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BALANCED SOILS
  
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SOIL BIOLOGY
Biology is an intrinsic part of the unique ecosystem that exists in the soil.
Each component of the soil has a specific job and all are key players to the function
and the efficiency of this system. By creating an environment that promotes the biology's
existence, by providing food, and by adopting farming practices that are good for the environment,
wonderful things start to occur.
Biology determines quality – the mineral content of the soil and its physical structure
are important for the plants well-being, but it is the life in the soil that powers its cycles
and provides its fertility. It is the soil biology that makes the minerals and (added)
chemicals in the soil available to the plant.
What is the Soil Food Web?
The soil food web is based around the tonnes of beneficial bacteria, fungi, protozoa and nematodes
that live in soil or compost. The plants we see above the ground are in a complex symbiotic
relationship with microbes in the root zone. It is soil life that provides the “living bridge”
to store and make nutrients in the soil available to plants.
There are four main categories of organisms that make up the soil food web:
Bacteria
Fungus
Protozoa
Nematodes
Bacteria
Bacteria are the most numerous microbes in the soil with populations ranging from 100 million to 3 billion in a single gram of soil/compost.
Assist in organic matter decomposition.
Are responsible for components of nutrient cycling and retention (especially N).
Help build soil structure.
Help with disease suppression.
Help to decompose toxins in the soil.
Fungi
Soil fungi assist with the “hunting and gathering” of nutrients. Mycorrizal fungi are a key component to soil and plant health.
Assist with enzymatic breakdown of cellulose, lignin, wood, hair (C).
Decompose toxins.
Release, recycle, store and transport nutrients. (makes Ca, P and trace minerals available)
Helps suppress and compete with plant pathogens
Hyphae (rope-like tubed structure of the fungi) tie soil together to give structure. Fungal glues (glomalin) stick it all together.
Mycorrizal Fungi
A type of fungi that attaches itself to the root of the plant. It has a very special symbiotic relationship with the plant root. By entwining itself around the root, it provides for better protection of the root from predatory bacteria, fungi, and nematodes.
Symbiotic function with the roots of the plant.
Hyphae of the Mycorrizal fungi grab the nutrients that are unavailable to the plant and make them available via the enzymes in the fungi.
Also does this with water for the plant.
Mycorrizal fungi builds walls around roots, protecting infection sites and producing antibodies.
The plant gives the fungi food in return. (simple sugars, proteins, carbohydrates).
They are present in most growing situations.
Protozoa
The protozoa group is made up of flagellates, amoebae, and ciliates. Excess numbers of ciliates indicate an anaerobic state in the soil.
Feed on bacteria, making nutrients immediately plant available.
Responsible for 40% of the net mineralization.
When bacteria, with a C: N of 5, get eaten by a protozoan with a C: N of 30. N will be released in a plant available form.
Nematodes
Nematodes are the “living store house of nutrients”. There are 5 main groups of nematodes: bacteria feeders, fungal feeders, fungal/roots feeders, roots feeders, and predators.
Beneficial nematodes eat and digest bacteria, fungi and protozoa making nutrients available to plants.
Building soil structure – make tunnels, creating aerobic conditions in the soil.
Some nematodes eat and digest the meat of the root-feeding nematodes.
Fungi to Bacterial Ratios
There is a balance between Bacteria and Fungi depend on the crops to be grown. (This ratio is based on weight of the organisms, not numbers.)
Weeds - F:B - 1:10
Early Grasses F:B - 3:10
Mid-grasses, vegetables F:B - 3:4
Late grasses, row crops F:B - 1:1
Shrub, vines, bushes F:B – 2:1 – 5:1
Coniferous, old growth forests F:B – 100: 1 – 1000:1
Food Web Disturbances
(practices that hinder or harm the biology of the soil)
Clear cutting, thinning
Compaction
Fertilizers, pesticides, herbicides
Temperatures
Moisture
Deep or repetitive tillage
Cropping practices
Organic Matter (timing, type, placement)
Air Pollutants
A Soil Biology test will give you information you need to determine what your soil biology is and
if your fungal to bacteria ratios are in balance for your desired crop.
For more information, go to www.soilfoodweb.ca.
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