OCR Text |
Show mature, there will be in due course a reversal of the present trend. Skyrocketing lumber prices indicate the seriousness of the situation, as does the scarcity of high-quality lumber that has existed in recent years. Farm land has deteriorated to an equally seri- ous degree. Figures are not available to estab- lish a trend, or even to determine whether we are gaining or losing ground in the conservation of topsoil. But it is the opinion of the Soil Con- servation Service that each year the equivalent of half a million acres is permanently lost to pro- duction, and in addition, a quarter of our crop- land is in critical danger of losing its topsoil, while another quarter is eroding rapidly. Erosion is only one measure of damage or loss. While there are no general survey data, spot data suggest that there is an even greater loss of essen- tial plant nutrients contained in the soil. In 1945 a study was made for the Federal Re- serve Bank of St. Louis, to determine the loss of plant nutrients and topsoil in the Corn Belt. It indicated that each year 6 billion dollars worth of nitrogen, potash, and phosphoric acid are lost from the soil through the harvesting of crops, of which less than a sixth is replaced. Other authorities believe that less than a tenth is re- placed. In addition, according to the 1945 study, 3 times as much nitrogen, 6 times as much phosphorus, and more than 60 times as much potash are annually removed from the soil through erosion and leaching. The loss of plant nutrients may show itself in reduced yields. The volume of crop yields is still the accepted yardstick of productivity. But a growing body of scientific opinion, backed by much experimental data, holds that volume of yield is often misleading, since crops of equal size and weight may differ markedly in nutritive value. It is possible, according to some scien- tists, that the nutritive value of crops can decline substantially, even though there is no apparent loss of topsoil or reduction in crop yields. Data on. grass lands are scarce, but the de- terioration of the range lands-an important part of our livestock economy-is so well known as to require little documentation. Deterioration of forest, crop, and range land results in serious sediment pollution of streams and sedimentation of channels, reservoirs, and harbors. It also contributes in some areas to in- creased flood damage, both through increases in peak flow and silt load. In many areas of the country, too, soil denudation and erosion may have hindered the infiltration of water into ground water reservoirs. The function of watershed management is comparable to the maintenance and improve- ment of railroad or industrial facilities. It makes continued production possible, but it also makes possible increases in output. Delaying the institution of watershed management measures has already resulted in widespread damage to re- sources, and has in some areas laid the Nation open to the threat that the damage will proceed so far as to become irreversible. Yet the Nation is faced with steadily increas- ing requirements not only for food but for all as- pects of water and land use. Agricultural pro- duction, industrial and municipal use, recrea- tion requirements, power, transportation-all these needs will grow as population grows over the next decades. They will be met only as mul- tiple-purpose programs for regional development are formulated and put into operation. Water- shed management constitutes a fundamental part of such programs. The Community Watershed What is a watershed? Technically it is the land area which contributes to the flow of a stream. But the land area which contributes to the flow of a brook or creek also swells the larger stream which the brook or creek feeds. In order to define a watershed or set its bound- aries it is necessary to define the stream. It may be as small as the sloping pastures which drain into a local Turkey Creek, or it may be as large as the combined valleys which contribute to the Mississippi River System, stretching from the Alleghenies to the Rockies and from the Ca- nadian border to the Gulf of Mexico. Conservationists have urged that small, rather than large, watersheds be considered in water- 124 |