Drip irrigation can increase yields, allow more land under production when water resources are limited and save water and money. But you have to take care of the system if you want it to take care of you, according to Bill Cox, a consultant from Las Cruces, N.M.
Cox provided a consultant's perspective on drip irrigation at the National Alliance of Independent Crop Consultants annual meeting, in Tucson, Ariz., in January.
“It's a wonderful tool for the farmer,” said Cox, who first starting working with the technology in 1993. On one farmer's field in 1993, “our average red chili yields were about 16 tons per acre, which was extremely high at that time, and we were irrigating down the furrow. Based on the prices we received then, we normally expected to gross about $4,400 an acre.”
Heavy tillage was also the norm. “We ripped, disked and worked the beds with several 250-horsepower tractors.”
In addition, many farmers had to leave out part of their land each year simply because there wasn't enough water to go around.
Since drip was installed, average yields on that farm now exceed 40 tons and gross returns have more than doubled. “And we can farm all the land because we have the water. And we're down to one 250-horsepower tractor. When you figure out how much money drip costs you, look at the difference in yields per acre and how much more you can farm, drip doesn't cost you much at all.”
Drip benefits include the ability to water every field, every day, if needed. Fertilizer is also delivered to the crop through the system of underground tape. “We use a lot less nitrogen because we put it where it needs to be.”
Cox noted that after a drip irrigation, his growers can always get their spraying and harvesting equipment through the field.
He noted that a furrow irrigation was usually followed by a mulching trip with tractors to keep the soil from blowing. “With drip irrigation that doesn't happen much anymore.”
There is a steep learning curve with the technology, according to Cox. “We almost had to forget everything we thought we knew about farming. Each crop is different. Each drip system is different.”
One difference for Cox's customers is that large fields have to be micromanaged under drip. “With the amount of water we have available, we can usually manage a 20-acre drip plot at a time. So instead of a 100-acre field we have five, 20-acre plots now. Growers tend to plant something different on each one of those plots.”
Cox says drip irrigation “is the single-best thing that's happened to New Mexico agriculture since I started consulting 33 years ago. Here are some tips on making drip work:
“Drip will let you be a better farmer, but it will also make you be a better farmer. If you have a farmer wanting to dabble in drip who is a sloppy manager, who tends to let things slide, I'd steer clear of it.”
If you install a drip system, “you have to have GPS,” said Cox. “We bury the tape beneath the beds and farm the same beds year after year. It's harder than you think to harvest the same rows year after year. You move a little bit in the wrong direction with a piece of equipment and before you know it, you'll see a wet spot under the furrow.
“We have some harvest operations where we tend to pack the bed over the tape. We have to run spikes or chisels within 3 to 4 inches of the drip tape. With GPS you can do that. It's sad when you get to the end of the field, you pull the equipment out of the ground and you have all these black ribbons hanging behind it.”
If you have dirty water, especially water containing fine silt, purchase a sand media filter. “We have some that are 15 years old and still running.”
Design the system for the crop you're going to grow. “With cotton and corn, which are planted in the middle of the row, you can run the tape deeper. In situations where you're planting four to five rows on a bed, you want to wet the entire bed, so the tape needs to be shallower. The sandier the ground, the shallower the tape should be.”
Be careful where you put your first drip system. “Put it on good ground first. Be sure to get your ground right, no humps or holes.”
Maintain your drip system. “Gophers love to chew holes in drip tape. You have to flush the system, and chlorinate the system. Since 1993, a few of our growers have replaced their drip tape twice, others have replaced tape and the filters and others are still using the same system. It's all a function of how well you take care of it.”
Don't scrimp on drip tape. “The more money you spend on tape, the less time you'll spend plugging holes in it. One grower got a good deal on some lightweight drip tape on a brand new system. They put in the system, which was on some pretty rocky ground, then went in with a bed shaper. The activity pushed the rocks into the drip tape and punched holes in it. When they turned the water on, it looked like the dancing water show at Seaworld. It took them weeks to get the system running.”
Ideal spacing for emitters for us is about 12 inches, because we want to get the entire bed wet,” Cox said. “If you were going with cotton, you could probably go to 16 inches and perhaps go to a bigger block size. Your block size is determined by how much water you can put out.”