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s mORGANIC MATTER <br />4 organic matter levels. Eastern research -(55 <br />L ions, but sound recommendations for organic resi apphcation r <br />C.-West are only speculative .=,= <br />` "In recent years a new technique has been used success a <br />in nes in northwestern Colorado. The'method teniporar mcreas. <br />matter content of the dynamic fraction before topso stnpptng and <br />ment activities. It involves "rotoclearing =' (rofot1111ng o natt ve$eI <br />including trees (aspen up to 50 cm in diameter) (shrub- fo b and <br />into the top 40 cm of the soil profile just•prior to topso 1stnp ling ( <br />=.. communication, T. Johnson, Colorado Yampa:CoahCorniiiin t� <br />Springs, Colorado, and J. Monarch, Pittsburgh'andlMidiiva <br />pany, Denver, Colorado). Rotoclearingln`volves`pulling 425 =hors <br />3 -m wide, 9,525 -kg rototiller -like machine" through vegeta fiQftwitli� <br />- dozer. This action incorporates significant -but itnquantifedImoui <br />. ganic material into the topsoil. The inateriai rangestro i woolp:c <br />small tree stems with high C/N ratios to well- pulverizetIirapidl i d "E <br />able leguminous plants with low C/N ratios .irectreplaceme ot, - <br />of soil follows soon thereafter (less than' t 2 , -1 d <br />months), he effciirtk - and second -year revegetation has been benefieia The°effei of stoc <br />and replacing this material is unknown because the''techniqueiiaa <br />used long enough to observe revegetation effortCO3"± -"_ <br />Erosion. A primary goal of revegetation planning tai "minimize egos Reducing erosion is very important with 'tnainta;nmi'_org, <br />matter in the surface horizon. Erosion ` robs' the;surfaa lorizon <br />matter. Usually, eroded material conta 1 415 $ t ii s = <br />matter and N as undisturbed soil (4): Humus haa_ <br />therefore, is more susceptible to detachment _arid t3ansjaor ram _ -- <br />splash than to clay or quartz mineral This acconntifor tI eliigh concert -- <br />tion of organic matter in eroded materials_441 <br />Organic matter in the form of mulch - or nurse crop=residuess <br />the soil erodibility and crop management factorail i ie uni eisal =s oli <br />equation. Therefore, the higher the organie.tatter ontem z, <br />plant growth medium, the lower the erosion rat =USL -alep#afet =ei - <br />rates for two similar soils having 0 and`?1_perce un;_ <br />same management and vegetation, on:thename" stop ani rltaii <br />tion will differ by 50 percent; the lower - organ =rnat oil 1� <br />higher erosion rate (1, 88). This agrees viithibt __ ai' discus�st :474 _ <br />organic matter increasing the infiltratorcrate,a_ re.ucmgrun <br />Research regarding effects of mulching and - crop :residue =o =wi <br />water erosion have shown that relatively iow application .rates',can si <br />cantly reduce water erosion. Near Zap, -North Dakota; Li i3 <br />straw reduced erosion 93 percent on loamy topsoil relativeto plots <br />(32). In western North Dakota erosion rates on a sandy_loam topsoil; witha <br />9 percent slope on which 4 t /ha wheat straw -had: been applied,• wwre.Oi 6 <br />rovidt <br />is <br />SMITH, REDENTE, and HOOPER <br />m separated into two general <br />fraction has an' equilibrium <br />le canbe done to increase this <br />st be directed at changing the <br />tter to the site (exogenous) or <br />/N ratio as close to the target <br />lications may be necessary to <br />ous mulches have C/N ratios <br />verage soil ratios of 10:1 (4). <br />e western United States have <br />itively, areas amended with <br />s can be left fallow allowing <br />tion. But such an alternative <br />that may invade the area may <br />uld be consistent with the in- <br />ument, and continued plant <br />for plant growth, rather size - <br />3n the type of organic matter <br />:al condition of the topsoil, <br />amounts that provide some <br />ions vary considerably, but <br />Id be consistent with the in- <br />:rally, a one -time application <br />ne nutrients. Even if organic <br />, a one -time application pro - <br />are low or high in clay con- <br />n the form of straw mulch in- <br />decomposition (7), intercep- <br />o seedling development (39). <br />It in a formation of high C/N <br />an early seral stage (68). But <br />ems can be minimized (30). <br />apply mulches, wood wastes, <br />laterial should be incorporat- <br />w precipitation {<25 cm /yr) <br />ration is planting an annual <br />or disking the crop in the fall <br />I barrier to trap snow and re- <br />_ <br />Tarding permanent increases <br />3 <br />