Biuletyn producenta Pieczarek PIECZARKI 4/2017 S. 32-36
Could supplements make standardisation of substrate possible?
dr Nikodem Sakson, Poznań
Changing quality of substrate is a fact. There are many reasons for this. One of them is that methods of controlling the process of compost production are not precise enough. You can find my propositions of changing this status quo in the last issue of Bulletin. Nevertheless solving the problem of producing substrate of stable quality can be resolved by actions taken in compost yards. Lack of changes in the quality of compost is the reason of searching for solutions allowing for standardisation of substrate on mushroom farms. One of these solutions could be usage of new generation substrate supplements that are based on high content of easily available cellulose and hemicellulose. They are called cellulose supplements for substrate.
Mushrooms intake of nutrients from compost takes place in two forms. The first is by dead microorganism that is in compost after its maturity phase, the other is left over degraded straw and supplements.
To improve the quality of substrate different supplements are used. They can be divided into two basic groups:
- Compost supplements. Their role is to maintain desirable ratio of carbon to nitrogen and to maintain availability of carbohydrates and nitrogen during composting process. For further information on this topic read my article in Bulletin no. 3/17;
- Substrate supplements, for differentiation called ‘feeding supplements’. Feeding supplements used nowadays do not allow for full standardisation of substrate. The reason for this is that when deficiency of nutrients is high enough, maximum dosages of feeding supplements cannot reduce it. Those limitations are the result of the way feeding supplements influence thermal effects. Limited, in given time, high assimilation of nutrients that the feeding supplements are containing is also the reason. A new formula of supplements is based on ideas taken from complete feed for animals. It means that the content and availability of nutrients can allow for mycelium to feed on them the same way as on compost. Hence the feeding supplements have to meet the following criteria:
- They have to absorb water (fully moisturize itself) during few hours since introduction to substrate.
- The transfer of nutrients from feeding supplement to mycelium should be 50% of their content during 72 hours.
The ratio of nutrients and their treatment is based on scientific researches that are the basis of modern biotechnology. Raw materials from grass fulfil these criteria. They undergo the processes that allow for their easier availability (as in compost).
What goals can be achieved when using feeding supplements that are rich in cellulose?
- Reaching projected volume of yield, independently of the quality of substrate. The dosage can be as high as several or even over a dozen per cent of substrate’s weight. What is expected is the increase in yield of the second and third flushes with maintaining of high volume weight of fruiting bodies in all flushes and maintaining of previous spread in consequential flushes.
- Elimination of thermal effect after placing on the shelf and during the growth, mainly between the first and the second flushes. In case of low activity, starch supplements could be introduced.
- Elimination of threats as green mould in the third flush by using feeding supplements to casing soil, that would be fully assimilated by mycelium until the end of shock and are not colonised by green mould after lowering of pH in casing soil during the third flush.
Cellulose supplements introduced to substrate are used by Agaricus as a source of glucose in the process of external enzymatic degradation. This process is most effective in temperatures of 23-270 C, so in temperatures in which the growth of mycelium is the quickest. Exceeding temperature of 300 C stops the process nearly completely. Controlling the temperature may be easier because of high water capacity of these supplements. As a result thermal effect is eliminated. This effect was the main reason of reduction of possibilities of using high dosages of available nowadays supplements with high protein content. They are the cause of increase of temperatures, which obstructs usage of cellulose and hemicellulose it is containing. Usage of which decreases when the temperature of substrate is higher than 270 C. Initial increase of substrate’s temperature after being placed on the shelf can be fully controlled by using higher dosages of water. Higher water capacity of substrate that is enriched that way makes controlling the temperature easier. The beginning of increase of temperature signifies the moment of starting of assimilation of glucose from feeding supplement introduced into substrate.
