The paradox of green organic matter: Why fresh manure is poison, but green manure is gold

“ We have already seen that plant food which is not available might as well be, for our immediate purposes, at the North Pole. The plant food in "green" or fresh manure is not available, and does not become so until it is released by the decay of the organic matters therein. Now the time possible for growing a crop of garden vegetables is limited; in many instances it is only sixty to ninety days. The plants want their food ready at once; there is no time to be lost waiting for manure to rot in the soil. ”

“ This is an item in Rose-culture that one cannot afford to ignore, if he desires fine Roses.
A rich soil must be provided for the plants in order to secure good results. This, also, is a matter of the greatest importance. The ideal fertilizer is old, well-rotted cow-manure—so old that it is black, and so rotten that it will crumble at the touch of the hoe. On no account should fresh manure be used. If old manure cannot be obtained, substitute finely-ground bonemeal, in the proportion of a pound to as much soil as [Pg 132] you think would fill a bushel-basket, on a rough estimate. ”

“ If you gain more than you need by three sowings, should all succeed, you have friends and neighbors enough, if you are a reasonably decent man, who will be glad to receive the surplus.
Manure.—Corn and potatoes will bear green and unfermented manure. But all ordinary garden vegetables require thoroughly rotted manure. If the soil is sandy, leached ashes may be applied with great profit at the rate of seventy or eighty bushels the acre. The soil is made more retentive of moisture, and valuable ingredients are secured to it. ”

“ Dig deep to loosen the soil; (2) Spread over it well-rotted manure; (3) Dig and turn the soil over again; (4) Rake the top soil fine and level.
It is a good plan to spread leaves and manure over the ground in the Fall and dig them in in the Spring to make the soil rich and crumbly, or friable.
Did you ever think how many different parts of plants are used for food?
We eat the roots of some vegetables; such as beets, carrots, radishes, turnips.
Of others we use the leaves; such as lettuce, celery, cabbage, spinach, parsley. ”

“ The complete extirpation of weed growth thus brought about, at first considered an unmixed benefit, has ultimately had to be made up for by the practice of green-manuring; since in the arid region the use of stable manure encounters many difficulties.
Estimation of Humus in Soils. It has been usual to determine the amount of humus in soils by means of (dry or wet) combustion, calculating the humus from the carbonic dioxid so formed, while measuring the nitrogen gas directly. But in this process the entire organic matter of the soil, humified and unhumified, is indiscriminately included ”

“ Of vegetable substances, it may be generally observed, that almost every sort of vegetable, not of woody texture, buried in the soil while green, is more or less efficacious as a manure; and that many sorts of these, when turned under where they grew, and while in a green state, will add much more fertility to the soil than their growth extracted from it ”

“ For green manure nothing is better than cowpeas as a summer crop and crimson clover as a winter crop. The crimson clover should be turned under about the time it comes into full bloom in the spring, the land planted to cowpeas, and the resulting crop plowed under or mowed for hay during the month of August in ample time to prepare the land for frame work during the autumn. When heavy crops of green manure are turned under it is essential that lime be used to improve the mechanical condition and to sweeten the soil; a dressing of 1,000 pounds to the acre should be sufficient. ”

“ Fertilized with sacked steer manure or mulched with average-to-poor compost, most ornamentals will grow adequately.
But vegetables are delicate, pampered critters that must grow as rapidly as they can grow if they are to be succulent, tasty, and yield heavily. Most of them demand very high levels of available nutrients as well as soft, friable soil containing reasonable levels of organic matter. So it is extremely important that a vegetable gardener understand the inevitable disruption occurring when organic matter that has a C/N is much above 12:1 is tilled into soil. ”

“ Most important, humus is the last stage in the decomposition of organic matter. Once organic matter has become humus it resists further decomposition. Humus rots slowly. When humus does get broken down by soil microbes it stops being organic matter and changes back to simple inorganic substances. This ultimate destruction of organic matter is often called nitrification because one of the main substances released is nitrate—that vital fertilizer that makes plants grow green and fast. ”

“ Organic matter that has been in soil for a while has been altered into a much studied substance, humus. We know for example that humus always has a carbon to nitrogen ratio of from 10:1 to about 12:1, just like compost from Garden "B." Garden writers call great compost like this, "stable humus," because it is slow to decompose. Its presence in soil steadily feeds a healthy ecology of microorganisms important to plant health, and whose activity accelerates release of plant nutrients from undecomposed rock particles. ”

“ Green crops, pond weeds, the paring of hedges or ditches, or any kind of fresh vegetable matter, requires no preparation to fit them for manure. The decomposition slowly proceeds beneath the soil; the soluble matters are gradually dissolved, and the slight fermentation that goes on, checked by the want of a free communication of air, tends to render the woody fibre soluble without occasioning the rapid dissipation of elastic matter. ”

“ Just as in a compost heap, within days bacteria and fungi can multiply to match any food supply. But to construct their bodies these microorganisms need the same nutrients that plants need to grow—nitrogen, potassium, phosphorus, calcium, magnesium, etc. There are never enough of these nutrients in high C/N organic matter to match the needs of soil bacteria, especially never enough nitrogen, so soil microorganisms uptake these nutrients from the soil's reserves while they "bloom" and rapidly consume all the new carbon presented to them. ”

