As California's historic drought persists, dairy farmers in the nation's top dairy producing state are increasingly looking to subsurface drip irrigation (SDI) technology as a solution for maximizing the water productivity and yield potential of their forage crops.

While the water-saving and productivity benefits of SDI are well documented, the challenges for dairy producers in utilizing naturally produced, nutrient-rich liquid manure as a forage crop fertilizer has limited wider adoption of SDI.

Recognizing the need to develop a drip irrigation solution that meets the needs of today¹s dairy farmers, Netafim USA and Sustainable Conservation teamed up in 2014 to develop an SDI solution that enables the consistent and reliable application of liquid manure as a nutrient-rich fertilizer.

“Historically, the drip irrigation industry has struggled with finding the right combination of filtration, mixture control and application technology that enables a dairy farmer to use an SDI system to apply naturally produced dairy wastewater as a fertilizer for their forage crops,” said Todd Rinkenberger, Netafim USA¹s Director of Sales, West Region. “Through our partnership with Sustainable Conservation and De Jager Farms, we have been able to make significant progress in developing the technology that not only increases water use efficiency and yield, but also provides dairy farmers with a reliable system for applying naturally produced dairy wastewater to forage crops.”

The innovative SDI system uses advanced filtration and proprietary methodology developed by Netafim that blends dairy wastewater with fresh water at precisely the right ratio by monitoring the electrical conductivity (EC) in the water as it passes by a sensor. As the EC of the water changes, the system controller makes real-time adjustments to the blending valves in order to keep the fertilizer mixture at a constant state as it is delivered to the plant¹s roots though drip irrigation tubing buried below the surface.

The groundbreaking technology was developed as part of a 2-year joint research study conducted at De Jager Farms in Chowchilla, CA. The study utilized two adjacent plots at De Jager Farms, both under a strip-till corn/no-till winter forage rotation. Each was equipped with a Netafim SDI system to deliver water and nutrients to the plant¹s root zone. The first plot received nutrients in the form of synthetic fertilizer, and the second plot received nutrient-rich dairy wastewater taken from the De Jager Farms dairy center. Throughout the project period, researchers from Sustainable Conservation gathered and analyzed data on crop performance, soil health, and water savings to better determine the system¹s effectiveness.

“We approached Netafim with the idea that drip irrigation could be used as a production tool to manage some of the regulatory issues that dairy farmers come up against in dealing with their wastewater,” said John Cardoza, Project Manager for Sustainable Conservation. “We are confident that we are well on our way to removing a major roadblock to the adoption of SDI by demonstrating that, with the right technology, SDI is a very efficient method for applying nutrient-rich water to forage crops.”

In addition to its ability to deliver nutrient-rich water to a crop, SDI has also shown to have a positive impact on the health of groundwater supply. “The use of SDI shows great promise as a system for reducing nitrate leaching, and the water-efficiency of the system results in farmers needing to pump less groundwater for irrigation purposes,” added Cardoza.

Analysis of the data is ongoing, but preliminary results are very positive according to De Jager Farm Manager, Nate Ray.

“It¹s a game changer for drip irrigation and it is a game changer for the way in which we apply our dairy wastewater,” said Ray. “We’ve reduced our overall water use on the test plot by 30% in one year and the yield per acre has improved by about 20%.”

But according to Ray, the numbers do not tell the whole story.

“When you walk through these fields you¹ll see a healthier, stronger plant when compared to our conventionally flood irrigated fields. We were surprised to see such a stark difference,” added Ray. “And, the digestibility was much better with the dairy wastewater fed silage than with the conventional.”

Netafim USA and Sustainable Conservation expect to begin making the technology available to dairy farmers beginning in 2016.