COMPOSTING FACTS
BACTERIA FARMING

RCE wish to thank Tubgrinders Australia Pty Ltd for allowing us to include this interesting page in our site.

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 odours.

WINDROW 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

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 odours generated can be the cause of a site closing or fined by Regulatory Bodies.

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 a windrow turner/aerator is designed to do.

PARTICLE SIZE

There are three basic operations of a good windrow turner. The first is the phenomena of continued particle size reduction without creating anaerobic pockets (odours). It does not grind or pulverize the material, however, as the structure integrity of the material weakens due to bacterial activity the collisions caused by the vortex action within the tunnel begins shattering the weakened particles into smaller jagged shape pieces.

This increased surface area dramatically accelerates microbial activity. Thus accelerating material breakdown resulting in a higher percentage of finished product passing through the final sizing screen. Golf Courses and Turf growers, for example, will pay more for ¼” minus material.

AIR FLOW

This brings us to the next basic operation of an effective windrow turner. They generate fresh air while turning large quantities of material. A turner can move over 15 times more air than material. Forcing air into the material is important; keeping it there is vital.

To retain as much of this air as possible, it is critical NOT to squeeze the material like a sausage maker as it comes out the rear of the tunnel. Picking up the material and dropping it back onto itself only EXPELS the Oxygen from within. It is only common sense to retain as much oxygen as possible to ensure maximum 'Windrow Dynamics'.

100% MIXING IS CRITICAL

The third action of an efficient windrow turner is mixing. The values of this action are:

	It assures that ALL the materials is being exposed to every position in the row.
	It distributes the various Bacterial colonies to every part of the row.
	It re-establishes families of Microbes destroyed by high temperatures in Zone #2 or lack of Oxygen in Zone #1.
	It distributes the Nutrients to every part of the row.
	It allows the windrow dynamics to begin with the Zone #2 condition.
	It distributes the moisture evenly throughout the material.
	It equalizes the heat to every area of the row.
	It intersperses Varying types of material throughout the mix.
	It’s a matter of eliminating clumps, aerating the materials and most importantly, mixing it thoroughly.

BENEFITS OF 100% MIXING

BREATHING

Aeration is neither “agitation” nor the mere exposing of the material to the ambient air inside the tunnel as the common 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 Dynamic 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 odours does not happen by accident. It is the result of properly using the action of a Windrow Turner.

Purchasing a windrow turner should not be a matter of the lower price, it is a matter of which machine will produce the highest quality product in the shortest possible time with the LEAST odours. Getting more finished product in less time with the same effort can be the difference between breaking even and making a substantial profit.