Soil Tests

The solubility and mobility of chloride in soil is similar to nitrate, and soil sampling depths for chloride, like nitrate, are typically greater than for less mobile nutrients. Although the best soil sampling depth may vary depending on the rooting depth of the crop, a sampling to a depth of 60 cm has been found to be a good indicator of chloride availability to potato (58) and to spring wheat (2). Crops, such as sugar beet and winter wheat with deeper rooting depths, may need a deeper sampling depth (2,37).

Because chloride is highly soluble and only weakly adsorbed, it can be extracted from soil with water or any dilute electrolyte. The choice of extractant may depend on the analytical method employed to determine the concentration of chloride in the extract. Methods of analysis for quantifying extractable chloride may include colorimetric, potentiometric, or chromatographic procedures (69). Precautions should be taken to avoid potential sources of chloride contamination (e.g., perspiration, soil sample containers, dust, glassware, water) during soil sampling and laboratory analysis.