2002-07-08_GENERAL DOCUMENTS - M2002004 (3)

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SMITH, REDENTE, and HOOPER from one typifying pedon (all . If several map units of the :cause the organic matter con - percent, one typifying pedon whether topsoil or overbur- iwth medium during reclama- . is proposed, an order -1 soil organic matter and other soil irden is proposed, an order -2 cterization to perform topsoil • is to identify topsoil stripping us topsoil stripping depth cri- c matter content should be in- Ihases (map units) of any soil uspects that the proportionate han 33 percent within any soil 4.0 percent), different phases lapped, provided the different phs and topographic or native :1d. For example, if in a culti- c aerial photography an eroded in an adjacent, less eroded, le soil series should be mapped atter content from the soil with minimum map unit size crite- iould be included as a basis for her limiting soil conditions oc- A horizon within a particular f an identifiable management, e, different phases of the soil 1. For example, a slightly more due to a greater amount of lick -A" phase. It should be y from adjacent, less concave ;uishable based on topography criteria. em is critical to the successful rid and semiarid West (21). An 207 SOIL ORGANIC MATTER important, integral part of this functional ecosystem is the process of soil organic matter formation. Hence, reestablishing the dynamic processes of soil organic matter formation may be more important than having topsoil with the optimum organic matter level. The most important input to soil or- ganic matter formation is vegetative detritus, which must be deposited on a regular basis. Vegetation and inputs of lesser importance stimulate microbial populations to predisturbance levels. Rejuvenation of microbial activity starts the active cycling of various organic compounds resulting end products of decomposition that will, in turn, be used by plants and microorganisms. As the cycles continue, soil organic matter levels and fer- tility will increase and eventually reach an equilibrium. What is the optimum level of soil organic matter in topsoil for mined land? Research has not yet identified a specific level for any one location; we believe it will even vary within a specific mine. We believe the optimum level should be the stable, baseline level. The stable level, however, varies from mine to mine and within each mine because the stable organic matter level is a function of several varying factors: texture; chemical characteris- tics; microclimate; site- specific vegetation it will support; and future slope, management, topography, and land use. Furthermore, soil organic matter may be less important than some of these factors, yet all fertile soils, includ- ing those replaced on reclaimed land, must have a minimal supply of organ- ic matter and will have a minimal supply if revegetation is successful (68). Several characteristics of soil organic matter can be quantified, but few are useful as they relate to indicating the value of the material as plant growth media. Soil organic matter in soil baseline reports should be quanti- fied on the basis of total organic C by soil series or by soil map unit rather than total organic matter. In addition, spore counts should be performed to quantify vesicular - arbuscular mycorrhiza populations; these counts will provide planning target levels. Total organic C should be determined by the modified Mebius technique (58). Although direct estimates of organic mat- ter content using the loss -on- ignition technique and a reduced ignition tem- perature (430 °C) has promise as a method for determining organic matter content, the method is not recommended because of a lack of complete evaluation of its usefulness and applicability. The sampling program should insure collection of soil from one typifying pedon —all genetic horizons —of each soil series mapped. If several map units of the same soil series exist within the permit area and are suspected of having an A horizon thickness or organic matter content variability greater than 33 percent, at a minimum one typifying pedon of each map unit should be sampled. Many species of plants that are desirable for disturbed land revegetation may be dependent on vesicular - arbuscular mycorrhiza fungi. Reduced inoc- ulum levels in disturbed soil may result in vesicular - arbuscular mycorrhiza choosing against such plants, resulting in a contribution to the establish-