Jeff Strom of Hilmar, Gary Crowell of Turlock, and Loren Lopes of Denair detailed their success during the recent 31st California Alfalfa and Forage Symposium at Modesto.

The trio are cooperators with Marsha Campbell Mathews, Stanislaus County farm advisor, who told the symposium: "Dairy lagoon water contains both ammonium and organic forms of nitrogen, way more potassium than you need, and usually plenty of phosphorous, all of which, when properly applied, can supply virtually all of the nutritional requirements of forage crops."

Until about five years ago, however, the obstacle was uncertainty about the exact nutrient content of applied lagoon water. The notoriously risky practice demanded an elusive balance. Applying too much invited crop damage or contamination of groundwater, while applying too little shorted the crop’s needs.

During the past few years, Mathews has been working with dairymen on three basic steps to capture the value of lagoon water, making it a fertilizer-resource operation — akin to applying anhydrous ammonia -- rather than an animal-waste discharge operation.

System basics

The basics of the system developed by the University of California Cooperative Extension are: first, a field quick-test to measure the two forms of nitrogen in the lagoon water before and during application; second, use of a flow meter to measure the amount of nutrient water applied, along with a valve to adjust the proportion of nutrient water injected into irrigation water; and third, keeping of complete records, either hard copy or computerized, to track the flow rates and amounts of nitrogen reaching the crop.

Those, plus calculations for the acreage, timing and amount of irrigation, amount of nitrogen needed by the crop, and other measurements, can take the guesswork out of using lagoon water.

Refinements, particularly to design of flow measurement and control for the specific site, are required for uniform distribution across the field and for accurate meter readings.

Strom, of Clauss Dairy Farms, was the first dairyman to work with Mathews on a demonstration in the UCCE Biologically Integrated Farming Systems project and has become a mentor for others.

To deliver the correct needs to his crops, Strom transfers nutrient water from three dairies each averaging 1,000 milking Jersey cows. Each dairy has three lagoons to settle solids before the nutrient water goes into a main lagoon. He uses the cleaner effluent for small corn and that having more organic matter for larger corn.

"We’ve been using only nutrient water to grow corn for the past two years for 350 acres," Strom said. "The results have been great, with almost $60 per acre savings in fertilizer. In February of 2001 we used nutrient water with well water to supply nutrients for winter forage. Our results were good, and we plan to repeat the process in 2002."

"Once this system is in place," he added, "management time is not more than it takes to order NH3." He recommended having a separate pump from the flush system to deliver nutrient water to the head of the water source for better mixing.

Crowell, whose family’s Bar Vee Dairy has 700 Holsteins with 550 replacement heifers on site, said they moved lagoon water "from the liability column to the asset column on our books and made proper use of it." He joined the project in 1999.

Calculations

He has a soil test done on each field to determine the amount of major elements needed for a specific yield goal. He then calculates the nutrient values in the water, the number of irrigations needed to deliver the desired amounts, and the rates of flow.

Although he concedes the system on 400 acres of corn does demand some intense management, Crowell said the rewards make it worthwhile. "Many fields were fertilized with this water only, with no commercial fertilizer, resulting in a production savings of about $100 per acre," he said, adding that he keeps close tabs on soil tests each fall and makes any adjustments indicated.

Crowell said he was impressed with the rapid pay-off of the system and with the fact that it puts him in a positive position with groundwater pollution issues in the future.

Lopes put his family’s 500-head Holstein dairy in the project in 2000. He said they previously used lagoon water and did not apply commercial fertilizers, but the practice "was flying blind" without any measurement of how much nutrients were applied.

Wants improvements

Although generally satisfied with the system, including two settling basins to trap solids prior to the flow into a lagoon, Lopes said he wants to make some improvements. Mainly, he needs more water during the winter when canal water is not available to dilute the nutrient water, and his fresh water pump doesn’t have sufficient capacity.

"Don’t think you are going to start this thing and have it work right-off-the-bat," he said. "You’ll have to learn your system, make modifications to it, see where the weak areas are, and make improvements."

While he doesn’t claim any dramatic savings in fertilizer costs, Lopes said that by being more careful with nutrient water, "We are avoiding salt and other problems and we will not have to buy as many amendments to correct them."

He advised interested dairymen to take a close look at other systems and size their own pumps, pipelines, and ponds adequately with room for expansion if that proves necessary.