Original site contours may be reestablished. If topsoil was 

 stripped and separately stored, it is replaced. Natural processes 

 may be relied upon to reestablish ground cover or, if revegetation 

 is conducted commercially, available seeds of hardy, very adaptable 

 grasses, such as bermuda grass ( Cynodon dactyl on ), are sown on dis- 

 turbed soils. Fertilization, mulching, and final top dressing may 

 occur. Vehicles generally exit after distributing the seed and 

 dressing the site. 



2. Primary ecological alterations 



2.1 Increase in soil structure due to grading, filling, and plowing 



2.2 Decrease in soil toxicants due to removal of oil-, brine-, and 

 mud-contaminated soils 



2.3 Increase in available nutrients with fertilization 



2.4 Increase producer biomass by reseeding or replanting 



3. Attribute alterations 



Procedures that reestablish soil structure damaged by construction 

 and operational activities are most beneficial for restoring site 

 vegetation. Grading, plowing, and discing fragment the soil crust 

 and increase water permeability and infiltration rates of the 

 surface soil; simultaneously, surface-water runoff and sediment 

 transport into adjacent areas are reduced. Micropore water and soil 

 air concentrations increase because of improved soil porosity, 

 thereby enhancing soil environment for plant establishment. Soil 

 moisture not only provides necessary water for the plant, but may 

 also moderate the extreme effects of soil heat and soil salt 

 content. 



Replacement of leached and eroded nutrients (through fertilization) 

 and removal of toxic soil materials (brine, petrochemical wastes, 

 and drilling substances) speed natural recovery processes, enabling 

 establishment of more complex plant assemblages without requiring 

 preceding serai stages to develop necessary soil conditions. Fertil- 

 ization has the greatest potential for long-term benefits by 

 improving soil structure, increasing biological activity in litter 

 and soil, balancing soil nutrient status, and reducing mobility of 

 toxic elements. Fertilizers may speed cycling of nutrients by 

 mobilizing anions and cations if biomass exists that can capture 

 them. However, if not captured, the more mobile ions may leak to 

 shallow groundwater aquifers, drainage ditches, streams, and 

 marshes. 



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