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<br />Most sewage sludge presently produced at the Denver sewage plant is <br />waste activated sludge, a better fertilizer than anaerobically <br />digested sludge, but is not as stable as anaerobic sludge. Its <br />odor and water content limit the demand for waste acti~~ated sludge. <br />On the other hand, air-dried anaerobically digested sludge is in <br />demand. Metro Denver Sewage District is presently in the process <br />of converting all treatment to anaerobic digestion in hopes of <br />disposing of all sludge by beneficial use as soil builder and <br />fertilizer. <br />4. Dry Poultry Waste (DPW) is an organic fertilizer, physically and <br />°o n~v-K <br />chemically similar to a 5-3-2 inorganic chemical fertilizer. The <br />recent increase in the cost of chemical fertilizer has prompted the <br />development of DPW and other fertilizer products. Research on DPW <br />is ongoing, but presently it appears that nitrogen is released to <br />the soil at a rapid rate. This characteristic, along with high <br />cost, make it less desirable as a soil building amf~ndment than <br />sewage or manure. <br />5. Sawdust and wood chips are available for use in reclamation from <br />sawmills in Fraser and Kremmling, Colorado, where they are <br />considered waste and burned at significant expense. Sawdust or <br />wood chips are equally beneficial as soil building mulches; <br />however, the decomposition of wood chips incorporated into mine <br />waste might take as long as 10 yr at high elevations. During the <br />process of decomposition, significant amounts of nitrocen are tied _ <br />up, necessitating some form of nitrogen fertilization. <br />6. Straw mulch is also a very good mulch and is similar in effect to <br />wood chips or sawdust. However, straw mulch decomposes rapidly and <br />requires incorporation in the soil to prevent loss due t:o blowing. <br />7. Chemical fertilizer is the cheapest and most available amendment. <br />At the same time, however, its longevity is short and soil-building <br />qualities nonexistent. Vegetation can be grown on tailing using <br />chemical fertilizer only, but the success rate is lower and <br />4 <br />