across the field and change furrows in the middle of the night two or three times. I don’t even like to think about those days anymore.”
Drip irrigation is not maintenance free. “You still have a maintenance issue – you just change the things you do,” says Weimer. “It takes a different level of labor, more training, more technical use of people, but [drip] is effective.”
However, a properly designed and automated system will save a great deal of time, and even more importantly, deliver the water exactly where you want it.
“The one thing with drip irrigation, whether it be in row crops with drip tape or whether it would be in the orchards, is that it provides a uniformity of irrigation that we didn’t have with furrow irrigation or flood irrigation or even with sprinkler irrigation in many cases,” Weimer says. “You can also do variations with the drip system to reduce water in certain areas if you have heavier soils that are holding water.”
Weimer says being able to deliver water directly to the root zone conserves water and likes being able to target the amount of water very closely. The efficiency of a drip system can be up in the 90 percent range whereas the efficiency of flood or furrow irrigation might be at 50-60 percent, he says. Because the rate of water flow is less than with other systems, smaller water sources can be used for the same amount of acreage.
An additional benefit of a drip irrigation system is the ability to deliver fertilizer directly to the plant. There can be a cost savings, particularly with nitrogen fertilizers that are particularly subject to leaching, because less fertilizer is needed.
There are some harvest and labor advantages as well. “If you’re doing sprinkler or flood irrigation you have to shut your water off sooner than you would like to. We can keep our water going closer to the harvest period on the almonds before we shut it down,” Weimer says.
Drip irrigation, if properly designed, can operate well on even hilly land. Because smaller amounts of water are delivered at a slower rate than other types of irrigation systems, there is little or no run-off or puddling in low areas.
“Growers would not be going forward with drip irrigation and using this type of system if it wasn’t for the success in production,” Weimer says. “We’re not going to go back from where we are with our drip and micro-type irrigation systems. It’s here to stay and it’s only going to improve.”
Planning is Key to Success with Drip
Deciding which type of irrigation system is the best for your crop is one of your most important decisions as a grower. Water is, after all, the lifeblood of your plants. Without adequate water, nothing else – fertilizer, pest control, weed control or even soil – matters.
But what type of system is best? Sprinkler? Furrow? Drip? Each system has its own advantages and drawbacks. If you’ve been considering a drip system, it is probably because of its ability to provide water uniformly throughout the field without much waste. However, you may be concerned about the cost effectiveness or that it is difficult to install.
Bob Weimer, a partner at Weimer Farms in Atwater, California, began using drip irrigation in the 1970s. He uses drip tape on his sweet potatoes and above-ground tubing in his almond orchards. As a grower and as a former irrigation consultant he has advice for those considering converting to drip irrigation.
“It’s not real time consuming,” Weimer says. “You lay out your project with someone who understands pipe and water hydraulics. [They] create a system for you and you evaluate it from there. You need to do a lot of preliminary planning to make it work well, but once you’ve done that, the drip irrigation system is probably the least complicated to put in, versus a sprinkler system or some other type of system,” he says. “If you do your planning right, you’re going to minimize your complications.”
Weimer says factors to consider when designing a system are elevation changes, hill configurations, soil type, water quality, head losses, crop requirements, and most importantly, the quantity of water that is available. “You need to understand your peak demands during the summertime and whether you’re going to have adequate water to take care of the crop during that peak time period,” he says.
“You also need to know the quality of water that you’re dealing with, whether it is surface water where you’re going to have to do a high level of filtration, or whether it’s a ground water source such as out of a well, that might need only a minimum amount of filtration. You have to evaluate your water source very carefully.”
Weimer has never regretted his switch to drip irrigation. “What you’ll like about drip is the productivity. It’s a lot of freedom if you’re on an automatic system,” he says.
In 1990, when Weimer was working in the irrigation business, drip irrigation was rarely used in the San Joaquin Valley. He remembers installing it in a few fields to let growers see its benefits. “I started introducing the drip tape – and it was Ro-Drip at the time – which Rivulis has purchased. I brought [it in] and started installing it on a couple of fields and let it promote itself. Within ten years probably 90-95 percent of growers had drip irrigation on their sweet potatoes.”
