There are other less obvious tumbler disadvantages that may negate any work avoided, time saved, or sweaty turning with a manure fork eliminated.  Being top-loaded means lifting compost materials and dropping them into a small opening that may be shoulder height or more.  These materials may include a sloppy bucket of kitchen garbage.  Then, a tumbler must be tumbled for a few minutes every two or three days.  Cranking the lever or grunting with the barrel may seem like fun at first but it can get old fast.  Decomposition in an untumbled tumbler slows down to a crawl.

Both the passive compost bin and the highly active compost tumbler work much better when loaded with small-sized particles.  The purchase of either one tends to impel the gardener to also buy something to cut and/or grind compost materials.

The U.C.  Method—­Grinder/Shredders

During the 1950s, mainstream interest in municipal composting developed in America for the first time.  Various industrial processes already existed in Europe; most of these were patented variations on large and expensive composting tumblers.  Researchers at the University of California set out to see if simpler methods could be developed to handle urban organic wastes without investing in so much heavy machinery.  Their best system, named the U. C. Fast Compost Method, rapidly made compost in about two weeks.

No claim was ever made that U. C. method produces the highest quality compost.  The idea was to process and decompose organic matter as inoffensively and rapidly as possible.  No attempt is made to maximize the product’s C/N as is done in slower methods developed by Howard at Indore.  Most municipal composting done in this country today follows the basic process worked out by the University of California.

Speed of decomposition comes about from very high internal heat and extreme aerobic conditions.  To achieve the highest possible temperature, all of the organic material to be composted is first passed through a grinder and then stacked in a long, high windrow.  Generally the height is about five to six feet, any higher causes too much compaction.  Because the material is stacked with sides as vertical as possible, the width takes care of itself.

Frequent turning with machinery keeps the heap working rapidly.  During the initial experiments the turning was done with a tractor and front end loader.  These days giant “U” shaped machines may roll down windrows at municipal composting plots, automatically turning, reshaping the windrow and if necessary, simultaneously spraying water.