Compost teas are a small but potentiall very significant field in supporting plants and soil. Certain organistaions really stand out globally. There are rather a lot of references in my book which may obscure the keys players listed below.
USDA The United States Department of Agriculture. They were very helpful and supportive with no gain to themselves other than promoting organic farming and good practice. The Soil Test Kits were particularly useful as was the ‘soil triangle‘ which is depicted in ‘Compost Teas’ and was used to help growers get a insight into soil texture.
Getting an insight into what your soils are like helps when making amendments. You may be low on an essential element, or your soil may not have the best properties for what you want to grow.