How to measure nitrogen balance
In the 1960's, when the Central Intelligence Agency's (CIA) secret gadget-makers invented a listening device for the Asian jungles, they disguised it so the enemy wouldn't be tempted to pick it up and examine it: The device looked like tiger droppings.
The guise worked. Who would touch such a thing? The fist-sized transmitter detected troop movements along the trails in Vietnam.
While most people would find tiger droppings offensive, there are millions of gardeners who look at look at manure as money in the bank. Many zoos, for example, are marketing giraffe even hippopotamus droppings. Can you guess what the best zoo doo is? (You'll find the answer at the end of this article).
In the days when most families kept a milk cow and a flock of chickens, manure was a primary garden fertilizer. But with changes in food production practices and the advent of synthetic fertilizer in the 1930's, many gardeners stopped using manure. Today, organic gardeners have rediscovered the benefits of manure as a fertilizer, soil conditioner and compost ingredient .
Where to find manure
Remember the story of the little boy who was digging through the pile of manure? "There has to be a pony in here somewhere," he told his father.
The hopeful lad probably lived on a farm, the best place for home gardeners to get manure. Or any place where domestic animals are raised, for that matter. Just listen for moos and clucking! Farm manure is often sold as bagged manure and is available at garden centers and hardware stores.
Manures and composted plant materials add organic matter, which helps soil retain moisture and structure which prevents compaction, and helps prevent nutrients from leaching away. They also balance extremes in soil pH.
"The fairest thing in nature, a flower,
still has its roots in earth and manure."
D.H. Lawrence, English novelist, poet (1885-1930)
Good poop, bad poop
What is good for the goose, is not always good for the gander. There
are a few manures that should not be used, primarily those of meat eaters. According to Cornell University. "Homeowners should not use any manure from dogs, cats, or other meat-eating animals, since there is risk of parasites or disease organisms that can be transmitted to humans."
The most common sources of manure are horses, cattle, goats, sheep, rabbits and poultry. Below is a guide showing how manures measure up, nutrient-wise. While all animal manures are good sources of organic matter and nutrients, it's impossible to make a precise analysis, mostly because bedding materials vary so much. For example, manure with straw or sawdust will have a different nitrogen composition than pure manure. But it's useful to know whether the manure you're using is rich or poor in a particular nutrient such as nitrogen.
As you review the list, don't be misled by the N-P-K numbers that suggest manure is less powerful than chemicals. It is actually far better because it contains large amounts of organic matter, so it feeds and builds the soil while it nourishes the plants. This is one of the primary ways that organic fertilizers have a leg-up on chemical ones.
Still, many gardeners can't resist comparing the numerical amounts listed below with what they read on packages of synthetic fertilizers. Unfortunately, the values of manure and organic fertilizers in general, are often based on the relative amount of nitrogen (N), phosphoric acid (P) and potash (K) they contain. While these are important elements, "it is misleading to make a direct comparison between farm manures and chemical fertilizers on the basis of the relative amounts of N-P-K," says Jerry Minnich, author of Rodale's Guide to Composting .
Just like we need to eat to maintain our health, soil needs continual replenishment of its organic matter to decompose into humus. Humus helps create a rich, moisture-retaining soil and makes nutrients available to plants.( For more organic gardening tips, read the current issue of my UpBeet Gardener newsletter .)
How common manures measure upSource: www.plantea.com