Soil amendments and Fertilization- SOIL IS ALIVE!!!
Healthy soil contains millions of microorganisms per teaspoon. This, the bottom of the soil food web, supports everything else - trees, shrubs, and even grass at the top. Microorganisms consume soil nutrients, other microorganisms, decomposing organic matter, and oxygen and then poop out or die to become nutrients in more complex, usable and stable forms including humus. Humus holds nutrients and water, resists further decomposition, and can bind heavy metals. In this process sticky substances are produced that help produce soil aggregates, structure, and porosity. Macro pores hold air, the smaller ones water. As soil drains, air is pulled into these macro-pores, and that teeming beneficial underground community breathes. Oxygen in, carbon dioxide out.
These beneficial microorganisms consume and can out compete the pathological ones. Tree roots also need air pores in order to elongate. Soil compaction destroys this wonderful system, stressing plants and increasing susceptibility to disease and pests. Compaction results from regular or heavy foot traffic, riding lawn mowers, vehicular traffic, trucks, piles of building materials, etc. (See the Construction site page). The anaerobic condition that ensues suffocates most of the beneficial ensemble, and often enhances the pathological ones. Some of the ensemble, the simpler ones, are ubiquitous, recolonizing easily from the environment. Others, the more complex and specialized ones like mycorrhizae take a long, long time, or need assistance from us.
Mycorrhizae (Latin for Fungi-root) are a group of specialized fungi inhabiting tree roots that can extend their parts quickly over a large area to bring nutrients and moisture directly to these roots.
We introduce organisms, mostly bacilli and mycorrhizae, into the soil by aqueous injection, along with other soil builders and nutrients and air.
A more rigorous method is to cover the area with composted mulch, and drill through it down into the soil with an auger. This creates regular aerated columns of compost, an environment conducive to growth and is a method to revive severely stressed trees.