Maturity cannot be described by a single property. Some laboratories assign a maturity index to compost based upon germination rate, root tissue growth, and other factors. The California Compost Quality Council (CCQC) developed a numerical Maturity Index that uses standard laboratory tests to rate compost maturity. To qualify as “mature” or “very mature,” a compost must have a C:N ratio of less than or equal to 25 and pass two additional tests performed concurrently from each group:

• Group A tests, which indirectly measure the degree of organic matter decomposition, include carbon dioxide release or respiration; oxygen demand; and Dewar self-heating test.
• Group B tests, which measure chemical characteristics of the product (some of which can be toxic to plants) include ammonium nitrate ratio; ammonia concentration; volatile organic acids concentration; and plant bioassays.

www.CCQC.org publications describe how to apply the index and interpret test results to determine whether a compost is very mature, mature, or immature, and provide general guidelines on best uses of composts based on the Maturity Index rating.

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Jugalbandi wrote an excellent post about soil and organic matter on their blog.  They talk about the importance of soil organisms, taking care of organic matter and more.  They also recently received a bottle of Great Big Plants and wrote some of their thoughts on it as well.  Take a look at their blog to get into the nitty gritty on dirt.

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There are several million to billions of organisms, which typically require a microscope to see, that live in soil and around the roots of plants. The way these organisms interact with each other and with plants is called the Soil Food Web. There is a best balance of all the different kinds of microorganisms for each kind of plant to get best plant health and quite often improve yield. A spoonful of healthy soil should contain only beneficial species of bacteria, fungi, nematodes and protozoa that never cause disease or become pests. These species perform vital “functions” in the root zone that can bring real profits to growers IF soil conditions are managed in ways that allow the microbes to live and work.

Think about the dollar potential involved with each of the following six functions and then be aware that these functions are entirely biological and only occur through a soil foodweb that is built up, intact and working!

A balanced Soil Food Web will:

1. Suppress disease-causing and pest organisms
2. Retain nitrogen and other nutrients such as calcium, iron, potassium, phosphorus, etc.
3. Make nutrients available for plant growth at the times plants require at the rates plants require.
4. Decompose plant residues rapidly.
5. Produce hormones that help plants grow.
6. Produce good soil structure, improving water infiltration, oxygen diffusion, and water-holding capacity.
7. Consume pollutants in the soil.

Products and cultural practices that stimulate a “bloom” of bacteria or fungi reproductive growth can be used as tools to achieve nutrient retention. When this function is working in your soil, half of the process that leads to lower rates of N and P with no reduction in crop yield is present. You are retaining N, P, S, Ca, K, Fe, etc, in your soil, and they will NOT end up in surfGreat Big Plants-Soil Imunity Booster or groundwater any longer. Recent studies at SFI have shown that fungi are the most important retainers of calcium in the soil. Lose your fungi, and you lose the ability to retain Ca in the soil.

More information on this will be coming soon so stay tuned to this page!

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