Although tall fescue and other species were planted primarily to stabilize minespoils to prevent erosion, the interaction of grasses with the overburden materials also is involved in minesoil development. Physical and chemical interactions of roots and senescent top growth can contribute significantly to development of beneficial topsoil properties. Soil organic matter content, including organic C and N, along with aggregate stability, bulk density, water-holding capacity, and nutrient availability have been noted as key indicators of soil quality (Karlen and Stott, 1994). These properties are important for sustaining plant growth and cycling nutrients.
Organic wastes, including manures, crop residues, and sewage sludge have been applied to improve the physical and chemical properties of disturbed soils. Plots overseeded with tall fescue and hybrid pine (Pinus rigida Mill. ´ P. taeda L.) had equivalent soil organic matter and N concentrations 16 yr later whether or not they had received organic amendments. Soil organic matter enhancements in the untreated plots resulted from the above- and below-ground biomass contributions from the vegetation (Bendfeldt et al., 2001). Shukla et al. (2004) demonstrated that stimulation of above- and below-ground biomass production by fertilizer application was sufficient to cause significant increases in soil organic C, resulting in a decrease in bulk density after 20 yr of tall fescue growth.
Grasses have long been known to improve soil structure by increasing the formation of water-stable aggregates (Wilson, 1957). The importance of water-stable aggregates to soil physical properties is related to the formation of micro- and macropores, which are essential for aeration and water infiltration. Formation of aggregates is viewed as a complex process whereby small soil particles are cemented together by humic materials, and then these microaggregates are bound together into macroaggregates, which are held together by microbial and plant polysaccharides (Tisdall and Oades, 1982). The importance of grasses in this aggregation process was explored by Franzluebbers et al. (2000) on a tall fescue-bermudagrass [Cynodon dactylon (L.) Pers.] pasture in Georgia. They found that soil aggregate formation and stability under pasture were greater than or equal to those under conservation tillage cropping or forestland. It is evident that tall fescue is a critical component in the development and maintenance of soil physical and chemical properties.
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