Archive for April, 2009

The Soil – Its Life and Fertility

– Five to ten tons of animal life can live in an acre of soil. (National Wildlife Federation)

– Worm casts contain five times as much nitrogen, seven times as much available phosphate, eleven times as much available potash, three times as much available magnesium, and one and a third times as much available calcium as the soil of the top six inches. (H.G.M. Jacobson and H.A. Lunt, “Soil Science”)

– All these extreme types (of soil) have one thing in common. They are all improved, cumulatively, by decaying organic matter. They are improved in two ways. By an improvement in structure and an improvement in water-holding capacity. This is brought about by the presence of large numbers of bacteria and fungi and their remains, which are of a mucilaginous or gummy nature. (P.H. Hainsworth, “Secrets of an Expert Organic Gardener”)

– Soil, particularly a fertile soil, is much more alive than a casual glance would show. We can see the larger insects and worms but the greater bulk of living things is invisible – consisting of bacteria, fungal mycelium, and a variety of less well known organisms. …The population varies according to moisture and warmth of the soil. For bacteria…about 3,000,000,000 per gram of soil, weighing a ton to the acre, in the top 6 inches. (P.H. Hainsworth, “Secrets of an Expert Organic Gardener”)

– Organisms in the soil in addition to bacteria and earthworms include fungi, actinomycetes, algae, protozoa, centipedes, millipedes, springtails, spiders, mites, eelworms, insects and their larvae. (P.H. Hainsworth, “Secrets of an Expert Organic Gardener”)

– It may come as something of a surprise to the farmer to know that he has 30 times as much stock underground as on the field. There have been estimates of 40 tons per acre…. (P.H. Hainsworth, “Secrets of an Expert Organic Gardener”)

– The amount of earth moved annually (by earthworms) is prodigious. Recent estimates of the amount of soil cast annually per acre in pastures by worms are between 1 and 25 tons on the surface and 4 to 36 tons underground. This results in a pore space in the soil of between 40 and 67 percent, according to the proportion of surface-casting species. (A.C. Evans, “Annual of Applied Biology”)

– The amount of food consumed by these various organisms (in the soil) is considerable. …Given an annual dressing of manure at 14 tons per acre, (they) used the same number of calories daily as 12 men. While this may seem a great waste of food, it contains almost entirely of cellulose, lignin, and humus, which is inedible, as far as people are concerned. (P.H. Hainsworth, “Secrets of an Organic Gardener”)

– Conclusive evidence of the release of minerals by microbiological activity on the organic section (of the farm is that) potash and phosphate are at a similar level during winter, but rise rapidly as the crop grows in May and June to a level representing eight times as much by mid-summer. This is followed by an equally swift decline with the ripening of the crop. …The minerals are rendered available as the crop needs them and cease to be so as the crop ripens – a protection against possible loss. P.H. Hainsworth, “Secrets of an Organic Gardener”)

– Green manuring is popularly believed to be a good method of building soil fertility. It can be, but, as practiced today, it is anything but. The ploughing in of a soft, young, green crop adds a large amount of nitrogen to the soil relative to the amount of carbohydrate or plant fiber. Some farmers even add extra nitrogen to rot it down. …This results in a net decrease in the amount of organic matter in the soil. To be effective, the green crop must be allowed to mature. (P.H. Hainsworth, “Secrets of an Organic Gardener”)

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