Home | Business News | Browse by Publication | M | Mushroom News

What is compost quality?

Article Excerpt
Many scientists and growers have described their thoughts on mushroom composting through the years. We will describe our understanding of what goes into quality compost and how one may go about assessing the important details during Phase I and Phase II composting. We will also touch on what the mushroom uses for food and end with some cropping research conducted at Penn State.

[ILLUSTRATION OMITTED]

The objectives for Phase I and Phase II composting are to: 1) soften rigid plant materials; 2) increase the water holding capacity of the raw materials; 3) form complex carbohydrates to preserve carbon for the mushroom; 4) generate and subsequently convert ammonia to microbial protein; 5) create substrate with sufficient nutrients to grow a good crop of mushrooms while providing little or no nutrition for other fungi and competitor organisms. By accomplishing the above goals you will develop a substrate with adequate nutrients to insure rapid, healthy mushroom growth and yields, and at the same time provide little to no nutrients for other potential competitor organisms.

[ILLUSTRATION OMITTED]

Growers need to assure that these goals are being accomplished during and at the completion of the composting process. Describing and measuring compost characteristics is one way to maintain a successful composting process. This process involves sensory perception as well as chemical and physical assessment throughout the composting procedures. Sensory assessment includes touching, seeing and smelling the compost. The chemical assessment includes a laboratory analysis for pH, percent nitrogen, moisture, ash and ammonia. Presently, physical analysis of mushroom compost is confined to the research laboratories. However, with the development of a new technology for Municipal Waste Composting systems, commercial application of these analyses is becoming available to the grower. Thermal and spectroscopic analysis of compost may someday soon be as common as the nitrogen, ammonia and ash analysis you use now.

Is composting different with an aerated Phase I system? Dr. James Sinden once wrote "With complete aeration, composting will proceed more rapidly" and he continued with "the practical composting process should be limited to the minimum time necessary to produce a favorable substrate. Composting beyond that minimum merely destroys organic material usable by the mushroom without serving a purpose. Growers should make small tests to see whether they are composting longer than is necessary. By maintaining the minimum composting time, a grower should recover a maximum return per unit of ingredients purchased." That was written over 50 years ago, and accurately describes Forced Aerated Composting, a concept that was not brought to commercial fruition in the United States until the 1990s. His other comments remain accurate and provide good advice in these days when the cost of compost ingredients continues to rise.

[FIGURE 1 OMITTED]

So what sensory assessments can growers use to assess mushroom compost? The most common is visual. Growers are often looking at the color of the compost to determine the maturity level at certain times during the Phase I process and prior to filling. The degree of compost maturity and breakdown may differ from farm to farm depending on the system used for Phase II. It is often more desirable to have more mature and denser compost in a bed system in order to achieve high dry weights needed for higher yields. However, less mature compost has a greater water holding capacity at spawning time and later, which is one advantage of a bulk system where longer, less mature compost seems more desirable. The yellow-green color of the compost also may indicate whether the compost was anaerobic at some time. In anaerobic compost, organic acids are formed that are detrimental to mushroom yield or microbial activity, and will encourage the growth of Trichoderma Green Mold disease.

Another visual observation includes accessing the steam coming out of the pre-wet piles, indicating microbial activity has started. Since the compost ingredients harbor many naturally occurring microbes, wetting and mixing ingredients provides the necessary microbial growth and reproduction requirements. Steam is...

View this article FREE - Now for a Limited Time, try Goliath Business News
Free for 3 Days!