Additional factor that can stabilise the yield is usage of the feeding supplement in the casing soil. The requirements are similar as to using feeding supplements in the substrate. Recommendations which are to be followed to effectively use supplement to Nutrigain casing soil can be an example of this. After introduction to the casing soil with the last two litres of water, it is to be covered by micro perforated foil. The air flow should be reduced, so the temperature of casing soil is high enough. Covering it allows high concentration of carbon dioxide to occur, which benefits enzymatic activity of the mycelium.
Goals of using cellulose feeding supplements that were mentioned above are to be reached without the raise of cost (or in very small increase), because raw materials used in their productions are cheaper, and also the cultivation process can be done on a smaller amount of substrate.
If the compost producer doesn’t provide services of putting the feeding supplement into the compost projected goals can be achieved by self-determination of the dose of feeding supplement and putting it into the substrate in a mushroom farm during placement of the shelves. In smaller companies the dosages could be established based on the individual check of the quality of compost and will take into consideration using excessive amount of feeding supplements over the projected yield volume. Bigger mushrooms farms can establish the dosages and recipes based on the actual needs, using mobile NIR spectrometer that allows checking substrate’s quality during loading.
Is this solution a real one?
Using cellulose supplements seems to be a real solution of problems with standardisation of quality of substrate, but is it really? And to what extent? Also can it be implemented in all kinds of substrates that are produced in Poland? To answer those questions several tests in production context have to be conducted. Results of first tests show, that there is a high probability of achieving this goal.
One can assume this solution has potential for real changes, because it is based on solid scientific knowledge.
For mushrooms the straw in compost is the basic source of glucose, assimilated from cellulose and hemicellulose in it. Their placement is the problem. They are in cell walls surrounded by lignin, which is not digested effectively by Agaricus’ enzymes (in contrast to Pleurotus, which has this ability and so can be grown on straw itself). For mushrooms to have access to glucose straw has to be submitted to the process of composting or to be mechanically teared. It is shown on illustration number 1.
Raw materials used in production of feeding supplements are usually wastes occurring during agricultural production or are cheaper than wheat seeds or soya. But they need additional processing: grinding and tearing of cell membranes (extrusion, expanding or micronization). The process of tearing the membranes allows for sanitization of supplement (getting rid of potentially harmful microflora), at the same time those processes have to be done properly, as not to allow for substances that limit mycelium’s activity to occur.
Processing of raw materials causes significant increase in feed supplement’s water volume and easier humidity and as a result, increases in assimilation of nutrients that are in it. Giving mushrooms source of nitrogen, which is obtained by enzymatic decomposition of proteins, is significant too. Cellulose feeding supplements have got some amount of proteins and other components essential for mushroom’s life. Those contents are located in dead cytoplasm of cells of plants used as raw material for their production. There are also micro- and macro elements essential for mushrooms life in feeding supplements, but in case of lack of them they can be supplemented using TOP Vital. Its composition can be matched according to current needs.
Achieving positive results during conducted test will depend on development of technology of using high dosages of cellulose feeding supplements. On one hand the development should influence placing and correct mixing with substrate, on the other hand – balancing the dosages of water.
Other tests are also conducted on dividing the dosages of feeding supplement, when it is put in a part of phase II substrate. However using this solution is limited because of the humidity of the compost. Dosages that are too high may lead to deficit of water, at the same time limiting its usefulness. Feeding supplement implementing goals, that were mentioned above is produces by company Aril. (Photo 1 and 2)
Developing technology, which would allow increase in high quality yield and reduction of production costs, are significant factors in maintaining competitiveness of mushrooms produced in Poland.
Photo. 1. New product
Photo. 2. Previous product
Illustration. 1 Processed lignin-cellulose fibre
Source: based on: L. Kratky, T. Jirout, Biomass size reduction machines for enhancing biogas
production, „Chemical Engineering&Technology” 2011 no. 34, p. 391-399. Cited in: Kamil Witaszek, Agnieszka Anna Pilarska, Krzysztof Pilarski, Wybrane metody wstępnej obróbki surowców roślinnych stosowanych do produkcji biogazu, „Ekonomia i Środowisko” 2 (53), 2015, p.130-144