Characterizing Compost Teas for Biofertilization Research

Primary author: Adel Almesmari
Faculty sponsor: Lynne Carpenter-Boggs

Primary college/unit: Agricultural, Human and Natural Resource Sciences
Campus: Pullman


Compost teas (CT) have gained attention as possible alternatives or supplements to synthetic fertilizers and pesticides used in agriculture. CTs are becoming increasingly popular, and several studies have shown that CTs can provide nutrients to plants, increase soil and foliar microbial diversity, stimulate crop systemic disease resistance, and build soil structure. However, CTs are poorly studied and controlled, and vary widely in composition. For both research and practical purposes, there is need to standardize recipes for CTs with repeatable microbial and chemical characteristics. This experiment was conducted to determine the effects of compost type, recipe (additives and aeration), and brewing time on characteristics of CTs. Eight CTs were prepared by using four recipes (A, B, C, and D) with two types of compost (WSU bedding compost [Wb] and vermicompost [Ver]) or control (no compost). Each solution was characterized after 1, 3, 6, and 10 days of brewing time. CT characteristics were highly affected by the recipes and time of brewing, and minimally affected by type of compost. Recipes A and B supported high microbial populations and more soluble nutrients compared to recipes C and D. This was true with both types of compost and the controls with no compost. Microbial populations were smallest at day 1 and greatest at day 3. The study shows that CT characteristics can be well managed by recipe and brewing time. This work has potential to affect all future work on CT by describing standardized recipes and procedures for CTs with particular desired characteristics.