About Fertilizers

One of the basic principles of organic gardening is to feed the soil and let the soil feed the plants; then the plants can feed you. From a practical standpoint, there are two parts to the process of creating a continually healthy, productive garden:

  • First, we must find (or rebuild) a fertile, friable soil; and
  • Second, we must maintain that fertility despite the drain of year-in, year-out harvest.

Input must equal or exceed output; violate this equation and eventually your garden will decline.  It was a simplistic understanding of this nutrient flow process that led clean-handed theoreticians to skip the soil and concentrate on the plant. They assumed that to grow a plant you needed only apply inputs to some sort of medium that can hold the roots and support the plant, then inoculate it with a seed and stand back while the plant unfolds like one of those little smoke-and-ash snakes we played with as children.

Unfortunately, this reductionist vision assumes that the chemist knows and supplies everything the plant needs; it assumes simply that if the plant is green and grows, all is well.

The technical basis on which this belief is founded was developed by a German chemist, Justus von Liebig. He analyzed the chemical constituents of harvested plant tissue, and determined that it was largely composed of three elements: nitrogen, phosphorus, and potassium—the “N-P-K” listed today on every bag of purchased fertilizer. That there were hundreds, or maybe even thousands of other constituents, became of little concern; von Liebig found that plants responded to applications of simple compounds of these chemicals, particularly nitrogen.

Some seventy years later, another German chemist named Fritz Haber developed a method of synthesizing ammonia (which is one part nitrogen and four parts hydrogen). Haber was awarded the 1918 Nobel Prize in chemistry for this discovery, which made the manufacture of nitrogen economically feasible—a breakthrough which is now coming back to haunt us. Haber’s process was used by the Germans not to feed the world, however, but to try to dominate it—to manufacture the explosives that led Kaiser Wilhelm into World War I. Haber was deeply involved in warfare chemistry and directed the first use of chemical weapons in 1915. By the end of World War II a whole class of chemical killers had been developed by both sides.

Once hostilities ceased, all this technology was turned toward agricultural use, and the two major technological props that support current conventional gardening and farming methods are the direct results of this war research: Ammonia is now injected directly into the soil from tank trucks to provide nutrients that the dead land can’t provide, and chemicals that were created to kill our enemies are sprayed on the crops that we ourselves will eat. On the surface, gardening and farming have become a simple matter of inputs and outputs; but beneath the surface is a legacy of death, destruction, and pollution that continues to this day.

The multibillion-dollar yearly agricultural chemical business is a direct result of this profound simplification. The Achilles heel of man’s manipulation of nature is the substitution of an economically efficient and profitable simplicity for the (seemingly) inefficient yet stable complexity of natural systems and methods. Someday we will end up paying to correct the damage wreaked on the Earth by the widespread, ill-advised acceptance of this Faustian bargain. Today immense amounts of ammonia are synthesized from methane (natural gas) and used to produce synthetic fertilizers. But less than half of that applied to the soil is actually used by the plants; the rest evaporates or leaches into streams, ponds, and groundwater, where it causes nitrate pollution so diffuse and widespread it may be impossible to clean up.

Of course it’s possible to produce vegetable crops with chemicals alone, under artificial conditions; in fact it’s routinely done in hydroponic greenhouses. But while these vegetables may look normal, they lack some of the complex constituents of vegetables grown in a healthy, fertile soil. A 1992 article in the New York Times told of research which revealed that the plant pigment beta-carotene (responsible for the orange color of carrots), could help prevent cancer and heart disease. Beta-carotene, which is a precursor of vitamin A, is an ingredient in some over-the-counter vitamin pills; but the researcher who reported the findings recommended eating foods rich in beta-carotene rather than taking the vitamin pills. Why? Because beta-carotene is only one of about five hundred “carotenoids,” the larger group of related compounds to which it belongs. Other research had convinced him that combinations of different carotenoids are much more effective than beta-carotene alone. Carrots (and other foods like melons, kale, collards, winter squash, and pumpkins) contain a whole range of these carotenoids; the vitamin supplements, while they can be profitably manufactured, do not.

The richer and more complex the soil in which plants are grown, the better they are able to find what they need to create a more complex and therefore more nutritious root, shoot, or fruit. The outputs cannot be any better than the inputs once the natural fertility of virgin soil, on which the plants draw, is exhausted, and the hidden but essential quality of the crops can only drop when they must rely solely on the NPK supplements they’re fed from a bag. To believe otherwise is horticultural hubris.

So let’s take a look at N, P, and K, a what each does both in the plant and in the environment, and then at some of the other essential nutrients that are left out of the convenient modern “fast-food” fertilizers, along with the non-nutrient elements necessary for plant growth.

ShepherdAbout Fertilizers

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