2002-07-08_GENERAL DOCUMENTS - M2002004 (4)

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Soil Sampling COLORADO SCHOOL OF MINES RESEARCH INSTITUTE 9 In plots where the potential existed for soluble constituents in the spoil to migrate into the overlying soil, soil samples were taken at periodic time intervals. In most cases, an auger was used to extract the samples. Methods of sample preparation and analysis followed those previously described. Temperature Soil and spoil temperatures were measured during the 1979, 1980, and 1981 growing seasons. A dial thermometer with stainless steel probe was inserted 5 -cm deep into the plant rooting zone in spoil and in soil (where soil depth was approximately 152 cm). Efforts were made to minimize the influence of plant shading on the two sets of readings. Three replicated measurements of tempera ture were made for each growth medium. Plant Tissue Analysis In July of 1978 and June of 1979, crested wheatgrass heads were collected from all plots which had been in existence for at least two growing seasons. In May of 1980, crested wheatgrass leaves were collected. Plants samples were o- lected where the growth medium was composed entirely of spoil and where it c w composed of 152 cm of soil underlain by spoil. Collection dates were selected to cover the maximum grazing period of this species. All plant samples were washed in water immediately after collection and s ubsequently air - dried. In the labora- tory, plants were ground in a Wiley mill to pass a 20 -mesh screen. Analytical techniques utilized standard methods as much as possible. Phos- phorus was determined colorimetrically on a solution prepared by wet /dry aching in the presence of Mg(NO while boron was determined colorimetrically on plant material which was first roasted in the presence of CaO and the residue dissolved in HC1 (Richards, 1954). Nitrogen was determined using the conven- tional Kjeldahl method. The remaining elements were determined on plant mate- rial which was first dry ached followed by digestion with C1, and HP. Elemental concentrations were determined using atomic absorption HNO3, � etry At selected locations, plants were also collected from small subplots estab- lished in undisturbed soil. These subplots were located in areas that were to remain undisturbed for the life of the mine, according to the mine personnel. At the time of main plot establishment at the Dave Johnston, Cordero Wyodak, and Westmoreland mines, an undisturbed area approximately 3 by�3 m in size was ferti- lized, rototilled, and planted to crested wheatgrass using the same methods as previously described for the main plot. Plants were collected and analyzed following the above procedures. DATA REDUCTION AND STATISTICAL TECHNIQUES The data from plots with similar spoil traits and similar production response patterns to soil depth were combined to give an average res ponse pat- tern. Two methods were used to determine the average response • an arithmetic mean and a scaled mean. The scaled mean (expressed as percentage of the maximum production) was determined by finding the maximum production for an individual strip within a given plot, setting this production equal to 1.0, an d adjusting