Many soils have a bad habit of holding on to phosphorus.
For farmers, this can mean money locked up in the soil. Where plants are unable to use
phosphorus once it is bound to the soil particles, there are special photosynthetic
and other microbes whose job it is to release phosphorus and make it available in a soluble form.
In a healthy soil environment, these microbes outsource the manufacture of
energised phosphorus compounds for plants. There is a fascinating community effort
which goes on below ground in healthy soil, which keeps phosphorus in play in a
pool which plants and other microbes can draw on.
Depending on how the soil is looked after, the community of organisms which
keep phosphorus available either increases or diminishes. In most farmed soils, these organisms now are much lower in population than they once were.
Keeping soil biology healthy is an integral part of making phosphorus available for plant growth. Plants cant source enough phosphorus or enough energy on their own. They need the community effort below the soil to manage both the supply of phosphorus needed to make sugars, and the supply of the energy transport compounds (which contain phosphorus) needed to convert light energy into sugars.
Soil communities including photosynthetic bacteria recycle phosphorus continually.
When they are happy, we need to add less phosphorus: When they aren't working, everything stops.