In agriculture, windrow composting is the production of compost by piling organic matter or biodegradable waste, like animal manure and crop residues, in long rows (windrows). This method is suited to producing large volumes of compost. These piles are generally turned to improve porosity and oxygen content, mix in or remove moisture, and redistribute cooler and hotter portions of the pile. Windrow composting is the most commonly used of farm scale composting methods. Process control parameters include the initial ratios of carbon and nitrogen rich materials, the amount of bulking agents added to assure air porosity, the pile size, moisture content, and turning frequency.

Compost windrow turners were developed to produce compost on a large scale. They are a traditionally a large machine that straddles a windrow of approximately eight feet high by 13 feet across. Although smaller machines exist for smaller windrows, most operations need the larger machines to be efficient. Turners drive through the windrow at a slow rate of forward movement. They have a steel drum with paddles that are rapidly turning. As the turner moves through the windrow, fresh air containing oxygen is injected into the compost by the drum/paddle assembly and waste gases produced by harmful bacteria are eliminated. The oxygen feeds the beneficial composting bacteria and thus speeds the eventual composting process. This process is then extended by windrow dynamics.

To properly utilize a compost windrow turner, it is ideal to compost on a concrete pad; haul in the feed stocks, and place them into windrows. Heavy-duty compost windrow turners can be built that allow the user to obtain optimum results. By using 4-wheel-drive or tracks the windrow turner is capable of turning compost in windrows located in remote locations. With a self-trailering option this allows the compost windrow turner to convert itself into a trailer to be pulled by a semi-truck tractor. These two options combined allow the compost windrow turner to be easily hauled anywhere and to turn the compost in muddy and wet locations.

Bacteria Farming:
There is no magic, no shortcuts, only MANAGEMENT. Composting is simply a matter of making the indigenous bacteria very very happy. If these bacteria are kept at their optimum environmental conditions: plenty to eat, good room temperature, and lots and lots of fresh air, they will perform their natural work - making finished compost, in record time without odors.

Windrows Dynamics:
Windrow Dynamics is basically the natural or unassisted airflow and subsequent bacterial activity of an undisturbed windrow caused by the rising of heated air. The following cross sectional drawing illustrates the concept of Windrow Dynamics.
 

In the above illustration, Zone # 1 represents what is referred to as the Dead Zone, or the anaerobic spot that normally begins immediately in a newly formed windrow. Zone # 2, which is the most active zone, is the hottest and has the most biological activity. This Zone is the ideal zone. It can be the "Sweet Spot" of composting. It is possible, however, to have temperatures rise too high in this zone and begin to destroy beneficial bacteria. Zone # 3 is the least compact zone in the entire row. It is cooler than Zone #2 but warmer than Zone #1. Bacterial activity in this Zone slows down rapidly as the moisture evaporates and cool air penetrates it.

Forming of the Zones:
FORMING OF THE ZONES In most new windrows, other than straight yard debris, Zone # 1 begins to form immediately and increases in size rapidly. The little Oxygen that exists is consumed rapidly, and the relatively high moisture content of the material begins to settle here. Zone # 2 is basically indefinable yet but begins to form as a result of an active Zone # 3, which remains small but active. If the row is not mixed and aerated soon it will all become Zone # 1. This is the most critical point because the odors generated can be the cause of site closing ODORS. These Zones must be refreshed promptly. All the material must change places and preferably change zones. This is accomplished by completely mixing and aerating the windrow, which is exactly what the Frontier windrow turner/aerator is designed to do.

Benefits of 100% Mixing:
1. Vast reduction of Odors (a major cause of site closures), which are caused by:
A. Cold spots due to little or no aerobic bacterial activity.
B. Anaerobic pockets due to excess moisture collection.
C. Anaerobic pockets due to lack of oxygen.
D. Old Clumps when they are finally broken open.

1. It substantially increases the diversity of organisms working in material.
2. More complete biological breakdown of the material.
3. The finished product is consistent.
4. Insuring the broadest variety of microorganisms in finished product to encourage plant life.

Breathing:
Aeration is not "agitation" nor the mere exposing of the material to the ambient air inside the tunnel as roto-tiller or flat paddle type turners do. The ambient air in the tunnel can be full of Carbon Dioxide released from inside the pile and short on much needed Oxygen. Like breathing into a paper bag. The essence of successful turning/aeration is to force (and retain) fresh breathable air into all the material, and to completely "disrupt," "reshape" and "restack" the row. This action thoroughly exchanges the material in all three Zones creating an entire row with the characteristics of Zone # 2. The Windrow Dynamics will, over time, reform the three Zones. Therefore, proper timing of the turns will lead to a reduced in size in both Zone # 1 and Zone # 3.

Consistency:
When a baker is baking a cake from scratch he does not simply add all the material in a bowl and stir it with a fork for a few seconds then expect the cake to turn out OK. His primary purpose for stirring is to THOROUGHLY mix all the ingredients, eliminate chunks and insure consistency and complete activity of the ingredients. The finished product, the cake, will be as good as the ingredients and how well they are blended. No matter how you cut it, being able to produce consistent, mature compost with little or no odors does not happen by accident.