The nutritional needs of the soil in your garden can vary widely depending on the seasons and the character of each member of its microbial community. Organic amendments can be helpful to that community if applied in a way that is attentive to both its particular and evolving needs. Some microorganisms, so they say, remain dormant until they are called upon to digest available nutrients. Others always seem to have a healthy appetite.
Then there are the soil organisms, like fungi, who act as essential food-service providers. They will disperse themselves throughout the soil community binding aggregates together, assisting with air and moisture retention, creating pathways for the bacteria that will serve as food sources for the microorganisms that degrade organic matter to the point where its nutrients become available to a plant through its roots.
Timing the application of organic soil amendments helps support both plant vitality and soil ecology. Adding small doses of soil amendments such as Compost Tea, for example, in concert with the natural rythms of nutrient surfeit and deficit in the soil, not only makes those amendments more effective, but it also means they will need to be applied less frequently. This not only saves the gardener money, it also encourages healthy plant-soil-microbe interactions and respects the biodiversity of the surrounding microbial landscape.