Laserfiche WebLink
  <br />1  <br />  <br />  <br />2.0 FIELD COMPOSITION AND SALINITY TOLERANCES <br />In June of 2021, Cedar Creek traveled to the irrigated fields to evaluate the plant composition of <br />the irrigated fields. As defined on Table 1, Cedar Creek subdivided the irrigated fields into 11 <br />subparts based on dominant composition. The dominant species observed were smooth brome <br />(Bromus inermis), alfalfa (Medicago sativa), and tall fescue (Festuca arundinacea) along with <br />other less dominant pasture grasses and forbs. None of the fields are managed monocultures <br />(e.g. alfalfa fields). Rather, the fields are typically comprised of both alfalfa and pasture grasses <br />in varying dominances. <br />The ability of the solution to carry a current is called electrical conductivity (EC). EC is measured <br />in deci-Siemens per meter (dS/m). The salinity tolerance (the EC where crops yield begin to <br />diminish) of dominant species on each field were determined using Colorado State University <br />Extension fact sheets 0.503 - Managing Saline Soils and 7.227 - Growing Turf on Salt-Affected <br />Sites. Pettygrove and Asano (1985) indicate that yield reductions for moderately sensitive crops <br />could be expected to result from irrigation water having conductivities between 0.75 and 2.0 <br />dS/m, while the threshold for moderately tolerant species would range between 2.1 and 4.0 dS/m. <br />For tolerant crops, the threshold range would be 4.0 to 6.5 dS/m. The authors indicate that, for <br />salt sensitive species, irrigation water threshold level would be reached at EC levels below 0.75 <br />dS/m. Table 1 displays the dominant species, relative composition, species salinity tolerance using <br />EC (dS/m), divisions for classifying crop tolerance to salinity (Pettygrove and Asano 1985), and <br />the field subpart salinity tolerance using electrical conductivity (dS/m). <br />