Laserfiche WebLink
<br />5.0 SOIL RECONSTRUCTION MATERIAL FOR DRASTICALLY DISTURBED LAND <br />• <br />5.1 METHOD OF EVALUATION <br />~ An SCS guideline for evaluating soil as a plant growth media is presented in Table <br />5-1. The table includes SAR, EC, toxic materials, pH, available water capacity, <br />erosion factor, wind erosion group, texture, and percent coarse fragments. <br />~ When the soil materials are properly used in reconstruction, a good rating means <br />vegetation is relatively easy to establish and maintain, the surface is stable and <br />resists erosion, and the reconstructed soil has good potential productivity. Mat- <br />erial rated fair can be vegetated and stabilized by modifying one or more proper- <br />~ ties. Top dressing with better material or application of soil amendments may be <br />necessary for satisfactory performance. Material rated poor has such severe prob- <br />lems that re vegetation and stabilization is very difficult and costly. Top dressing <br />with better material is necessary to establish and maintain vegetation. <br />• <br />Excessive amounts of substances that restrict plant growth, such as sodium and salt, <br />create problems in establishing vegetation, and therefore also influence erosion and <br />the stability of the surface. Other substances such as selenium, boron, and molyb- <br />~ denum get into the food chain and are toxic to animals that eat the vegetation. If <br />relatively high levels of toxic substances are in the reconstruction material, the <br />material should be rated poor. <br />~ Vegetation is difficult to establish on soils with high pH. High sodium adsorption <br />ratio indicates potential instability and water transmission problems. <br />Available water capacity also is important in establishing vegetation. Soils with <br />~ low available water capacity may require irrigation for establishment of vegeta- <br />tion. Available water capacity has been estimated based on saturation percent. <br />The stability of the soft depends upon its erodibility by water and wind and its <br />~ strength. Water erodibility is indicated by the K factor; wind erodibility is rated <br />~ - 13 - <br />