Sustainable Conservation Project Director John Cardoza (left) with De Jager Farms CEO Nate Ray (right) with feed corn grown using the SDI-E system. (Photo: Paolo Vescia)

With a Conservation Innovation Grant, dairy effluent technology expands to almonds.

By Natalie Willis, Reporter, Valley Ag Voice

In 2014, mounting concerns around California’s severe drought and increasing regulatory pressures gave rise to a collaborative effort between Sustainable Conservation, Netafim USA, and De Jager Farms to revolutionize water efficiency and nutrient management for dairy farms in the Central Valley.

Nate Ray, CEO of De Jager Farms, spearheaded this effort, proposing that his operation’s lagoon water be utilized through drip tape to sustain feed crops in place of traditional flood irrigation.

Ray began experimenting with the Subsurface Drip Irrigation for Dairy Effluent system shortly after the passage of the Sustainable Groundwater Management Act.

“SGMA, the framework of it, was in its infancy stages at that point that nobody really knew — we didn’t know if we were going to get our wells metered, nobody knew what the rules were,” Ray said. “We just knew that, to be good stewards of the land, to be sustainable for future generations, we were going to have to reduce the amount of water that we pumped out of the ground ourselves…but we understand the cyclical nature of how the weather patterns are, and we know that there is a time that we have to tap into that resource below us. As much as we can preserve that and not overdraft, that is our main goal.”

Ray brought in Sustainable Conservation and Netafim USA to enhance his ability to test the system. Since then, the SDI-E system has been used successfully on dairy farms to fertilize non-human consumables, eliminating the need for synthetic fertilizers and maximizing crop yields. The system saves over 2.3 billion gallons of water and 2.4 million pounds of nitrogen pollution annually across 4,432 acres of feed crops in California, according to a press release from Sustainable Conservation.

The SDI-E system continues to expand upon its efficiencies and recently secured a Conservation Innovation Grant from the National Resources Conservation Service for a first-of-its-kind pilot project at De Jager Farms where it will be adapted to irrigate and fertilize almonds.

IRRIGATING DAIRY EFFLUENT

Traditionally, dairies flood irrigate feed crops from their lagoons because drip systems are not equipped to handle organic effluent, requiring producers to utilize synthetic fertilizers.

According to Domonic Rossini, Western Agronomy Leader at Netafim USA, the SDI-E system blends fresh water and manure water at a targeted electro-conductivity which measures the salts in the water as most nitrogen fertilizers have a salt base.

“The system automatically senses what’s coming in and going out…so, as the lagoon water will go up and down, the valve will actually open and close to add the proper amount of lagoon water to freshwater ratio, so it gets the target that you’re shooting for,” Rossini said. 

Through Netafim’s irrigation technology, the system can be set to reach a target based on prior water samples measuring the amount of nitrogen and other components present in lagoon water. This precise blending is crucial, as it prevents the introduction of excessive salts and nitrogen, which can be harmful to the crops.

Then, the nutrient-rich water undergoes double filtration to remove solids before being distributed through a standard buried drip irrigation system.

“So again, kind of simplistically, it’s to reduce your input costs and to reduce your need on natural resources with maximizing production. So that’s kind of where the end goal is on all of it,” Rossini said.

The unique feature of the SDI-E system, Rossini explained, is its sub-surface utilization of manure which has reduced greenhouse gases by 70-80%.

“It’s another steward that helps us not only use these natural resources but also reduce greenhouse gases, which if you look at the dairy industry, they are a target for a lot of things, especially greenhouse gases and detrimental to the water table because you have nitrogen that goes down past,” Rossini said. “So, by applying it to when the plant needs it, [and] how it needs it, it uses it, and it doesn’t go down further. And applying it subsurface, you don’t have the greenhouse gas issue.”

The system’s potential is now being explored for human-consumable crops. With the support of the CIG grant, research and experimentation will begin at De Jager Farms to adapt the technology for almond cultivation, marking the first step toward broader applications.

PILOT PROJECT

As the project moves toward testing on human consumables, John Cardoza, project director at Sustainable Conservation, explained that food safety remains a top priority. With the official green light from the California Department of Agriculture and the Department of Public Health, the project will implement rigorous safety protocols to ensure compliance with food safety standards during the testing phase.

“What we’re going to be doing to make sure it’s safe during this project over the next couple of years is, we’re going to be doing a lot of testing,” Cardoza said. “So, we’re taking a lot of tests from the soils, from the lagoon water, from the freshwater, from the tissues of the tree, and we’re going to monitor it.”

Cardoza explained that tests will cover every aspect touched on by the SDI-E system, including the soils, lagoon water, freshwater, and tree tissues from the almond trees. The project will test whether the SDI-E system keeps water and bacteria below the soil’s surface or if they rise to the surface. This will involve monitoring the concentration of bacteria, testing the nuts at harvest, and observing if any bacteria make it onto the shells or nuts.

The pilot project is expected to run for three years, working with 2025 and 2026 cropping years before a final analysis and reporting in 2027, Cardoza explained.

According to Ray, the SDI-E system was created with dairy producers in mind to fertilize and irrigate forage crops. However, several dairy operations have diversified into other crops, with fields for human consumption often adjacent to SDI-E systems already in place.  

“And so, it kind of went hand in hand that, if we can take the same technology that we’ve been utilizing on our forage crops, taking advantage of the valuable resource that we have being the effluent and all the nutrients that are contained in it, apply that to these other crops that we grow, and see those increased savings from the fertilizer standpoint, and start to move away from the synthetics that we have to apply on our other crops,” Ray said.

The end goal is for farmers to utilize natural resources and maximize production with limiting inputs. Typically, Rossini explained, converting from a flood system to a drip system results in a 25% gain in production, and water consumption is reduced by roughly an acre-foot. Further, with sub-surface drip irrigation, water is not lost to the atmosphere due to heat and runoff.

“You know, farming is being restricted to less and less land…so if we can maximize what we have, it allows us to produce so we can keep feeding this growing population with safe food,” Rossini said.

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