I was glad to see the article in the July 19 Town-Crier entitled, “Wellington Eyes Progress Solving Manure Woes.”
I have been studying phosphorus pollution from equine waste, mainly manure, since 2004. The goal for phosphorus (P) making it into the Everglades is 10 parts per billion (ppb), which is 10 micrograms per liter (~1.06 quarts) of water. Analyses of numerous manure samples from farms, roads and in both Wellington and Loxahatchee Groves revealed total phosphorus contents of 13 milligrams per gram, dry weight (= 0.013 g. Note, 454 grams = 1 pound) of which half is what is called soluble reactive phosphorus (SRP), the most available form for algae and other plants.
The article mentioned above shows 12,000 horses in the season in Wellington and 31 pounds of manure per day per horse. That equals 372,000 pounds (186 tons manure per day). Manure averaged about 57 percent water, so 43 percent (0.43x), that gives 372,000 x 0.43 = 159,960 pounds of dry weight manure per day. With 454 grams per pound, the manure total per day is 454 g/lb. x 159,960 pounds, or 72,621,840 grams dry weight manure per day. Multiplying 13 mg / g dry weight manure times that value shows that 944,083,920 mg-P, equaling 944,084 grams or 2,080 pounds of phosphorus are available for pollution each day.
Considering only six months of the year at a full contingent of horses just in Wellington, one can now see that more than (180 days x 2,080 pounds) 373,400 pounds (187 tons) of phosphorus will enter the soils and eventually surficial waters by percolation and runoff. During a rainstorm in 2014, I measured more than 8 parts per million (8 milligram / liter: Yes = 8,000 ppb) in the drainage from a nursery in Loxahatchee Groves that had manure and manure/urine contaminated bedding spread over its property in excessive amounts — a problem deriving from tipping fee abuse. (Example: “My nursery needs only two truckloads but you pay me by the truckload, so bring me 60 truckloads!”)
Recycling is the answer, but recycling should also consider hauling distance, since trucking these materials over long distances adds to the carbon dioxide and diesel particulate pollution of the atmosphere, both of which factor into global warming.
In May 2012 and again in November 2014, I sent letters of support for recycling to the mayor and council of Wellington. I have also done similar letters to the Palm Beach County Commission years ago. Neither agency would work with recyclers, such as EquineEcoGreen to find a suitable close location for a recycling center. (I have no fiscal link with this company, which Ocala welcomed with open arms!) NIMBY (Not In My Backyard) reasons are the likely culprits. Shame on all of those who will not work to get recycling done in close proximity to the sites of generation. Recycling of the bedding helps save trees, and any recycling should be done in a 100 percent environmentally friendly manner. For instance, any and all water used in the process should be recycled internally and never put into surficial waters or aquifers. Recycling of the organic portion of the manure allows a product with known N:P:K contents to then be used as fertilizer/soil amendment within Best Management Practices (BMPs) as opposed to just spreading tons of manure with highly fluctuating N:P:K contents due to unknown manure / bedding ratios in each truckload.
The above considers only phosphorus, but nitrogen (N) is also in manure and bedding, which is saturated with urine containing urea, a highly available N source for algae). Both P and N pollution lead to harmful algal blooms in canals and lakes, cattail takeover of the Everglades and other problems.
Recycling is the answer — just do it! All it will take is for governmental officials to modify industrial zoning in sensible ways.
I thank you for your time and consideration. Sorry for all the math, but it needs to be shown.
Dr. J. William “Bill” Louda, Loxahatchee Groves
Editor’s note: Dr. Louda is a research professor at Florida Atlantic University.