Friday, July 15, 2011
It has been thought that the decay of past civilizations was due to a decline in soil fertility. If we think of the humus content of the soil as a bank account from which we only withdraw funds you will begin to understand the nature of the problem of soil fertility.
The humus content of soil has been accumulating over vast eons of time, both in the forests and grasslands of the world. The intervention of man in the physical world has changed and is changing many dynamic, natural systems. The continuing destruction of the forests of the world is wrecking havoc on natural cycles. Forests are very effective agents in the prevention of soil erosion and in the feeding of springs and rivers. The trees and undergrowth of the forests break up rainfall into a fine spray. The litter on the forest floor protects the soil from erosion. The residues of both plant and animal life are converted in humus, which is ultimately absorbed by the soil underneath through the action of worms, small animals and insects. Great volumes of water are stored as a result of these actions.
Grass is a very valuable factor in restricting the movement of rainwater towards the sea. Grasslands stretching for miles beneath the forested higher elevations absorb enormous quantities of water. Great quantities of humus rich soil develop under the waving plains of grass.
The over cultivation of grasslands by planting crops gradually depletes the humus content of the soil. The continual use of chemical N.P.K. fertilizers gradually depletes the soil of humus. Infinitely vast systems of life, mostly microscopic, that lives in the soil and depends on humus for their sustenance, are reduced. The crumb structure of the soil is lost; the soil is gradually deprived of oxygen making plant growth very poor.
A great percent of the continental surface of the United States is covered with grasslands. Among these grasslands are the home lawns and other lawn areas devoted to various purposes. These areas devoted to grass provide a very large environmental benefit by holding water, resisting erosion, producing oxygen and moderating environmental temperatures.
Building up the humus content of home lawns through the use of organic fertilizers will improve the activity of soil life in the creation of humus. The oxygen content of the soil will increase, stimulating healthy grass growth. The end result will be that the soil will be more permeable, better able to absorb water and ultimately more productive.Back