Designing a Small-Scale Organic Agaricus Mushroom Production System to Provide Additional Income to Family Farms

Final Report for FNC06-614

Project Type: Farmer/Rancher
Funds awarded in 2006: $6,000.00
Projected End Date: 12/31/2008
Region: North Central
State: Missouri
Project Coordinator:
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Project Information


We are a small family farm, with two and one half acres located in Ozark county Missouri. Most of our income comes from the production of mushrooms. We supplement it with garden vegetables and work obtained outside of the farm. We use no chemicals on our garden produce and use only neem oil and pyrethrum for control of fungus gnats in our mushroom crops only when needed. The majority of our products went to grocery and restaurant outlets. The remainder was sold at farmers markets. We produced around 1,000 pounds per week. This has changed since the beginning of the project. We now sell to mostly natural food stores, CSAs and farmers markets and produce approximately 200 pounds per week.

We have always tried to keep our growing practices as natural as possible -- buying local ingredients whenever possible and distributing our products close to home.


GOAL: Our objective was to provide an income means for farmers who wish to increase their farming incomes through limited resources available to them locally.

PROCESS: The first part of our process was to determine the size of our project. We had to ask ourselves many questions.
• How many hours can someone dedicate to this process? So we decided to keep the hours at 20-25.
• What types of equipment will they have available? Most farms have tractors or other machinery capable of composting but we decided to design around an all manual labor design – keeping it small enough to accomplish a reasonable production without the use of machinery. This gave us limits to crop sizes and tray dimensions.
• What types of materials will we compost with and how far will we go to get them? This was a hard question. Since I started this project prices have soared. We tried to buy as close as possible using many types of hay and straw. Our best choice was wheat straw grown within 30 miles at a cost of $3 for a small square (40 pounds). This material was weedy but worked. We also utilized manure from our own animals. Horse, chicken and rabbit manure from our farm was used along with distillers’ grain, cottonseed meal and gypsum from feed stores.
• The next question was tray size? The tray had to be big enough to hold some mass while being able to be handled by hand. We decided on 32 by 36 inches, made with 2 by 8 material with 5/4 deck boards on the bottom with 4 inch blocks attached to the bottom corners. This gave us a growing area of 7.25 sq ft per tray and could be stacked by two people. Also, this size of tray fit very snugly into a room we used as our phase II room.

So with some beginning questions answered it was time to start jumping hurdles. We started off by composting many types of materials. The results were variable. I am not saying that it is not possible, just more difficult. Also, at the beginning we were composting for enough compost to fill just 12 trays per week. Crops this small proved hard to manage in respect to temperature and overall biomass. So our solution was to compost two weeks material at a time. Then these crops would be cased on day 10 and day 17 after spawning.

Here is a formula that seemed to work most consistently for us.

30 Bales wheat straw
150 pounds of distillers’ grain
100 pounds of cottonseed meal
100 pounds of gypsum
50-75 pounds of available manure from around the farm

This formula gives us a cold-start nitrogen of approximately 2 percent. This is fairly typical for mushroom production.

