Spring gardeners, lawn manicurists and nursery folk of all varieties on the hunt for cheap fertilizer this planting season need look no farther than the wastewater treatment facility in Greenfield, Ind., where there is an ample supply that will not run out anytime soon.

Stored in two open-air storage barns, numerous 12-foot-high piles of "Class A" biosolids processed from the treatment plant stand ready to be applied to area lawns, gardens and farms instead of being transported to the landfill.

The mounds look like little more than rich, dark soil. There are no flies and only the slight aroma of ammonia floats in the air.

The city has been producing the fertilizer since 2004 and has been supplying it primarily to farmers and some residential takers as well.

The biosolid is initially pumped from the plant’s sludge holding tanks, where aerobic and anaerobic micro-organisms start the treatment processes. The liquid material is further treated and then piped through mixers and presses that add a polymer to give the substance cohesiveness and squeeze out the water.

Fly ash, a highly alkaline residue from coal-fired power plants that has a high capacity for water absorption, is added to increase the pH level and further solidify the material, and it is then heaped under the storage barns where the sun bakes it to 150 degrees for three days to finally eradicate any remaining pathogens and increase pH to the desired level.
Every batch is tested by a third-party, state-approved laboratory to make sure the fertilizer conforms to state and federal health guidelines.

The city charges $2 per cubic yard for the first biosolid yard and $1 for each additional yard. Quantities of 25 cubic yards or more, roughly a dump truck full, are free if you bring your own truck.

The city produces between 1,200 and 1,500 dry tons of the material annually and it all has to go somewhere. If farmers and residents didn’t use it the city would have to pay landfill disposal fees to dump it.

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