Repairing soil Mother Nature's way
Source Dr Elaine Ingham
Kununurra cropping WA
The soil food web is a group of organisms ranging in size from bacteria, to fungi (the largest organisms on the planet), and including protozoa, nematodes, micro arthropods, worms and beetles. The food web improves soil structure by binding pieces of soil (clay, sand, silt, organic matter, roots) together and by building airways and passageways through the soil. Unrestrained movement of air and water are vital to maintain a healthy plant and the soil food web itself. While it seems contradictory, good soil structure allows water to drain from too wet soil and aids soil to hold water when it starts to dry out.
When considering living organisms you should picture that they all eat, excrete and, in turn, are food for something else therefore these processes can be said to be cyclical in nature. Bacteria and fungi feed on plant residues and in the process break them down and capture the nutrients (e.g. nitrogen, calcium, iron, potassium, phosphorus, etc.) in their bodies. Their bodies are glued and bound to soil particles, preventing them from being lost through leaching. The nutrients bound in the bacteria and fungi are not available to plants until protozoa, nematodes, small micro arthropods, and earthworms consume the bacteria and fungi. These creatures complete the cycle by releasing these nutrients in plant available forms. Plants excrete foods from their roots which bacteria and fungi thrive on. Many of these organisms are beneficial species that inturn protect the roots from pathogen and pest attack.
Throughout this complex web of interactions the organisms also produce hormones that plants need to absorb and some that break down pollutants in the soil. The soil food web protects all plant surfaces from disease-causing organisms and other pests, often by out-competing them for food, and sometimes simply by eating them. Also, by occupying the plant surfaces, they ensure pathogens cannot gain access. At other times they perform a similar function by altering the soil conditions so that the disease-organisms cannot thrive.
So many of the practices we have adopted in modern agriculture production have actually damaged the natural processes by destroying these beneficial organisms that are found in the soil and on plant surfaces. The goal was to destroy specific pathogen and pest organisms through the use of toxic chemicals but in doing so we have also destroyed the beneficial, protective organisms that existed. Over time, disease-causing organisms have developed immunities to these over-used chemicals and now thrive, continuing to infect crops but in greater numbers. It is not surprising that pests and diseases are now almost impossible to control after 30 to 50 years of chemical warfare has been waged against the beneficial organisms in soil and thereby upsetting nature’s balance.
How do you fix the problem?