Assessing Compost Quality for Agriculture

Abstract

Composts are widely used as organic amendments to add organic matter and nutrients to soils and are also sometimes used as mulches to control pests and conserve water. Compost quality can be evaluated through laboratory analysis, but the measurable properties used to evaluate composts are different from those used to describe the soils to which they are added. Parameters such as the carbon-to-nitrogen (C:N) ratio, organic matter content, salinity, total nitrogen, total phosphorus, stability, phytotoxicity, pH, maturity, boron, chloride, sodium, particle sizes, heavy metal concentration, and pathogen concentrations are factors to evaluate when you are comparing available compost products. This publication describes each of these measures and proposes reasonable limits for five common types of compost application, including use as a soil amendment for strawberries, canning tomatoes, and lettuce as well as mulch use for grapes and avocados. A new estimation method will also help you predict the short-term influence of composts on soil salinity.