Question Using simple wording and terms could you please explain why inter-relationships between living organisms are important in organic horticulture?
Answer Dear Jenn:
A healthy soil is alive, teeming with microorganisms such as bacteria, fungi and yeast as well as larger creatures like earthworms. They depend on the availability of air, water and nutrients in the soil to live.
In return, they are the ultimate recyclers - breaking down organic matter to release nutrients for root development and plant growth. They also mix up the soil to improve aeration, texture and structure.
Plants use inorganic minerals for nutrition, whether grown in the field or in a container. Complex interactions involving weathering of rock minerals, decaying organic matter, animals, and microbes take place to form inorganic minerals in soil. Roots absorb mineral nutrients as ions in soil water. Many factors influence nutrient uptake for plants. Ions can be readily available to roots or could be "tied up" by other elements or the soil itself. Soil too high in pH (alkaline) or too low (acid) makes minerals unavailable to plants.
"Soils are populated by a multitude of microbial and invertebrate organisms, in addition to more complex animal biota. Plant roots, seeds, and fungi, are a large part of this microhabitat.
Soil microorganisms play an extensive role in the decomposition of organic matter and production of humus, cycling of nutrients and energy and elemental fixation, soil metabolism, and the production of compounds that cause soil aggregates to form. Many are in symbiotic relationships with plants and animals serving as nitrogen fixers and gut microbes. They function as a substantial part of the food web.
Among the microorganisms found in the soil are bacteria, actinomycetes, fungi, micro-algae, protozoa, nematodes, and other invertebrates (mostly arthropods).
It has been estimated that if you look at one “gram” of soil you will see the following numbers of organisms--bacteria 10 8-9 , actinomycetes 105-8 , fungi 105-6 , micro-algae 103-6 , protozoa 103-5 , nematodes 101-2 , other invertebrates 103-5 . A square meter of soil may contain 30-300 earthworms. There are more organisms in a gram of soil than there are human beings on this Earth! References: Soil Biology Guide. Dindal (ed.) 1990 John Wiley & Sons and Soil Microbial Ecology, F. Blaine Metting Jr. (ed.) 1993"
"A fertile soil is comprised of both macro- and micronutrients. Plants require both to thrive.
The macronutrients include nitrogen (N), phosphorous (P), potassium (K), calcium (Ca), magnesium (Mg) and sulfur (S). They provide the main nutrients for plants. The first three - N, P, K - are used in the largest amounts by plants, each providing specific benefits including leaf and stem growth (N), root growth (P and K), flower and fruit development (P) and overall vitality (K).
Plants need micronutrients, also called trace elements, such as iron (Fe), manganese (Mn), copper (Cu) and zinc (Zn). Their presence in very small quantities is essential for plant life. The balance and level of these micronutrients is critical as excesses are harmful to plants. Compost provides an available, balanced supply of these micronutrients. References: The Composting Council of Canada"