“ As with corn, the ground is tilled bare, so for much of the best part of the growing season little or no organic matter is produced. Of all the crops that a person can grow, vegetables are the hardest on soil organic matter. There is no way that vegetables can maintain soil humus, even if all their residues are religiously composted and returned. Soil organic matter would decline markedly even in an experiment in which we raised some small animals exclusively on the vegetables and returned all of their manure and urine too. ”

“ Vegetable gardeners have traditionally been acutely interested in composting, soil building, and maintaining soil organic matter. We are willing to consider anything that might help us grow a better garden and we enjoy agricultural science at a lay person's level. ”

“ All microorganisms, including nitrogen-fixing bacteria, build their bodies from the very same elements that plants use for growth. Where these mineral elements are abundant in soil, the entire soil body is more alive and carries much more biomass at all levels from bacteria through insects, plants, and even mammals. ”

“ Recall my assertion that what is most important about organic matter is not how much is present, but how much is lost each year through decomposition. For only by decomposing does organic matter release the nutrients it contains so plants can uptake them; only by being consumed does humus support the microecology that so markedly contributes phytamins to plant nutrition, aggressively breaks down rock particles and releases the plant nutrients they contain; only by being eaten does soil organic matter support bacteria and earthworms that improve productivity and create better tilth. ”

“ As manure is full of the seeds of weeds and grasses, it is better, when applying it in the spring, to remove a portion of the top-soil and work the manure into the subsoil by spading, and then to return the top-soil. This will prevent their germination and save a great deal of weeding during the summer. ”

“ If the earth is heavy loam and inclined to cake or mould, add a little sifted sand and a thin sprinkling of either nitrate of soda or one of the "complete" commercial manures. Barn-yard manure, unless very well rotted and thoroughly worked under, is apt to develop fungi destructive to seedlings. This will be sufficient preparation if the soil is in average condition; but if the earth is old and worn out, it must be either sub-soiled or dug and enriched with barnyard (not stable) manure to the depth of a foot, or more if yellow loam is not met below that depth. ”

“ Yet rest assured of one thing, Socrates: if after you have put seed into the ground, you will await the instant when, while earth is being richly fed from heaven, the fresh green from the hidden seed first springs, and take and turn it back again, (12) this sprouting germ will serve as food for earth: as from manure an inborn strength will presently be added to the soil. ”

“ All green succulent plants contain saccharine or mucilaginous matter, with woody fibre, and readily ferment. They cannot, therefore, if [169] intended for manure, be used too soon after their death.
When green crops are to be employed for enriching a soil, they should be ploughed in, if it be possible, when in flower, or at the time the flower is beginning to appear, for it is at this period that they contain the largest quantity of easily soluble matter, and that their leaves are most active in forming nutritive matter. ”

“ On the richer lands, the aim of the farmer will be to convert the plant food lying dormant in the soil into profitable crops. The main point is good tillage. In many cases weeds now run away with half our crops and all our profits. The weeds which spring up after the grain crops are harvested, are not an unmixed evil. They retain the nitrogen and other plant food, and XX when turned under make manure for the succeeding crops. But weeds among the growing crop are evil, and only an evil. Thorough plowing is the remedy, accompanied by drainage where needed. ”

“ Earnest digging, liberal manuring, and scrupulous cleansing are the tasks that stand forward as of pre-eminent importance. Many weeds, groundsel especially, will now be coming into flower, and if allowed to seed will make enormous work later on. It is well, however, to remember—what few people do remember, because the fact has not been pressed upon their attention—that weeds of all kinds, so long as they are not in flower, are really useful as manure when dug into the soil. ”

“ Gardeners often use the terms organic matter, compost, and humus as interchangeable identities. But there are important differences in meaning that need to be explained.
This stuff, this organic matter we food gardeners are vitally concerned about, is formed by growing plants that manufacture the substances of life. Most organic molecules are very large, complex assemblies while inorganic materials are much simpler. Animals can break down, reassemble and destroy organic matter but they cannot create it. ”

“ Organic matter decomposing in soil opens and loosens soil and makes the earth far more welcoming to plant growth. Its benefits are both direct and indirect. Decomposing organic matter mechanically acts like springy sponges that reduce compaction. ”

“ If the organic matter has a low C/N, like manure, a tender green manure crop not yet forming seed, alfalfa hay or grass clippings, quite a large volume of material can be decomposed by warm soil in a matter of weeks.
However, rotting large quantities of very resistant material like sawdust can take many months, even in hot, moist soil. Most gardeners cannot afford to give their valuable land over to being a compost factory for months. One way to speed the sheet composting of something with a high C/N is to amend it with a strong nitrogen source like chicken manure or seed meal. ”

“ 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. ”

“ But home gardeners and market gardeners near cities are able to get their hands on virtually unlimited quantities of organic matter. Encouraged by a mistaken belief that the more organic matter the healthier, they enrich their soil far beyond any natural capacity. Often this is called "building up the soil." But increasing organic matter in gardens well above a climax ecology level does not further increase the nutritional value of vegetables and in many circumstances will decrease their value markedly. ”

“ Making compost is also a "personal good." For a few hours a year, composting gets you outside with a manure fork in your hand, working up a sweat. You intentionally participate in a natural cycle: the endless rotation of carbon from air to organic matter in the form of plants, to animals, and finally all of it back into soil. You can observe the miraculous increase in plant and soil health that happens when you intensify and enrich that cycle of carbon on land under your control. ”