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ment of nonmycorihizal plants. Experimental inoculation of revegetation
<br />species with vesicular - arbuscular mycorrhiza fungi has enhanced seedling
<br />establishment, stress tolerance, and growth of revegetation species. Thus,
<br />this inoculation_ may improve the plants' competitive ability and productiv-
<br />ity: during revegetation. Comm ercial application of vesicular - arbuscular
<br />mycorrhiza to reclaimed land, however, has not been demonstrated even
<br />though development Of commercial application methods are in progress.
<br />Gi enthe present_state, o> progress in developing commercial application
<br />methods, current reclamation goals should emphasize methods of maintain -
<br />iny inoculum leyels_byminimizing topsoil storage periods or using direct re-
<br />placement methods: { ,
<br />,Asa rule of thumb, an optimum organic matter level in the plant growth
<br />mediu a shouldbe approximately equal to baseline conditions under a to-
<br />pography_and land use similar to that proposed in the post- mining reclama-
<br />tion,plan.,,The :implicit principle of this recommendation is important.
<br />Maintenance of humusat ahigher level than surrounding undisturbed areas
<br />is not only difficult but expensive because the rate at which C is lost from
<br />the sail incr „rapidly as organic matter content increases. Likewise,
<br />Dumas, levels = lower:thansurrounding, undisturbed soils may indicate long -
<br />termYinferiontj _
<br />Where topsoil is Aped -and topsoil is in abundant supply for reclama-
<br />tion :a first-lift _stripping,of the uppermost horizon(s) having a greater per-
<br />centage of organic C (themollic epipedon) should be stockpiled separately
<br />from :lower horizons.in the profile that meet topsoil criteria. During over-
<br />burden and soil: handling phases of reclamation, the first -lift topsoil should
<br />be- replaced last creating maximum fertility in the minesoil profile.
<br />As a second. rule e of,thumb, where cultivation is the proposed post- mining
<br />land use, organic levels should be about 75 percent of unculti-
<br />vated baselineeleveketr:100 percent of cultivated baseline conditions under
<br />imilar topographic.eonditions. For example, if the pre- mining land use is
<br />rangeland and the proposed post- mining land use is cultivated cropland, op-
<br />timum topsoil levels should be 7S percent of baseline values.
<br />,; Baseline levels, of organic matter provide an estimate of what these rule-
<br />.
<br />of=thiimb levels should be and how they may vary with location. Through-
<br />out the western United States, organic matter content ranges from 0.5 to 12
<br />percent and higher.:- But_in most mining areas of the West, levels are usually
<br />to_S, percent. Intl e:dry, ,a_rid environment of the Southwest virgin soil
<br />organic matter content is -less than 1 percent, whereas organic matter levels
<br />in,the northern Gr eat Plains range from 2.5 to 6 percent. Mountainous
<br />areas in the central Rocky Mountains have organic matter levels of 2 to 12
<br />percent or higher These provide general target levels for organic matter in
<br />western mined _ rand. y, :--,_ - ett
<br />Applications o f organic matter can improve site and soil quality. Organic
<br />matter, should pot be : regarded, only as a limiting criterion of soil material
<br />SMITH, REDENTE, and HOOPER
<br />SOIL ORGANIC MATTER
<br />being evaluated for use as tl
<br />and management recommt
<br />may exist in nontopsoiled I
<br />► If the major limitatioi
<br />or sand texture, or a loamy
<br />t /ha of organic matter sho'
<br />■ If the major limitatio
<br />tion, up to 4.2 t /ha of orga
<br />20 cm of soil to increase it
<br />create an environment wilt
<br />application of Na replacen
<br />Na cation displacement.
<br />► If the slope of the rec
<br />cipitation exceeds 30 cm, or
<br />or more of organic matter
<br />conditions not limiting, to
<br />► Any area receiving al
<br />20:Y'may need :.l fertilizati
<br />► Soil areas to be strip
<br />should be given considerat
<br />► With the possible ex
<br />use of mined land is disco
<br />the organic matter loss a
<br />under this form of manag
<br />► Excessive applicatio
<br />should be avoided in any
<br />► Applications of orga
<br />of the soil.
<br />► Application of orgai
<br />medium via the use of a le
<br />the dynamic fraction any
<br />formation when moisture
<br />1. Agricultural Research Set
<br />rainfall- erosion losses fro
<br />Handbook 282. Washing
<br />2. Alexander, M. 1977. Int.
<br />Inc., New York, New Y(
<br />3. Allen, E. B., and M. F. i
<br />cular mycorrhizae follow
<br />plied Ecology 17: 139 -14
<br />4. Allison, F. E. 1973. S.
<br />Developments in soil
<br />Amsterdam, The Nether
<br />
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