The chemical, physical, and biological conditions of soil and growing media can be substantively improved by the addition of compost. Compost contains many plant essential nutrients (e.g. N, P, and K) and can also be a source of organic matter. However, concerns persist over composts with a high concentration of soluble salts and their effects on soil fertility, plant growth, and yields. Soluble salts refer to soluble ions such as Ca²⁺, K⁺, Mg²⁺, and Na⁺ in compost and are measured indirectly and cumulatively through electrical conductivity (EC). Specifically, compost salinity is commonly measured using a method referred to as EC₅ whereas soils are measured using an EC_e. The use of a variety of non-standardized methodologies often make interpreting results between studies difficult. A compost with an EC₅ >5 dS m⁻¹ could be the result of high concentrations of Na⁺ or other ions, which can be detrimental to plants due to their ability to accumulate in plant tissue and interfere with root uptake of water. Thus, reducing soluble salts, specifically Na⁺ and Cl⁻ in composts is of high importance. Other soluble salts present in compost (e.g. K⁺ and Ca²⁺) are mineral nutrients required for plant growth and can aid in reducing soil sodicity. In appropriate proportions, quality compost with a high EC₅ mixed with soil or media can enhance plant growth and yields. Composts with a high EC₅ are adept at aiding in soil remediation by facilitating soil particle flocculation, helping leach Na⁺ deeper into the soil profile and raising soil cation exchange capacity in support of increased soil fertility. Labeling composts and developing appropriate application methods could allay concerns associated with composts where EC₅ > 5 dS m⁻¹and promote compost use and sustainable farming practices.

Quantification of heavy and trace metal contamination in soil can be arduous, requiring the use of lengthy and intricate extraction procedures which may or may not give reliable results. Of the many procedures in publication, some are designed to operate within specific parameters while others are designed for more broad application. Most procedures have been modified since their inception which creates ambiguity as to which procedure is most acceptable in a given situation. For this study, the Tessier, Community Bureau of Reference (BCR), Short, Galán, and Geological Society of Canada (GCS) procedures were examined to clarify benefits and limitations of each. Modifications of the Tessier, BCR, and GCS procedures were also examined. The efficacy of these procedures is addressed by looking at the soils used in each procedure, the limitations, applications, and future of sequential extraction.