Determine the size of the problem
An average horse (weighing 1000 lbs) will produce 30 - 45 lbs of feces and 2-3 gallons of urine per day. To this must be added the volume of soiled bedding removed from the stall daily, bringing the total for one horse to 876 cu ft per year. This equates to 2.4 cu ft per horse per day.
Compost and other bulk materials are frequently sold by the cubic yard. What is a cu yard? It is a cube that is 3ft wide by 3ft long by 3ft high. One cubic yard = 27 cubic feet.
Choosing a composting system
Choose a composting system to meet your needs, depending on how many horses you have, the space and equipment available, and how intensively you plan to manage your manure pile.
Free-standing static compost piles
Requirements: space for piles; front-end loader
A simple free-standing pile can make an effective composting system. The pile grows as manure and bedding are continually added to the top or sides. When the pile gets too big, additional piles can be created. Frequent turning of the pile with the front-loader will hasten the composting process and help reduce parasites and weed seeds. Unfortunately this less labor intensive method means that parasites and weed seeds may not be adequately destroyed, and the decomposition process may not be complete. The pile may become a liability in terms of foul odor, attracting flies, as well as contaminating ground water.
Aerated static compost piles
Requirements: construction of bins; electrical blower, timer and perforated piping ($1,000 - $50,000 depending on size)
As the name implies, static piles of barn waste are contained in large bins constructed for the purpose, and air is introduced at the base of the pile by a blower on an intermittent switch. There is no periodic mixing or turning of the material in the bins, so there may be anaerobic pockets left where decomposition is not complete, allowing parasites and weed seeds to survive, and foul odors to persist.
We recommend composting in windrows for several reasons:
• Your first-stage collection area is emptied and cleaned every month.
• Barn waste is moved monthly to the windrow where the material is mixed and turned regularly.
• Hand-held probes measure the moisture content and temperature in the windrow indicating when it should be watered or turned until the process is complete.
Example: Calculate the space needed for manure collection pile (based on 6 horses)
(a) calculate waste volume 2.4 ft³/horse/day x (6 horses) = 14.4ft³/day
(b) calculate immediate storage required: 14.4 ft³/day x 30 days = 432 ft³
(c ) Bin size
Volume = length x height x width: 10ft x 5 ft x 10ft = 500ft³
For our example we are proposing a first-stage manure collection area outside the barn. This should be located a reasonable distance from barn — far enough removed that fly-nuisance is minimized - but close enough for easy muck-dumping by wheelbarrow or front-loader. The collection manure pile should be constructed on a concrete pad or on heavy clay soil to prevent contaminates from the manure leaching into groundwater. The pile should have containment walls so the pile can accommodate barn waste for one month before it is moved to the windrow site.
Every month, the material from the first-stage collection area is moved and formed into a long horizontal pile, called a windrow. Consideration to topography, water sources and accessibility by tractor for turning should be considered. Windrows are frequently located running along the outside of a pasture fence. The windrow is typically 5-6 ft high, 6 – 10 ft wide, and the next month’s material from the first-stage collection site is added to the end of the windrow, allowing it to grow in length to accommodate several months of barn waste.
In this manner, your first-stage collection site close to the barn is kept tidy and is cleaned out every month, when the material is moved to the windrow site. The material in the windrow is turned on a regular basis until the compost is ready for use (60 – 90 days), depending on the type of material being used as bedding, and moisture levels in the windrow.