Show a u ROTATION GRAZING 1 s By Dy Arthur W W. S Sampson It Is hardly necessary to remind tho the farmer stockman of the west wesl that his prosperity depends largely upon an adequate water supply for lor irrigation and for the production of good range forage Corage Water Tater ample water and always more water Is the thereal thereal thereal real necessity of the west the keynote keynote key key- note not to making the lands blossom forth Into waving fields of f farm crops In an any mountainous region where the slopes are steep and the precipitation heavy floods are liable to occur The Intimate relation that exists between the national forests and a sustained for irrigation irrigation gatlon gation is generally recognized At least east 85 per cent and probably considerably considerably considerably con con- more of the water used for Irrigating the acres of western lands has its origin In the mountains s of the national forests The most obvious relation that exists between forests and water is the tendency of ot the cover to check destructive erosion A well vegetated vegetated vegetated vege vege- area supports soil soli which has a high power of retaining water and this In itself tends to stabilize the Then too the numerous numerous numerous numer numer- ous leaves and branches of the vegetation vegetation prevent the rain from beating beating beat- beat ing ng directly upon the soil as it does doesn In n the open and this In addition to the he binding effect on tho soil soli of the plant roots tend greatly to minimize erosion In 1914 an experiment was Initiated initiated initiated at the Great Basin Dasin experiment station near Ephraim Utah for the purpose of determining what effect heavy grazing as well as controlled or moderate grazing have on stream flow and erosion Two comparable areas each embracing ten acres were located at an elevation of 10 i feet the areas having practically practical- practical I ly y the same slope exposure and round ground cover Large cement tanks were constructed at the base of ot i I these selected areas by means of which it has been possible to record accurately all the water and sediment sediment sediment sedi sedi- ment that has been c carried down from each rainstorm as well as from melting snow To date each area has been grazed moderately by sheep once each season since 1914 Seeing of course is believing but If anyone had told me that as much as a car load or approximately approximate approximate- ly y pounds of dry air-dry dirt and rock would bo be deposited from a ten acre area from a single storm I would probably be inclined to ask permission to examine the figures for Cor or myself Nevertheless dry air sediment of from to pounds has been deposited several times Imes during the six years from a single Ingle rainstorm In such Instances usually a half Inch or more of oC mm rain has fallen in a relatively short shon time Ume Let us consider for a moment what erosion of this character means to the production of forage and to Ir Ir- Ir For the purpose of determining determining determining deter deter- mining what effect the skimming oft off of tho the fertile surface layer of soil has on forage production as compared com cw- compared pared with soil of ot the same type where th the surface soil has been undisturbed undisturbed undisturbed un un- disturbed the two types of soil were carefully selected and placed In large iron jars in which wheat and field fieldI I peas liens were grown After three months of growth It was found that the dry weight of the wheat plant grown In the eroded or poor soil as 5 2 1 pounds whereas where where- as In the good or non-eroded non soil tho the dry weight was 12 2 Further it required nearly three times as much water to pr produce duce one pound of dry weight in the poor soil as In the good soil In tho the case of field peas the figures are in almost exactly tho the same proportion This test demonstrated demonstrated demonstrated demon demon- clearly that the upper few Inches of the undisturbed or gooc good goodsoil goodsoil soil is really the life lite of the soil soli and it is of the greatest importance to conserve conservo this upper rich layer if a I luxuriant forage crop is to be pro pro- The effect of the sudden runoff on irrigation is also most serious In Inthe Inthe Inthe the first place it is impossible to tomake tomake tomake make good use of water for Irrigation irrIgation irrigation tion purposes when it gushes down downIn In a torrent In the second place the destruction which frequently follows to the irrigation channels renders their upkeep very expensive In addition to this the destruction des destruction true true- tion of property is sometimes very serious A sustained or uniform flow of water such as Is enjoyed where the vegetation over important import import- ant watersheds as luxuriant invariably Invariably inva Inva- spells wealth and prosperity to I Ithe I the community One of the first steps to prevent serious erosion is to am and then maintain the forest lands lauds in the highest possible state of ty This can best be accomplished accomplish by br grazing system on lands especially especially especially espe espe- on the steeper slopes which have been depleted Where the watershed is particularly vital to a community the construction o of dams as has been done to such an extent in Europe notably in the Swiss Alps is another means of pre pre- The construction means o or prevention The construction o of dams however is expensive am and their use is limited to situations where the destruction to personal persona and other property is much more than average in seriousness I It is invariably a matter of economy economy my ray to correct the factor which is chiefly responsible for erosion before before before be be- fore the floods become particularly destructive Building up uP and maintaining maintaining main main- the plant cover is the cheapest cheap cheap- est and most reliable preventive measure against destructive floods Department of Agriculture bulletin bulletin bulletin bulle bulle- tin No discusses the findings a athe at atthe atthe the Great Basin experiment station on the subject of range preservation and its relation to erosion control contro on western grazing lands |