Bat guano in powder form is less soluble than liked. When applied as top soil it breaks down slowly and does not supply a fast and reliable source. Really it has to be applied at the very beginning of the grow to start having a effect once flower begins. Sort of acting like time released fertilizers. But the rate depends on the quality of soil used and the source of phosphorus.
The process by which this breakdown works is by the natural micro organisms in the soil, much in the same way true organic soils are made.
Teas and other processes work by speeding up this process of composting. Breaking down the chemicals into its more soluble constituents. By supplying the right conditions and ingredients the process can be accelerated and provide a soluble source of liquid fertilizer. Theres also the added benefit of the micro organisms that are said to help with plant health and diseases.
Now to turn things around
Currently there is not enough sufficient evidence to prove the benefit of compost teas. Theres a good theory behind it but theres a bit that goes against it too.
Regular soil compost does not contain a large amount of the focused NPK we chase. Infact of the most common types used today, the typical analysis of nutrients is quite low compared to regular fertilizers available. Compost is a relatively slow process that will last for years if left. This means that soil provides a very small readily available source of nutrients but a large long term source. Its commonly known how difficult it is to have nutrient toxicity with grows because of this very principle.
Organic soil just describes its material source type. Technically "organic" can be used to describe different types of things, food, mineral sources, manure, soil etc. But at the end of the day, they are all chemicals and the plants live off these non living sources of chemical elements. What matters is what form these chemicals are in. What i am getting at is that you might be better off sourcing fertilizer that has been processed in a more solible form.
http://www.extension.umn.edu/agriculture/nutrient-management/phosphorus/the-nature-of-phosphorus/
This article describes the chemical processes of phosphorus and how it relates to resource availability
to plants. This aspect is similar to other elements but is more impacting on phosphorus so makes it harder for this mineral to be processed.
http://www.gardenmyths.com/tag/compost-tea/
This website has good information on current science and misconceptions in todays understandings.
