poussecafé

Poussecafé is the solid residue left after brewing coffee. Also known as coffee grounds, it consists mainly of spent ground coffee beans that have released most of their soluble compounds. Freshly prepared grounds are moist and retain a strong coffee aroma, which diminishes over time as they dry and oxidize.

Composition and properties: Poussecafé is rich in organic matter and nitrogen, making it valuable as a soil amendment in gardening and farming. It also contains trace minerals such as potassium and phosphorus, along with caffeine and polyphenols. The pH of used grounds tends to be slightly acidic, though the precise value depends on the coffee origin and brewing method. Stored properly, grounds can be composted or mulched; improper storage can lead to mold growth or unpleasant odors.

Uses: In gardening, poussecafé is commonly added to compost or directly used as mulch in moderate amounts. It can improve soil texture, support moisture retention, and contribute nitrogen to the soil. It is often considered a green compost material and should be balanced with carbon-rich materials. Some gardeners apply grounds around acid-loving plants, such as blueberries, but excessive usage can alter soil chemistry. In households, dried grounds are used as a mild abrasive cleaner, a deodorizer, and in certain crafts or cosmetic applications.

Environmental impact: Recycling coffee grounds reduces kitchen waste and can enrich soil when composted. Improper disposal—such as dumping large quantities into water bodies or allowing damp piles to dominate—can create odor or mold issues.

Safety and considerations: Use grounds in moderation and avoid thick, compacted applications. Store kept grounds in a dry, ventilated container to prevent mold. Grounds may carry residual caffeine and other compounds that can affect sensitive plants if overused.