Weimer is quick to say that drip irrigation is not maintenance free. “It took a different level of labor, more training, more technical use of people, but it was effective,” he says of their conversion. He cites rodents, tubing moving out of place due to temperature fluctuation and occasional chemical control of algae and bacteria in the lines as potential maintenance issues. But the cost is effective, he says, and stresses that it would not be successful if growers weren’t seeing improved quality of yield.
He is also happy with Rivulis products. “Rivulis is doing things correctly with their selection of product and companies they’re purchasing,” Weimer says. “We pick the products that are best for us and that’s what we like to install. We’ve had good service – products available when necessary, that’s important, to be able to get your product in a timely fashion – and to be able to get the service and help when you need it. We haven’t had any issues with that.”
The Almond Orchard’s Lifeblood
Choosing the right irrigation system for a block of almonds is not easy. It’s one of the more complicated, multi-faceted problems a grower faces, and to say there’s a lot riding on the decision is putting it mildly. It represents a significant investment; the future success of the orchard is dependent in large part on your decision. As veteran growers say, as a practical matter you only get one crack at planting an almond orchard, so you’d better do it right.
Who better then to ask for advice on irrigation than one of those veteran growers? Bob Weimer has been growing almonds – as well as peaches, sweet potatoes and walnuts – since before the widespread use of the modern drip and the micro-sprinkler systems in the late 1970s. Weimer, who farms in Atwater, CA, in the heart of the fertile San Joaquin Valley, advises young growers to look around. “You’ll see differences in certain areas. So look to the successful growers in your area, and see what they’re doing,” he says. “There’s lots of variation in almonds throughout the state.”
For example, while Weimer prefers drip irrigation because he believes it affords him the greatest control, you’ll see plenty of successful growers in Northern California using micro-sprinklers, because in colder regions they can be a lifesaver for frost protection. Successful growers can provide a lot of answers to complex irrigation questions, so study their techniques. “Why reinvent the wheel? You can make modifications or changes,” he says, “but you don’t need to reinvent the wheel.”
Don’t Stint On Quality
Once you’ve decided on a system, you have to decide where to source the equipment. Weimer says there a lot of good manufacturers, but he often gets his irrigation products from Rivulis Irrigation, mainly based on the old theory, if it ain’t broke, why fix it? “We’ve used a lot of products that Rivulis Irrigation has acquired, like Roberts (Irrigation) and Plastro (Irrigation Systems,) so we just continued on with it,” he says. “I’ve used Rivulis Irrigation products and I’ve had good results—that’s why I continue to use them.”
Weimer doesn’t cut corners on irrigation equipment because the most important lesson he’s learned through the years is that he has to be able to depend on his irrigation system absolutely.
“One thing we’ve found is you really can’t cheat on the amount of water you need to apply. You need to make sure there’s a cushion in your system so you can catch up if you get behind,” he says. “If the water profile gets way too low, you want to make sure your system can allow you to catch up.”
Reliability, then, is critical. That means a grower has to make sure that should he have any type of problem with his system, he can call for help. That’s another reason Weimer does a lot of business with Rivulis Irrigation. “The service has been good—like the product, very good. And the delivery times are very reliable, it’s been no issue,” he says. “They back up their products very well, as do some of the other companies we’ve worked with.”
White Is Just Right
Weimer also likes dealing with Rivulis Irrigation because they make a tremendous investment in R&D. The latest of the newer developments he has tried is white drip tubing, which his Rivulis Irrigation rep first showed him a couple of years ago. Weimer installed it when he planted his latest block of almonds, and so far, so great – the young block is really taking off.
White tubing should deflect heat more than the traditional black tubing, and being cooler it should slow the growth of algae which can clog emitters. “Also it appears we don’t get quite the expansion and retraction we get with the black tube,” he says. “When you put tube out that expands and contracts, the emitters begin to move around; one emitter can end up having no value whatsoever because it ends up so far from the tree.”
Weimer also appreciated the fact that though it is white, the tube has integrated construction. “It’s put together all at same time. It’s not like the white layer is added later,” he says. “We absolutely didn’t want double-walled tape or tubing. Other companies have come out with double-walled tubes for transfer lines, and we’ve found you can get separation. I was concerned that might be the case here, but no, you’re dealing with one solid wall.”