Show CONTROL Co ROL AND PREVENTiON OF OE EROSION ON FOREST RANGES By ARTHUR W W. SAMPSON Director Great Basin Experiment n j.- j. Forest Service Selce V It is h hardly necessary to necessary r remind re re- mind mirld the i farmer stockman r sto er-sto km n of the W West st that his prosperity d depends I i largely upon an adequate water supply for irrigation and for the production tion of ot good range forage r ge Water ample mple water wate and always more mor wat water r if is is the real necessity y of the West West the the keynote to to making the lands blossom forth into info nt w waving vin t fields of farm crops It II lit any any mountainous region where th the slopes are steep and i the precipitation tion he heavy vy floods s are i liable to occur The intimate relation re re- r relation lation that exist bet between veen th the National F Forests rests and a sustained sustain d for irrigation is generally generally generally gen gen- recognized At l least ast 8 85 percent and probably considerably consider consider- considerably ably more o of f the wat water r used for irrigating tho O acres res of Western estern lands has its origin in inthe inthe inthe the mountain of f the National Forests The most o obvious relation that exists between Forests and water water wat wat- er er is is' th the tend tendency nc of the covert cov cover r rb t to b check cheek destructive eros erosion on A Awell A Awell i well vegetated area supports support soil which has has' a high pow power r. r of ret retaining ining water and this in itself tends to stabilize the Then too t the 1 numerous s' s le leaves yes and branches Q of fh the the v vegetation g tati n prevent the rain rain from beating directly down upon t the e soil as it itO does O S in the open and this in addition to the binding effect on the soil of the plant plan roots ten tends tend s greatly to minimize the th erosion In 1914 an experiment was was initiated at t the 1 Great Basin Basi ExperIment Experiment Ex Experiment Ex- Ex Station near Ephraim Utah for the purpose of det determining deter deter- determining mining what effect heavy grazing graz graz- grazing ing as well as controlled or moderate grazing have on and erosion Two comparable areas each each embracing embracing embracing ing 10 acres were vere located at an elevation of feet the areas having ng practically y the s same slope exposure and ground cover cover Large cement tanks were were con con constructed strutted at t the the base of th these s' s se selected areas by n means ans of which it has been possible to record accurately all the water and sediment sediment sedi sedi- ment that has been carried d down wn from each rainstorm as well as from melting snow To date each each area has been grazed moderately moderately moderately mod mod- by sheep once n e e each ch s season seas seas- ason as- as on on since 19 1914 1914 4 Seeing of course f-course course is s' s believing but if f. f anyone anyone had told rne nie me that as as much ch as a car load or approximately approximately approximately pounds of air dry dirt and rock would he be e deposited from rom a ten acre area from a asing single sing e storm I J would probably be e inclined to to ask permission to examine examine examine ex- ex ex ex- amine the figures figures' for fol myself Nevertheless air dry sediment Pf of from to pounds has been depo deposited sever several l times during durin during dur dur- in ing tl six years from a single r rainstorm i 1 tOrm In such instances usually ny f 1 inc i or more more re of ofrain I rai rain ram h ba hasp f fallen Uen in a a relatively r x ly Y short hort time tim J J S Let us con coi consider sider ider for a moment what erosion of this chara character t r I I means to the forage forage forage for for- age and arid to irrigation F For r the purpose purpose of determining what hat effect the skimming off ff of the fertile surface layer ot of soil has hason hason hason on forage production as compared ed with soil of the same same type the where the surface soil has been undisturbed the two types of soil oil were car carefully fun selected and ana pl placed ced in large ir iron n jars in which wheat and alid field peas were re soWn son After th three ee months of growth it was found that the d dry y weight of the wh wheat at plant grown in the eroded or poor poor soil was 5 2 1 pounds whereas in the good g or non-eroded non soil the dry weight r Iwas w i 12 i 4 Fu Further ih i it t required re required re re- q ired Ij nearly dearly three e times time times as I much w water water ter to produce one pou pound id of dry weight eight in th the poor soil as asin asin s sin in the good soil In Inthe the case case offield offield of offield field peas the figur figures sare are in n almost al al almost most exactly the s same same me pr proportion por tion This test test demonstrated t l clearly that the upp upper few inches s of f the undisturbed d 01 or good soil is really th the life of the soil and it is of the greatest importance to to conserve conserve this upper rich layer if i if a a luxuriant foliage is s to be pr produced pro pro pro- d The effect of f a sudden runoff on on irrigation is also most ost serious erious In the first place it is impossible to make good use of water for irrigation purposes s when it gushes gush gush- es down ina in n. n a torrent in ih the sec second second se se- se- se c cond nd pl place ce the destruction which frequently follows the irrigation channels renders their upkeep very In addition to this the destruction destruct on of property is sometimes serious A sustained sustain sustain- s sustained ed uniform or flow of water such uch as is enjoyed where th the vegetation vegetation t tion on is o over er important watersheds is luxuriant nt invariably spells wealth and prosperity to the community Ode of the first steps to to prevent prevent pre prevent pre pre- vent serious erosion is to and then maintain the Forest Forest Forest For For- est l lands in the p highest hest possible state of productivity This can can best be he accomplished cc by applying applying apply apply- ing fog the deferred and rotation grazing system on lands especially especially especially ally on the steeper slopes which h have vebe been n depleted Where the watershed watershed i is particularly vital toa to toa a com community unity the construction n of f fd dams d ms as has been done 10 to such an extent t in Europe notably t bly inthe in inthe inthe the Sw Swiss ss Alps is another means of p prevention The construction tion of dams however is is expensive sive and their use use is li limited to situa situ where the de destruction is much more than average in seri ser ser- ser ser- i It is invariable in invariable vari a matter atter of f economy economy to correct correct the factor which is chiefly responsible fo for erosion before the floods become M particularly destructive tive Building Building Build- Build r ing up up p and m maintaining i ing the p plant a t cover is the cheapest and most reliable preventive measure against destructive floods a Dept Agri gri lu bulletin letin No discusses the findings at at- att the t e. e Gre Great t Basin s Experiment nt Station t ton on t the e subject of oj range preservation preservation tion and its relation to erosion control l on West Western rn g grazing lands a |