When chemical fertilizers are spent, manure keeps on working

A few seasons back, a friend of mine ordered a pickup load of manure from a dairy farmer in his neighborhood. After he had spread all that his vegetable garden could reasonably accommodate, he still had a tidy pile left, so he planted squash seeds all around the edge.

The squash vines clambered all over the pile, effectively hiding it from any neighbors who might question the advisability of simply leaving it there. After rampant early vine growth, a score or so fruit set and grew almost explosively.

By harvesttime it took a strong man to lift some of those blue Hubbards.

The next year was a repeat of the first. Then last spring, with wild grasses having overtaken the now very-shrunken and decomposed manure pile (it resembled a rich, dark soil), he tried for yet another squash bonanza. For three years the rain had fallen on that unprotected pile, leaching out its nutrients, and it seemed reasonable to expect a vastly reduced harvest. But he struck it rich yet again.

My friend admits to having not kept detailed harvest records by weight, so he cannot say for sure that the third harvest still equaled the first. But the baby blue Hubbards (''I learned my lesson the first year,'' he says), and buttercup, perhaps the finest-flavored of all squashes, were again numerous.

The spaghetti squash, which he grew for the first time this year, were particularly productive.

Why should a pile of cow manure be that effective for so long? It hasn't anywhere near the nutrient punch of artificial fertilizers, coming in at something like 2-1-2 on the nitrogen/phosphoric acid/potash scale.

The fact is that while the nutrient analysis is low by chemical-fertilizer standards, it has other things going for it that are not available in conventional fertilizers. For one thing, the nutrients in manure (as with compost) are constantly being replaced as long as any manure remains to be decomposed.

Pour water through highly soluble chemical fertilizers and the nutrients are quickly washed away. All that remains is inert filler material. It has shot its bolt, so to speak. Do the same thing to the manure pile, and the available nutrients are also leached away. But what is left is far from inert filler material. It is loaded with bacterial life, which continues the work of decay, and so quickly produces more water-soluble nutrients. This process goes on until , finally, there is little or nothing left that can decay.

There are still other pluses to manure. In its passage through the digestive tract, the grass and other foodstuffs give up nutrients to the animal, but get a good deal back as well in the form of enzymes, hormones, and trace elements, along with a teeming bacterial population that enlivens the soil in ways still not readily understood.

Soil quality and structure are also improved with every application of manure. Test after test shows that plants growing in a manured field produce more abundantly than the chemical analysis says they should.

Now not everyone can get a load of fresh-from-the-farm manure the way my friend can. With the increasing appreciation of cow manure among gardeners and truck farmers, however, has come the increased availability of packaged manure. There are several brands, among them Bovung (an abbreviation, one assumes, of bovine dung). A proven product, it was off the market for some time because the wind blew too frequently from its processing fields toward a nearby housing subdivision. Now, a new processing plant in a new location has made production possible again.

In selecting a manure product, look for the word ''dehydrated'' (dried) on the bag, but avoid anything that says ''sterilized,'' for much of its beneficial microbial life, including enzymes, will have been destroyed.

In poor soils it is best to mix manure directly into the soil at about 40 pounds to 100 square feet of garden space. Otherwise, my preference is to sprinkle a little manure directly into the planting hole and to place the rest on the surface of the soil surrounding the plants.

I cover this in turn with a light mulch of shredded leaves, straw, or paper to shield the microbial life in the manure from the direct rays of the sun. Then , as the rains fall, they take up the soluble nutrients from the manure and percolate down to the roots as ready-made liquid manure.