| Resumo: |
The largest Brazilian coal mine is located in the municipality of Candiota, Rio Grande do Sul state. Carbon seams lie near the surface around 10 to 25 meters deep, it can be mined open-pit. This mining method uses a dragline, a large machine for removing carbon, it involves changes in topography, vegetation and hydrological regime of the area. Density, porosity and water retention are directly affected. The major change of constructed soil physical attributes comes from removal of layers of original soil and deposition on the regeneration areas. Excessive machinery traffic during soil construction causes compaction of the area, it makes difficult water infiltration into soil profile facilitating water erosion, and inhibiting the vegetation of the area. The use of soil uncompressed plants is an important strategy on recovering soil structural quality. The knowledge of physical parameters as density and aggregation of constructed soils in mining areas must be considered of great importance for evaluating physical attributes since it can indicates changes in porosity, degree of compaction, root penetration, and water and air permeability. Mechanical parameters as pre- consolidation pressure and compression index can indicate soil bearing capacity. The general objective of the work was analyze the potential of different cover crops on recovery of coal mining degraded areas, by determining physicmechanical parameters of the constructed soil over time. Treatments with single plants established in October-November, 2007 were analyzed T1- Capim vaquero (Cynodon dactilon), T2 - Braquiaria brizanta (Brachiaria brizantha), T3 - Tanzânia (Panicum maximun), T4 - Braquiaria humidícola (Brachiaria humidicola), T7 - Hemartria (Hemarthria altissima), T8 - Grama Tifton (Cynodon dactilon). Constructed soil without cover crops was used as a control SCSP in order to observe the action of plants on constructed soil attributes recovery. As general conclusions we can state that because of little time for establishing the experiment, the cover crop had incipient action on improvement of physical attributes, but when compared with control presented highest density and porosity, DPM, and percentage of macroaggregates, highlighting Brachiaria. |
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