Chicken manure was always highly prized but usually in short supply because preindustrial fowl weren’t caged in factories or permanently locked in hen houses and fed scientifically formulated mixes.  The chicken breed of that era was usually some type of bantam, half-wild, broody, protective of chicks, and capable of foraging.  A typical pre-1900 small-scale chicken management system was to allow the flock free access to hunt their own meals in the barnyard and orchard, luring them into the coop at dusk with a bit of grain where they were protected from predators while sleeping helplessly.  Some manure was collected from the hen house but most of it was dropped where it could not be gathered.  The daily egg hunt was worth it because, before the era of pesticides, having chickens range through the orchard greatly reduced problems with insects in fruit.

The high potency of chicken manure derives from the chickens’ low C/N diet:  worms, insects, tender shoots of new grass, and other proteinaceous young greens and seeds.  Twentieth-century chickens “living” in egg and meat factories must still be fed low C/N foods, primarily grains, and their manure is still potent.  But anyone who has savored real free-range eggs with deep orange yokes from chickens on a proper diet cannot be happy with what passes for “eggs” these days.

Fertilizing with pure chicken manure is not very different than using ground cereal grains or seed meals.  It is so concentrated that it might burn plant leaves like chemical fertilizer does and must be applied sparingly to soil.  It provokes a marked and vigorous growth response.  Two or three gallons of dry, pure fresh chicken manure are sufficient nutrition to GROW about 100 square feet of vegetables in raised beds to the maximum.

Exclusively incorporating pure chicken manure into a vegetable garden also results in rapid humus loss, just as though chemical fertilizers were used.  Any fertilizing substance with a C/N below that of stabilized humus, be it a chemical or a natural substance, accelerates the decline in soil organic matter.  That is because nitrate nitrogen, the key to constructing all protein, is usually the main factor limiting the population of soil microorganisms.  When the nitrate level of soil is significantly increased, microbe populations increase proportionately and proceeds to eat organic matter at an accelerated rate.

That is why small amounts of chemical fertilizer applied to soil that still contains a reasonable amount of humus has such a powerful effect.  Not only does the fertilizer itself stimulate the growth of plants, but fertilizer increases the microbial population.  More microbes accelerate the breakdown of humus and even more plant nutrients are released as organic matter decays.  And that is why holistic farmers and gardeners mistakenly criticize chemical fertilizers as being directly destructive of soil microbes.  Actually, all fertilizers, chemical or organic, indirectly harm soil life, first increasing their populations to unsustainable levels that drop off markedly once enough organic matter has been eaten.  Unless, of course, the organic matter is replaced.