Our procedure for composting was done on a covered concrete slab and is as follows.
• Day 0-7: We stacked bales into two layers (16 bales bottom layer and 14 counter stacked on top layer). Placed a typical black soaker hose on bales and soaked for 2-3 hours every other day. This pre-wetting the bales helped break down the waxy coating and helped the straw start to heat.
• Day 8: Broke bales open and loosened straw. Sprayed with water while doing this (water should be able to squeeze through fingers fairly easily – 72-75 percent moisture) then added any available litter and 100 pounds of distillers. Thoroughly mixed these materials together and placed in a bunker or stacked into a bread loaf shape. We used bunkers approximately 7 feet high by 6 feet wide. (A bunker is a bin used to stack compost in. We used two bunkers. One 6 feet wide by 10 feet long the other 12 feet wide and 10 feet long.)
• Day 11: Flipped and mixed compost adding water as needed. Keeping moisture at 72-75 percent
• Day 13: Added 50 pounds distillers flipped and watered as needed.
• Day 16, 18, 20: Flipped and mixed, adding water as needed.
• Day 22: Added 100 pounds of cottonseed meal and 100 pounds gypsum. Mixed thoroughly and added water as needed.
• Day 24, 26, 28: Flipped and mixed, adding water as needed.
• We wanted to obtain 72-75 percent moisture. A simple test is to wad the material up in your hand and squeeze hard. The water should come through ones fingers fairly easy. When getting closer to fill we backed off on the amount of water added. As we composted we were growing bacteria, which used the ingredients added as food. As we grew bacteria, our compost heated and respired water and CO2. In return we got a nitrogen rich hummus complex. (This is an aerobic process and if the compost gets too wet, it would stop composting and promote the growth of anaerobic bacteria. If the pile is orange at the bottom core the pile is too wet and is lacking oxygen.) Temperatures from day 10 through fill were above 140 degrees and reached 160-170 degrees. Composting for mushroom growing is a trial and error process and takes time to master.
• Day 30: Trays were filled and placed into the phase II room. The phase II is very well insulated and large enough to just fit our trays. We built ours with a small fan to re-circulate the air and a damper to allow in fresh air to control the temperature. Some extra heat may be needed depending on the time of year. In this room we did the final conditioning, pasteurized and cleared remaining ammonia from the compost. After fill, compost temperatures usually fall and needed to be brought back up to 130 degrees and held there for 48 to 72 hours by adjusting the air temperature in the room with fresh air. On day two or three we would close all dampers and allow air temperature to reach 136-140 degrees. This took 4 to 8 hours depending on the activity of the crop. Our bed temperature would go above 140 degrees. This killed any fly larvae and nematodes that did not die in composting. After pasteurization we would bring the temperature down slowly over the next 48 hours holding it at 118-125 degrees. These are optimal temperatures for growing actinomycetes bacteria. These thermophilic bacteria cleared the remaining ammonia from the compost. Once there was no smell of ammonia we would cool the compost down to 85 degrees by opening dampers.

Now it is time to spawn. We removed the trays from the phase II and unstacked them. Usually we sprayed a little bit of water on the dry surface. We added spawn to the surface and thoroughly mixdc throughout the tray using pitch forks. The compost was then pressed back into the tray and covered with a thin plastic, stacked and taken to the growing room. Our growing rooms are 7 by 20 feet and are equipped with a small fan to blow air in from our air conditioned hallway. After spawning the trays were split between two rooms. During spawn run we kept the compost temperature at 76-80 degrees with an air temperature of 68-72 degrees. For the spawn to completely colonize the compost we needed at least 10 days. If the compost was not optimal it took longer. The spawn we used was a sterilized rye grain with the strain of mycelium grown through it. We inoculated our compost with the spawn. We purchased the spawn through a spawn maker.

On day 10 after spawning it was time to case. We added spacer blocks of 10 inches between the trays for easy access. Casing is the addition of a peat, lime and water [mix] to the surface of the colonized compost. We cased 12 trays at a time and usually used 6 cu. ft. of peat and 100 pounds of lime. We dry mixed these ingredients then added water. We wanted the moisture at 80 percent in the peat layer.

We mixed these ingredients on the floor with a shovel. After it was wet we added some well-colonized compost to the mix, which shortened our pre-flush time. Then we filled the peat-lime mixture into tubs and evenly distributed over trays. Our casing was about 11/2 inch to 13/4 incih thick. After it was spread evenly I pressed it to firm it up and make the density more consistent then I lightly scratched the surface.

After casing the crop was in casehold period. During this time the mycelium colonized the casing layer, we flushed the crop and set pins. Maintaining water in the casing is important and would take light waterings every day or every other day. Very lightly applied water was used to avoid sealing the surface. Bed temperature was maintained at 80-82 degrees with air at 70-72 degrees.

