One man’s leftover is another man’s liquid soil amendment

Photo courtesy of Mary Thurn, Cornell University.

Turfgrass managers and lawn care professionals will soon have a new option when selecting organic fertilizers. According to recent research results, Converted Organics’ ( Liquid Soil Amendment can help reduce fungicide use.

USDA statistics estimate that more than 25 million tons of food are thrown away in the United States each year. That’s about 25 percent of the food in the country. A University of Arizona study puts that percentage as high as 50 percent. The U.S. EPA estimates disposal costs are approximately $1 billion annually. The United States isn’t alone; Japan and the United Kingdom each throw out about 30 to 40 percent of the food in their countries. Decaying food forms the greenhouse gas methane, a major environmental concern.

Frank Rossi, left, and associates take readings on turf plots.

Converted Organics, based in Boston, Mass., has developed a process to turn some of that discarded food into a product that is environmentally friendly and can help reduce landfill loads.

Trial results

Dr. Frank S. Rossi, turfgrass professor, Cornell University Department of Horticulture, conducted studies from 2005 to 2007 on liquid and granular forms of the Converted Organics product. Some of the studies conducted were one-year studies, others continued over the two-year period at the Cornell campus in Ithaca, N.Y.

Rossi said, “We do exploratory research trying to find the potential for products, exploring technologies. It’s particularly good when a company works with us up front like Converted Organics has, rather than trying to market their product, and then frantically trying to find out what they have.”

This flow chart illustrates the process of converting food waste to fertilizer.

The studies compared the fertilizer to other organic fertilizers using Cornell’s standard fertilizer program. “We applied it as both spray and granular in a manner that would be used on turf sites. We were just doing it on smaller plots,” Rossi said. “For the most part, the product behaved like any other organic fertilizer. It’s a slow release, because microbes have to break down material, but it catches up.”

Some advantages were found with the product. “We found that when diseases appeared, we had some interesting disease suppression.” Rossi noted that dollar spot and brown patch, both foliar diseases, were suppressed better by granular applications, while summer patch, a root disease, was suppressed better by the liquid application. “They were suppressed by 30 to 40 percent,” he said.

Rossi noted that the most significant advantage was that use of the product reduced fungicide applications. “We found that when we incorporated these applications with our fungicide program, we were able to reduce fungicide applications by about half,” he said.

Turfgrass quality and soil ecosystems

Turfgrass managers want healthy turf. Healthy turf, like healthy humans, needs a diverse source of nutrients. According to Dr. William Torello, consultant to Converted Organics, food waste has a high degree of diversity. Torello, a retired University of Massachusetts turfgrass professor, noted that the product contains an array of organic materials. He said that organic diversity is a key element in developing diverse soil and microbial activities that directly affect disease suppression.

Additionally, Torello said that processed food waste is more acceptable to the public than treated sewage sludge, a common source of organic products.

Torello cited the cultural stresses that turfgrass ecosystems are subjected to through mowing, compaction, irrigation and overapplication of pesticides. “Anything we can do to promote soil microbial diversity, as well as population and activities, will quickly pay off in a much healthier turfgrass ecosystem and overall quality,” he said.

Integrating current technology

Converting food waste from the scraps left on diners’ plates to organic fertilizer pellets and liquid for turf treatment isn’t a simple operation. While the process is somewhat like a super backyard compost operation, the steps and techniques are quite complex.

Ed Gildea, president and CEO of Converted Organics, said, “We are using a technology that has been used for many years in connection with treating sewage and wastewater before they enter surface water or other disposal.” The technology, enhanced autogenous thermophilic aerobic digestion, is used in Europe, Canada and the United States with only slight differences. The process introduces oxygen and heat into a closed tank to accelerate the digestion.

While the technology has been used extensively, Gildea said, “Our business model is the first of its kind.” The company has contracts with food waste haulers for enough waste to produce about 80 percent of the capacity of a plant currently under construction in Woodbridge, N. J., just outside New York City.

“Plants need to be near high food waste producers,” Gildea said. Urban areas with high population concentrations produce high amounts of food waste. The 60,000-square-foot facility is expected to begin production in April or May. “It’s all contained inside, since odors will be present,” Gildea said.

The process

The facility includes a large, open area called a tip floor. Haulers will tip loads onto the floor, where hand sorting will be done to remove inorganic material. The waste will then be moved on a conveyer belt to the macerator, a large tank. The 30,000-gallon tank is similar to tanks used in pulp mills. The food waste will be pulverized with the addition of water or other liquid.

During pulverization, light, inorganic material, such as plastic, will come to the top of the mix, where it will be skimmed off. Heavy, inorganic material, such as metal, will drop to the bottom, where it will be removed. The slurry mix will initially be about 9 percent solids and 91 percent liquid, and it will be pumped to the digester, a 140,000-gallon tank, where digesting takes place. The macerator and digester tanks are manufactured by RECO Constructors, Richmond, Va.

Heat, air and microbes are added during the digesting process. Microbes are added in a process similar to making sourdough bread, where a small batch of previous product is added to the mix. After digestion, the product moves to a rotary press where solids and liquids are separated.

The solids will be enriched with feather meal, a waste product from fowls that is traded as a commodity. The solids will then move to a pin mill, where the product will be formed into a small, round nugget about the size of a BB. The liquid will go to an evaporator, where it will be condensed for shipment. Current plans call for the product to be shipped in 210-gallon containers for commercial users and 5-gallon containers for small businesses and home use. The liquid will be produced for a 50-to-1 dilution. Solids will be packaged in 20 and 40-pound bags for use on home lawns and in 50-pound bags for golf course greens, fairways and roughs and other large turf sites.

Rich Aleo, vice president of marketing, said, “Opportunities are out there with the organic category exploding. The liquid can be added to fertigation, and the solids can be used in both broadcast and home spreaders.” Aleo noted that solids will also be produced for use on fruits and vegetables and will be enriched with potassium, potash and a small amount of feather meal. The liquid can be customized with the addition of different nutrients as the market develops. Packaging of both liquid and solid product may be modified to meet market needs.

Nancy Riggs is a freelance writer and frequent contributor to Turf. She resides in Mt. Zion, Ill.