Weymouth, Mass. — It is not generally realized, but the Soviet invasion of Afghanistan may well have delayed by decades a crisis in US agriculture that could extend all the way down to the home gardener -- organic gardeners excepted. It has enabled the federal government to suspend the export to the Soviet of dwindling supplies fo phosphate rock.
Under the present system of grow-it and throw-it-away agriculture, vast quantities of phosphate, mostly in the form of superphosphate, are consumed every year. At the same time domestic supplies of readily available phosphate from Florida mines are tailing off and could be exhausted by 1995. After that, the only remaining major sources of the important mineral would be in North Africa, a National Academy of Sciences of World Food and Nutrition Study (1977) points out. The very people who now control the oil future would then have impressive leverage in another critical area, too.
With seeming lack of foresight, the United States contracted some years ago to supply more than half of its remaining phosphate reserves to the Soviet Union. But with the invasion of Afganistan, it has been able to suspend that contract and, officials hope, will find a way of breaking it altogether. In such a situation, the US reserves will be available for home consumption for perhaps another decade or two. As it is, phosphate rock prices have skyrocketed in recent years. From $8 a ton in 1972 it has leaped to $200 a ton, and predictions are that it will be around $400 in little more than a year or two.
Meanwhile, the National Fertilizer Institute has warned that sometime in the '90s natural gas may no longer be available as a feedstock for the production of nitrogen fertilizers. The demands of industry and home heating will simply make gas too expensive as a raw material for the much-used fertilizer. Coal is seen as an alternative, but not even a pilot plant to test the coal-to-fertilizer theory has yet been built.
These stories underscore again the new reality: the need to conserve and recycle in all spheres of life. Many productive organic gardens were given a flying start by the initial inclusion of mineral rock in the soil. That done, the needed supply of the basic minerals has been maintained by a disciplined program for composting or mulching, or both, which has recycled the nutrients back to the soil. Even without the use of mineral rock, heavy manuring or composting will readily rejuvenate depleted soil.
To grow vigorously, plants need three major elements: nitrogen (N) for lush green growth, phosphorus (P) for strong root development, and potassium (K) for general vigor and well-being. Along with these, plants require a host of other elements in moderate or trace form. These minor elements are generally available in adequate quantities in most soils.
Anyone who plows back organic wastes or finished compost, or mulches with these materials, is unlikely ever to have soil that is short in plant nutrients. But it might be worth noting the NPK values, expressed as a percentage of their weight, of some of the ones more readily available here:
Alfalfa hay, 2-1-2; apple leaves, 1-0-0; brewers grains; 1-1-0; cocoa shell dust, 1-1- 3; cofee grounds, 2-0-0; chicken manure (fresh), 1-1-1; dog manure, 2 -10-0; egg- shells, 1-0-0; feathers, 15-0-0; freshwater mud, 1-0-0; hair, 14-0-0 ; incinerator ash 0- 5-2; leather dust, 10-0-0; lobster shells, 5-4- 0; peanust shells, 1-0-1; pigeon manure, 4-2- 1; rabbit manure, 2-1-1; salt-marsh hay, 1- 0 -1; seaweed, 2-1-5; tea grounds, 4-1-0; wood ash, 0-2-4; wool waste; 5-3-2.
Leaves and many other commonly available organic materials have not been mentioned here because their NPK percentages are around 1 or less. But it should be remembered that as these materials decay and lose weight and volume in the compost pile or within the soil, their nutients remain.As a result, their NPK values go up.
Many gardeners pay little heed to NPK values of their composting materials. They have learned simply to feed the soil organisms with whatever is available. These organisms, in turn, convert the material into the nutrients the plant can take up in solution. The point, then, is to use whatever organic materials one has or can get hold of. The more we recycle, the less pressure we will put on the dwindling reserves of phosphate rock and other minerals important to agriculture.