Bacteria in the Soil

Many chemical and biological processes are constantly taking place within soil.

Chemical processes include the breakdown of mineral compounds from rock debris until they become soluble.

Biological changes occur in the soil as the result of organic matter being added to the soil.

This organic matter can include animal droppings, falling leaves and decaying vegetation.

It can also include manure that is added to the soil.

Organic material in the soil quickly changes to humus, a dark-colored substance.

Humus is then broken down into water, nitric acid and carbonic acid.

Soil bacteria, tiny microorganisms in the soil, break down the organic material.

In cultivated soil, these bacteria can be found throughout the soil.

Soil that does not contain soil bacteria is sterile.

Four million bacteria can inhabit one cubic inch of cultivated soil.

These bacteria are universally distributed throughout cultivated soil; any soil in which they are not present would be sterile.

The number of soil bacteria decrease deeper in the soil.

There are very few bacteria in subsoil.

This is why subsoil is sterile when it is first moved to the surface, before there has been enough time for deep cultivation to make it suitable for bacteria.

Soil bacteria are most active when the temperature is 65 degrees Fahrenheit.

They are not active at all when the temperature is above 100 degrees Fahrenheit or when it is below 10 degrees Fahrenheit.

Soil bacteria require moist, warm, well-aerated soil.

Lime should be added to soil to neutralize acids that soil bacteria produce.

Some bacteria have symbiotic relationships with leguminous plants (legumes), such as beans, peas, tares and clovers.

Soil bacteria form colonies on nodules that can be found on the roots of these plants.

Some cultivators will grow legumes and then turn them over, to be used as green manure.

This will add both humus and a large amount of nitrogen to the soil.