Fertigation is 'dialed in' to deliver targeted nutrients

Issue Date: July 13, 2022

By Christine Souza

The irrigation technology known as fertigation has been around for some time. But with increased water-quality regulations by the state of California aimed at reducing nitrates in groundwater, farmers are adopting ways of targeting nutrients to plants using precise applications of fertilizers through irrigation systems.

"We really tried to get more dialed in as far as the timing in the irrigation set and getting the fertilizer into the water so that it ends up right in the root area and picked up by the tree and not leached down," said Stanislaus County farmer Daniel Bays, who grows almonds, apricots and walnuts.

He said the use of fertigation technology is growing as "more and more people have been making these improvements and starting to see the feasibility of it." He added, "Some of it, too, has come with development of irrigation technology as people have adopted more microirrigation."

Charles Burt, professor emeritus of irrigation, and chairman and founder of the Irrigation Training and Research Center at California Polytechnic State University, San Luis Obispo, explained that precision fertigation works through drip systems in which the flow rate and injection rate of fertilizers are continuous.

"It automatically tracks with the flow rate going into the system, so as you change sets, it automatically gives you more for less," Burt said. "There are multiple fertilizers at once, and these are remotely programmed and automatically injected simultaneously."

Plants need a lot of different amounts of fertilizers, which vary depending on the growing stage of the plant. To achieve uniform growth, Burt said, "you have to have uniform uptake and availability of nutrients."

If there is an imbalance or some spots that are weak with phosphorous, for example, he said, growers should add soil to those areas and can then apply evenly with fertigation.

Bays said once the application of nutrients is brought into balance for the crop, it then becomes easier to make adjustments during the growing season.

The tree-crop grower is working with the Madera-based Deerpoint Group Inc., which provides a service that includes the setup of automated fertilizer injector pumps known as a "white box."

"They'll come and recalibrate the pumps so that you are just putting on the dosage of fertilizer that you planned for that week," Bays said, adding that the dosage could include nitrogen, potassium, phosphorus or some other micronutrient.

Bays said the company takes tissue samples to see how the crop is responding to keep nutrients in balance for a particular field.

Deborah Miller, founder and president of the Deerpoint Group, which specializes in agricultural water treatment solutions, said the business 15 years ago added fertilizers, micronutrients and foliar products through the introduction of its white box.

"When we looked at the way fertilizers were applied, we said they're wasted, they don't get up into the plant efficiently, let's apply the same precision to the injection of fertilizers," Miller said. "We put a very complicated and complex feed system at the filter station that is automated to be run by computer and can inject any combination of fertilizers and micronutrients to any crop at a time.

"So we are maximizing uptake and minimizing the input of a particular fertilizer," she added. "It's the ultimate precision agriculture."

Geoff Klein, irrigation manager at Bullseye Farms in Woodland, said the farm adopted precision fertigation. Despite logistical challenges, he said he believes there is a savings benefit.

"If we have a 20% loss due to either water efficiency or fertilizer application efficiency, that 20% is a number, so you still save something," Klein said. "The idea of minimizing losses was the central focus. If we lose 20%, we have to buy 20% more fertilizer to actually hit the number that we should be putting into the trees."

With the rising cost of fertilizers, Klein said he believes more farmers may be more likely to change what they are doing to be more precise with applications and increasing efficiency.

"These (nitrate) regulations are coming no matter what, so the more we can improve and show that we are working to be better, it is going to be better in the long run," Klein said. "Saving fertilizer is saving money, and with the way agriculture is going right now, we're going to have to be much better businesspeople than we've ever been in the past."

The drought situation, Burt said, has many asking this question: If there is not enough water, how in the world are we going to have enough food? The answer, he said, has to do with efficiency.

"We have more than adequate research that demonstrates how, if a farmer does a lot of things right, including planting correctly and proper soil and proper scheduling of water, you increase the production per acre, per unit of water that's actually consumed," Burt said. "Fertigation is the key."

To learn more about precision fertigation, a free download of the ITRC manual on the topic can be obtained at itrc.org/books/fertigation.php.

(Christine Souza is an assistant editor for Ag Alert. She may be contacted at csouza@cfbf.com

Permission for use is granted, however, credit must be made to the California Farm Bureau Federation when reprinting this item.