Laserfiche WebLink
49 <br /> 2-KEY TO ABBREVIATIONS <br /> a. Chemical Analysis: (Tables 3, 7 Appendix B) <br /> pH - degree of acidity or alkalinity, 7=neutral, below 7=acid, <br /> above 7=alkaline; soils 5.5-8.5 are generally suitable for plant <br /> growth, O.M.=Organic Matter, E.C.=Measure of salinity by electrical <br /> conductance; (No.)= EC x 103 millimhos/cmt is scale used; Example: <br /> 4.0 is equivalent to about 2500 parts per million (pgm) of salts <br /> and is a level that restricts growth of the more sensitive crop <br /> and native plants. An EC x 103 value of 16 would be tolerated <br /> only by the most salt-resistent plants such as kochia or distichlis <br /> (salt grass) . <br /> ESP - exchangeable sodium percentage. SAR=Sodium absorption ratio- <br /> a measure of tendency for sodium cations to be absorbed on clays <br /> replacing other basic cations such as calcium. SAR values over 15 <br /> are considered unsuitable for most crop and pasture species. <br /> Elements -Ca=Calcium, Mg=magnesium, Na=sodium, CaCO3=calcium <br /> carbonate (pure lime) , meq/l=milliequivalents per liter, <br /> SAT--Saturation percentage equals percent by weight of water held <br /> by a soil at saturation. <br /> b. Soil Surveys - SCS Form 232 Appendix A <br /> Source: U.S. Dept. Agriculture Handbook 18 <br /> Horizon - layers approximately parallel to surface with character- <br /> istics produced by soil-forming processes. A simple key for the <br /> Nucla soil survey is Al-Mineral horizons, formed or at the surface, <br /> in which humified organic matter is intimately associated with <br /> mineral fraction. <br /> A2 - lighter colored layer associated with surface but lower in <br /> organic matter, generally well-leached of minerals. <br /> AP - surface layer disturbed by cultivation or pasturing; may <br /> include some of lower horizons by mixing. <br /> B - (general) horizon or horizons underlying A horizon with some <br /> evidence of mineral change such as accumulation of calcium <br /> carbonates, higher clay contents, change in structural aggregates, <br />