A little horse manure goes a long way in polluting water
The equestrian season is once again upon us. This a fantastic industry that provides many jobs, financial gains for Palm Beach County and tremendous entertainment for observers, such as myself. However, it also comes with a huge environmental burden — hundreds of thousands of tons of nitrogen and phosphorus-laden wastes.
I have been studying phosphorus pollution from horse manure and bedding wastes for more than a decade, and can offer some simple math. The waters of South Florida need to have low levels of phosphorus (P) for the Everglades, Lake Okeechobee and our coastal waters to function properly. The target for the Everglades is 10 parts per billion (10 ppb = 10 micrograms per liter).
One point source that I sampled was a nursery that has a lot of horse waste and, following a rain, the waters coming off that property had 7,958 ppb, basically 8 milligrams of phosphorus per liter. Startled by this result, I ran the analysis three times. I got the same results.
Using only water and very dilute bicarbonate solutions, typical of Florida conditions, horse manure collected from the Wellington and Loxahatchee areas averaged 4.3 mg of phosphorus per gram manure wet weight. Using the 8.5 tons of manure per horse per year estimated by Palm Beach County Planning, this equates to 454g/pound x 2,000 pounds (ton) x 8.5 tons = 7,718,000 grams manure per horse per year. With the average phosphorus content of 4.3 mg of phosphorus/ gram wet manure that converts to 33,187,400 mg (33,187 g) or 73 pounds of phosphorus per horse per year.
One can then extrapolate this to 10,000 horses and get a value of 730,000 pounds of phosphorus available to leach into the surface waters of South Florida.
Rather than dumping and spreading this waste, recycling is a much better option. In that way, bedding (wood chips) gets cleaned and reused, and the organic matter plus nutrients get packaged into pellets for use as fertilizer with known nitrogen and phosphorus contents that can then be applied in line with best management practices.
Very viable recycling options are presently available and are known by the County Commission. It is way past time to move forward for the health of South Florida’s aquatic environments.