2013-04-09_REVISION - M1977215 (4)

Home Browse Search

When appraising general site quality, three major factors must be taken into account. These influences are soil moisture regime, soil temperature regime, and nutrient content of the materials. All soils on the Homestake tract are placed in the Ustic moisture regime. This designation denotes general dryness, but the site has moisture available for plant growth, at least 180 days or 90 consecutive days most years. To a large extent, the length of growing season is dependent on annual soil temperature. These soils are placed in a Cryic moisture regime, which means the average soil temperature exceeds 0 ° C but is less than 8 ° C. In many respects, the limiting factor for biomass production in this locale is the cold temperatures. Isolated pH readings were taken in blocks C and F. Results ranged from 6.5 to 7.0. This pH indicates that these soils have a fairly high base saturation percentage. This means that the medium can supply exchangeable cations, especially calcium and potassium rather than hydrogen. This assumes that more nutrients are available for plant consumption, therefore, these soils are judged to have a moderate fertility rate. Nutrient tests indicate that current N -P -K status is IO -180 -200. It is important to note that although nutrients are present in sufficient amounts, they are not always available to the plants because of inadequate moisture during the growing season and consequently retarded uptake. In many instances, particularly wooded steeper slopes in the area, soils lack sufficient depth to supply nutrients to plants. Generally, the heavier textured soils derived from the Creede Formation will exceed the coarse, volcanic- derived soils in productivity potential. This is due to the fact that clay particles are capable of a very high plant nutrient storage capacity. The reservoir of nutrients in the sandier growing mediums is minimal in comparison. When these 3 factors are appraised, production - capability is considered to be moderate, at best. Both cold temperatures and dryness during critical parts of the growing season restrain production capabilities here. Soils in Area A have formed on unconsolidated landslide materials of the Creede Formation. A typical profile includes . a 3 -6" A horizon of silt loam or loam texture. Subsoils are reddish colored clay loams that lack structure and contain at least 30% coarse fragments by volume. Production in the northern end of the unit is largely limited by steep slopes and resultant shallow soils. Much of the northeastern section contains rockslides. Soil loss is negligible on these armored slopes. Since most of the mine facilities occur in this unit, rehabilitation will be confined largely to the roadway. Normal roadbank shaping, seedbed preparation, and fertilizer treatments should satisfactorily safeguard the soil resource.