For California growers like Nate Ray water efficiency is part of the process to improve farming systems.
Whether it’s “more crop per drop” as the new catch-phrase goes, or better use of dairy lagoon water to irrigate his corn and wheat rotation to feed 3,000 dairy cows, Ray continues to push towards getting more from less.
Ray manages the farming operations at DeJager Dairy in Chowchilla, Calif. His job may sound simple enough – feed the cows – but getting there is a team effort with his irrigation technology company, Netafim, and the non-profit group Sustainable Conservation.
While drip irrigation techniques – whether buried or laid flat across the surface – are gaining popularity on parched California farms, relatively new to the mix is the effort to move dairy lagoon water through the drip tape and emitters without plugging up the irrigation system.
By nature, dairy lagoon water is laden with solids. While this hasn’t presented much of a challenge in the past with producers using their lagoons to flood-irrigate crops, making the switch to drip systems has its obvious issues.
“The challenge is keeping the lines clean,” said Dennis Hannaford with Netafim USA.
DeJager Farms has found success in doing just that for the past three years, though folks like Hannaford admit “we need to tweak some things” to make the systems work even better.
What makes dairy lagoon water popular among farmers is the nitrogen it provides crops.
How it works
Corn grown for silage is irrigated with drip tape buried 12 inches deep on 60-inch centers. The corn is planted on 30-inch centers.
The system set up at DeJager Farms consists of several filters to keep the water flowing through the tiny emitter openings and keep irrigation lines from clogging.
According to Hannaford, water used on the dairy flush lanes moves manure liquids and solids towards the lagoon. An angled screen separates about 85 percent of the solids before they reach the lagoon.
From the lagoon water is lifted through a low-pressure line to a cluster of stand pipes. Well water is mixed 5:1 (more fresh water than lagoon water) with the nutrient-rich lagoon water. Flow meters gauge the rate water runs through the system on the fresh and lagoon water sides.
According to Ray, initial plans were to go with a 1:1 blend of lagoon water and fresh water but that was simply too thick to flow through the irrigation system.
Once the lagoon/fresh blend is made, the water moves through a double sand media filtration system. The double capacity works to handle the higher solids content of the lagoon water. There is an automatic back flush at rates that depend on the concentration of the water. The goal is to keep the system operating at the correct pressure.
The filtered irrigation water is then piped to the field where it goes into the buried drip lines and out the emitters. In this system the emitters have been engineered to have fewer turns where solids can accumulate.
Dan Rivers, a certified crop advisor and consultant on the project, says inspections of the drip tape and emitters reveal the drip tape is holding up to the nutrient-rich blends.
Periodic flows of Peracetic acid and fresh water through the drip lines are used to clean algae, bacteria and biofilm. Hannaford says efforts are made to allow good bacteria to work in their favor to help keep the lines clean.
The system has sensors to measure nitrogen concentration utilizing electrical conductivity (EC). This measures the nitrogen concentration in both lagoon and fresh water. A controller valve in the automated system blends lagoon and fresh water depending on the EC.
Nitrogen levels are sampled at several locations within the system, according to Hannaford. This helps determine proper nutrient applications and makes nitrogen reporting to state regulators easier.
DeJager Farms’ environmental consultants sample his irrigation water once a month to determine if they are on track with their nutrient management plan. They further use soil and plant tissue samples to make sure his nutrient applications are doing the job.
“The proportional valve adds a whole other dimension to the design of the system,” Ray said. “It took the guesswork out.”
DeJager’s sandy soil makes irrigating crops a challenge. Soil test show on some parts of the ranch the soil is 96 percent sand down to four feet.
Strip till conservation methods have greatly helped hold in soil moisture and produce other benefits, according to Ray.
“This has really been a nice picture of how conservation tillage works,” Ray said. “We’ve been doing strip till about seven years now.”
Adding the drip tape came after starting strip till conservation practices. Early on Ray said they installed the drip tape too shallow, thinking that the water would simply flow quickly down and away from the root zone. When that didn’t work as first thought they opted to bury the tape at 12 inches.
The results speak for themselves.
Previous corn yields under flooded furrows with conventional tillage practices were between 25 and 28 tons per acre for corn silage on more than 40 inches of irrigation. Through conservation tillage and the drip system Ray saves about a foot of water annually and is yielding on the high side of 30 tons per acre in his corn silage.
“It’s not that we’re just using less water, we can take that foot of water and farm something else with it elsewhere,” Ray said.
Ray grows winter wheat in rotation with the corn and is seeing a similar bump in yield with the wheat. Hannaford admits some striping can be seen in the wheat because of the wider drip tape spacing and how the water flows through the soil profile. This striping issue has been seen in subsurface drip applications with alfalfa as well.
DeJager Farms is aiming for combined yields in his winter wheat and corn silage at 50 tons per acre on an annual basis. Hannaford is optimistic that the target can easily be reached.
Ray believes that with regular maintenance, the drip systems in silage crops can last as long as drip systems in alfalfa. Ray’s strip-till practice allows the drip tape installed in fields where he rotates winter forage with corn silage to remain in place.
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