Fertilizing Vegetables with Compost
Will a five ton per acre addition of compost provide enough nutrition to grow great vegetables? Unfortunately, the answer usually is no. In most gardens, in most climates, with most of what passes for "compost," it probably won't. That much compost might well grow decent wheat.
The factors involved in making this statement are numerous and too complex to fully analyze in a little book like this one. They include the intrinsic mineralization of the soil itself, the temperature of the soil during the growing season, and the high nutritional needs of the vegetables themselves. In my experience, a few alluvial soils that get regular, small additions of organic matter can grow good vegetable crops without additional help. However, these sites are regularly flooded and replenished with highly mineralized rock particles. Additionally, they must become very warm during the growing season. But not all rock particles contain high levels of plant nutrients and not all soils get hot enough to rapidly break down soil particles.
Soil temperature has a great deal to do with how effectively compost can act as fertilizer. Sandy soils warm up much faster in spring and sand allows for a much freer movement of air, so humus decomposes much more rapidly in sand. Perhaps a sunny, sandy garden on a south-facing slope might grow pretty well with small amounts of strong compost. As a practical matter, if most people spread even the most potent compost over their gardens at only twenty-five pounds per 100 square feet, they would almost certainly be disappointed.
Well then, if five tons of quality compost to the acre isn't adequate for most vegetables, what about using ten or twenty tons of the best. Will that grow a good garden? Again, the answer must allow for a lot of factors but is generally more positive. If the compost has a low C/N and that compost, or the soil itself, isn't grossly deficient in some essential nutrient, and if the soil has a coarse, airy texture that promotes decomposition, then somewhat heavier applications will grow a good-looking garden that yields a lot of food.
However, one question that is rarely asked and even more rarely answered satisfactorily in the holistic farming and gardening lore is: Precisely how much organic matter or humus is needed to maximize plant health and the nutritional qualities of the food we're growing? An almost equally important corollary of this is: Can there be too much organic matter?
This second question is not of practical consequence for biological grain/livestock farmers because it is almost financially impossible to raise organic matter levels on farm soils to extraordinary amounts. Large-scale holistic farmers must grow their own humus on their own farm. Their focus cannot be on buying and bringing in large quantities of organic matter; it must be on conserving and maximizing the value of the organic matter they produce themselves.
Where you do hear of an organic farmer (not vegetable grower but cereal/livestock farmer) building extraordinary fertility by spreading large quantities of compost, remember that this farmer must be located near an inexpensive source of quality material. If all the farmers wanted to do the same there would not be enough to go around at an economic price unless, perhaps, the entire country became a "closed system" like China. We would have to compost every bit of human excrement and organic matter and there still wouldn't be enough to meet the demand. Even if we became as efficient as China, keep in mind the degraded state of China's upland soils and the rapid desertification going on in their semi-arid west. China is robbing Peter to pay Paul and may not have a truly sustainable agriculture either.
I've frequently encountered a view among devotees of the organic gardening movement that if a little organic matter is a good thing, then more must be better and even more better still. In Organic Gardening magazine and Rodale garden books we read eulogies to soils that are so high in humus and so laced with earthworms that one can easily shove their arm into the soft earth elbow deep but must yank it out fast before all the hairs have been chewed off by worms, where one must jump away after planting corn seeds lest the stalk poke you in the eye, where the pumpkins average over 100 pounds each, where a single trellised tomato vine covers the entire south side of a house and yields bushels. All due to compost.
I call believers of the organic faith capital "O" organic gardeners. These folks almost inevitably have a pickup truck used to gather in their neighborhood's leaves and grass clippings on trash day and to haul home loads from local stables and chicken ranches. Their large yards are ringed with compost bins and their annual spreadings of compost are measured in multiples of inches. I was one once, myself.
There are two vital and slightly disrespectful questions that should be asked about this extreme of gardening practice. Is this much humus the only way to grow big, high-yielding organic vegetable gardens and two, are vegetables raised on soils super-high in humus maximally nutritious. If the answer to the first question is no, then a person might avoid a lot of work by raising the nutrient level of their soil in some other manner acceptable to the organic gardener. If the answer to the second question is less nutritious, then serious gardeners and homesteaders who are making home-grown produce into a significant portion of their annual caloric intake had better reconsider their health assumptions. A lot of organic gardeners cherish ideas similar to the character Woody Allen played in his movie, Sleeper.
Do you recall that movie? It is about a contemporary American who, coming unexpectedly close to death, is frozen and then reanimated and healed 200 years in the future. However, our hero did not expect to die or be frozen when he became ill and upon awakening believes the explanation given to him is a put on and that his friends are conspiring to make him into a fool. The irritated doctor in charge tells Woody to snap out of it and be prepared to start a new life. This is no joke, says the doctor, all of Woody's friends are long since dead. Woody's response is a classic line that earns me a few chuckles from the audience every time I lecture: 'all my friends can't be dead! I owned a health food store and we all ate brown rice.'Back to Composting
|Ultimate Survival Knife & Kit
List Price: 61.99
Our Price: 39.95
This 15 inch survival knife with drop point blade features a thick quality stainless steel blade with serrated top edge. Textured and ribbed solid metal handle and guard. Nylon sheath. Survival kit includes a hollow grip with a compass top to store items within the knife itself, as well as additional pouches on the sheath to hold the rest. Complete survival kit.Click Here to Buy the Survival Knife Now.