How to grow mushrooms

How to grow mushrooms

Looking to start growing mushrooms? This mushroom farming series - with all the mushroom advice on how to start growing mushrooms, could be... 5:52:00 AM

Looking to start growing mushrooms? This mushroom farming series - with all the mushroom advice on how to start growing mushrooms, could be for you.

In Zimbabwe, people usually eat wild mushrooms during the rainy season so consuming commercial mushrooms is kind of a new thing – which does not mean there is no market for it. Good advice will be that you do your research first as there is no readily available data on the sector.

What you need to know about growing mushrooms

Most mushroom supplies comes from commercial mushroom farms since growing mushrooms is necessarily a simple operation – but with determination, knowledge and the right tools, anyone – even in the rural areas, can have a mushroom growing operation going.

In the developed countries, mushroom growing is a technology-based and sophisticated agricultural activity, which drives commercial mushroom production costs high – but we are in Africa, we make plans!

As said before, what is needed - whether you are growing your mushrooms on a large/small scale with modern mushroom production equipment or in your backyard with rudimentary materials, is knowledge, a high level of management skill, commitment to success from cropping, to marketing.

You should also know that mushrooms have a bad reputation for wiping out whole families so you want to be very knowledgeable about the kind of mushrooms that you plan to grow.

White button and brown mushrooms are mainly popular on most supermarket shelves as well a few exotic mushrooms fill up a small space of the market. For some reason, most mushrooms go to the fresh market and a small percentage are processed into canned product, sauces and other value added products.

The basic process of growing mushrooms is set out below.

1.    COMPOST

Mushrooms are basically fungi and lack chlorophyll to produce their own food hence they feed off organic material. So, you need a good compost or if funds permit - a highly complex substrate.

A well-prepared compost for mushrooms is the result of a somewhat complex, controlled biological process involving micro-organisms. A high yielding compost is probably the most difficult part of growing mushrooms.

Here are the ingredients for a mushroom compost:

1. Water – this is essential for the composting process and eventually for growth of the mushroom; on average 70-90% of all the mushroom’s water requirements is extracted from the compost
2. Straw (mostly wheat) - supplies the carbohydrates and provide the correct structure to allow aerobic conditions
3. Broiler chicken litter - acts as a nitrogen source and supplies microbes needed for the composting process to take place
4. Gypsum - added to improve the structure, buffers the pH and aids the release of ammonia

The quantities used depends on the chemical analysis of the nitrogen content of the chicken litter.

A typical formula is: 1 000kg straw (moisture content 15%); 800kg broiler chicken litter (moisture content 40%, nitrogen 4%); 85kg gypsum.

Preparation:
 

Prewet

The purpose of this phase is to wet and mix the raw materials - biological activity does not take place unless water and a supply of available nutrients is added. Straw bales are stacked outside and continuously sprayed with water (often the run-off water from the compost yard collected and aerated in a pit).

After wetting for 5-6 days the bales are broken and part of the chicken litter (30-50%) is mixed through. The portion of chicken litter applied depends on the quality of the straw, the time of the year (in summer less is added in the beginning) and the nitrogen content of the chicken litter.

The initial wetting and mixing phase occurs over a period of 7 days.

– Rick Method

After wetting and mixing the compost is formed into long narrow stacks or windrows (typically 1.8 - 2m wide and 2m high) either in the open or in a covered area. The stacks are mechanically turned with compost turners (usually every other day) and watered.

At some point the balance of the chicken manure is added and mixed through. This process allows for micro-organisms to grow and reproduce. Their activities cause the temperature in the pile to rise. The centre of the stack should reach 70 - 80oC. Much of the nitrogen present is ammonified. 

Such a conventional phase I usually takes about 7 days.

– Bunker Method

Over the last few years, the use of specially built bunkers with under floor ventilation and sometimes with an open or partly open top has become popular. This is to make the process more environmentally friendly by reducing the “smell pollution” dramatically. After the initial pre-wetting and mixing of the raw ingredients (5-6 days) the material is built into a loose flat pile and turned every other day for approximately another 7-10 days.

At some point the balance of the chicken manure is added and mixed through. Temperatures in the pile are kept from exceeding 65oC in order to allow microbial activity. From there the material is filled into a bunker. Oxygen levels in the bunker are monitored to ensure that compost does not go anaerobic. The supply of air from below the pile results in the bulk of the compost reaching temperatures of more than 80oC.

The wetted and mixed ingredients are usually taken out of these bunkers at 3-4 day intervals and put back (total of about 7 days). The move during this process ensures thorough mixing of the ingredients.

At these high temperatures microbial activity ceases and chemical reactions take place leaving the compost with a dark-brown colour indicating caramelization and browning reactions have occurred. At this stage the compost should be pliable, the water content 72-75%, the smell of ammonia very strong and the pH in excess of 8.

2.    Phase II (peak heating/pasteurization)

Phase II is carried out under carefully controlled conditions mostly in bulk in specific designed tunnels with aerated floors. Phase II has two main purposes, firstly pasteurization (to free the compost from undesirable microbes and pests) and secondly conditioning (to become mushroom specific by getting clear of ammonia and free of readily available carbohydrates).

Through proper manipulation of temperature and ventilation these two primary objectives are accomplished. Initially the compost is allowed to settle so that it is more or less uniform throughout. This may take up to 10 hours and is called equalizing or levelling.

Thereafter the pasteurization (also referred to as the kill) phase occurs where the temperature is allowed to rise to 60oC (either by itself or by the introduction of steam). The temperature is held at this level for 8-10 hours. 

After pasteurization the temperature of the compost is reduced to 48oC for the conditioning process which usually is about 4 days. In total the phase II process usually lasts about 6 days. At the end of conditioning the compost must be stable and free from ammonia. It is then cooled to around 25oC by circulating filtered air through the material.

At this stage the compost should have a moisture content of 68-72%, nitrogen content of 2.3-2.4% and pH of around 7.3 and ready to be spawned.

See next post for the other steps.