We kept dampers closed and recirculated the room air. This raised the CO2 in the room and helped keep the mycelium from pinning as it reached the surface. On day 4-6 we would see a fair amount of growth in the layer and it would pop through the surface. Once we saw about 50 percent of the tray with mycelium on it, it was time to flush. When we flushed we were basically removing all the stale air from the room and replacing it with fresh air. We would drop the CO2 and air temperature, shocking the mycelium sending it from a vegetative state to a reproductive state. [This involved] opening dampers to allow in fresh air and maintaining air temperature at 62-65 degrees. We watered every other day until pins were the size of an eraser. Usually we would see mushrooms 18-20 days after casing.

Picking is another art form in the mushroom growing process. We would pick our buttons just before they started to open and allowed the portabella to open fully. This is truly a trial and error process. Each picking is referred to as a break, usually getting 3-4 breaks per crop over a 3-4 week period. Once the mushrooms are completely picked off we watered the beds again and in 5-8 days we would get another break.

After we have picked the final mushrooms from the crop it is time to dump. The compost is removed from the trays, the trays are cleaned and the process starts all over again. One cannot use the same compost again it is spent as far as growing mushrooms is concerned.

We mix our mushroom compost with worm castings and kelp and sell it buy the bag. This is a great soil amendment.

Every two weeks we start a new crop and repeat the process as outlined above.

• Bob Semyck- Personally involved to see that all aspect of the operation were carried out.
• Wendy Semyck (wife)- Assisted with all operations, data acquisition and website.
• Robert Semyck (son)- Assisted with filling, spawning, casing, dumping and packing.

Results in mushroom growing are usually measured in pounds per square foot. A rule of thumb is for every pound of dry matter spawned you should get a pound of mushrooms. This is measured as bio-efficiency. If you spawn 7 pounds dry weight per square foot you should get back 7 pounds of mushrooms at 100 percent efficiency. Well our little venture does not include the machinery or computer controls that large factory farms have. But on the other hand our farm does not have all the corporate cost that a large farm has. So our bio-efficiency may be a lot less but we make up for it in less cost and a higher price per pound.

Our first set of trials performed very poorly. Low dry weight and poor phase II caused problems for the rest of the growing process.

Our second set of trials performed much better. We did not have a way to get exact dry weight per square foot but figured it to be around 4 pounds per sq ft. We usually got about a 50-75percent bio-efficiency; higher on the white buttons, lower on the portabella.

Every week we would case 6 trays white button and 6 trays of portabella. Each tray is 7.25 sq ft giving us 43.5 sq ft of each cased every week. Our yield on the buttons was 3 pounds per sq ft and on the portabella was 2 pounds per sq ft.

White Button = 43.5x3=130.5 Portabella=43.5x2=87

Our average price on buttons was $3 per pound = $392. Our average price on portabella was $6.5 per pound = $566 for a total of $958 gross/week. Our cost, which includes utilities, transportation, packaging and raw materials was around $300 weekly, netting a weekly income of $650.

Though we have had some success with designing a small-scale system that works. I would like to work with someone with no mushroom growing experience. This would help in writing a manual or step-by-step procedure.

We have become better marketers of our products, going to fewer customers at a higher price per pound. We have been able to proportion our time better to the amount of work we do to the number of hours there are in a day. As distribution costs continue to rise, our small family farm will be more competitive with larger farms. I see a good future for the farmer who wants to be hands-on and go directly to the consumer. I feel that any small community of 10,000 to 20,000 could support a small mushroom farmer and his family.

• We gave two talks at Baker Creek Seed in Mansfield, MO for the Ozarks Regional Foundation of Hartville, MO. 7/6/09 we had 10 attending and10/4/09 we had 20.
• We also shared this information with our customers at farmers markets.
• We also have a link to SARE on our website.
• We give tours of our farm to those who are interested.


Participation Summary
Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.