Sáhara Occidental

B.Vijay

The nutrient sources are added to compost at the time of its preparation for balancing the C: N ratio and to start the fermentation process. The microorganisms developed during the course of composting phase utilize these nutrients resulting in formation of nitrogen rich lignin humus complex. This along with decomposed straw is later utilized by the mushroom mycelium for its growth. Here we are talking of a nutrient, which is first, attacked by microorganisms and later by mushroom mycelium. These nutrients can be designated as pre-composting supplements. However, there is another class of nutrients, which are added at any time after completion of composting for direct utilization by the mushroom mycelium. These are generally referred as post composting supplements.

It has become a routine practice to supplement the compost at spawning and at casing (post composting supplements) in advanced countries as this encourages stronger and healthier growth of mycelium, which results in higher yield. There proprietary products of protein or carbohydrate origin are readily available in the market, which guarantee the increased production to the tune of 20% or more. In India, since the mushroom cultivation is still not very well developed and organized, many farmers have not adopted this practice. Lots of work has been done in the country on this aspect and it has been proved beyond doubt that supplementation increases the yield of A.bisporus and this practice can become integral part of button mushroom cultivation.

Supplementation can be tried both with compost prepared by long method or by short method compost. Number of considerations are to be kept in mind for raising a successful crop through supplementation of the compost, like choice of supplement, type of compost used, mode of application and rate of supplementation, etc.

A. Choice of Supplement

Supplements used in the mushroom cultivation can be of both animal and plant origin which may be carbohydrate-rich, protein-rich or oil-rich substances. However, protein-rich materials give better results. In India, cotton seed meal, soybean meal, cottonseed cake, deoiled soybean meal have been tried with fair amount of success.

Besides these, yeast extract, ammonium sulphate and vitamin B complex have also been used as supplementing agents with fair amount of success. Other supplements tried/worth trying include alfalfa meal, lucerne meal, corn gluten meal, cracked soybean, groundnut cake and sunflower meal. Supplements from animal origin include feather meal, bone meal, etc., which have not been tried in India so far.

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B. Compost Formulations and Type of Compost Used

Initial compost formulations and type of compost produced affect the response to subsequent supplementation. It has been observed that supplementation with the same substances may not increase the yield in different compost. It has further been observed that too wet or too dry compost which does not support better growth of mycelium may not prove fruitful for supplementation. Better response to supplementation is always achieved when one starts with the formula in which required ingredients are added. However, a meager compost having no nitrogen may respond positively to supplementation. This increase may be due to the make up of already lacking nitrogen status. As already stated, supplementation can be tried both with the compost prepared by long method and short method. It has, however, been found that sometimes long method compost may behave erratically with the supplements giving little increase/no increase or lesser yields.

The length of composting period also determines response to supplements in these composts. In general, it has been observed that long method compost prepared over a time of 28 days in which dry matter loss was more responded more favourably to supplements than the composts which were prepared in 20 and 16 days.

C. Mode of Application

First requirement in this case would be to coarsely grind the supplements. The supplements like soybean or cottonseed meal may carry different weed moulds and are to be eliminated before their application in the compost. Formalin (40% formaldehyde) is generally used for this purpose, which serves the dual role. It sterilizes the supplement and at the same time, partially denatures the proteins present in the supplements. 5000 ppm (0.5%) formaldehyde treatment of cottonseed and soybean meal is sufficient.

Required quantity of supplement is taken in a clean container for its treatment and formalin dissolved in water is poured over the supplement. One kg of supplement would require around 1.0 ml of commercial formalin dissolved in 700 ml of water. This solution is properly mixed in the supplement and dough is made. Later the container is sealed with a polythene cover and left as such for 48 hours to facilitate the proper action of the chemical.

D. Rate of Supplementation

Rate of application of supplement in compost varies from 1-6%. Rate of a particular supplement is determined by its ability to mix properly in the compost and also the temperature control facilities available with the grower. Moisture content of the compost, compost depth and its density is also taken into consideration. Best results are however obtained when supplementation is practiced in perfect compost. If all these factors can be manipulated, supplements can be used at as high as 5-6% to get dramatic yield increase. If supplementation has to be done in the compost kept in shelves than its addition @ 1.5 kg/m² gives best results. When tried in bags then best results are obtained with one percent supplement on wet weight of compost. Higher doses of supplements than the recommended doses can be counterproductive.

E. Time of Supplementation

Breakdown and utilization of nutrients of supplements by mushroom mycelium and other organisms present in compost result in heating up of the compost. Sometimes

99 Post Composting Supplementation

heat generated is so high that mycelium may be killed. Care, therefore, must be taken about the time and rate of application. Mostly supplements are added in the compost at spawning or at casing. Better results are however obtained when supplements are added in the fully colonized compost at casing.

F. Supplementation at Spawning (SAS)

In this case, pretreated supplement mentioned as above is mixed in the compost alongwith spawn and filled in the bags or trays or shelves. In India, supplementation at this stage has been tried both with unpasteurized (LMC) and pasteurized compost (SMC).

Growers who are not having cooling facilities at their farm should not resort to this practice at this stage as temperature tends to increase in the compost due to supplementation (3-4⁰C rise) which may sometime exceed too high resulting in death of mycelium or high temperature may generate secondary metabolites including ammonia lethal to mushroom mycelium. Selectivity of the compost may also decrease when supplementation is tried at this stage, which increases the risk of weed moulds incidence.

Sometimes the supplements stick to the spawn, which in turn, contaminate the compost (personal observation). It is, therefore, suggested that while trying supplementation at this stage, proper care should be taken to sterilize the supplements with higher doses of formaldehyde. Occurrence of weed moulds and rise in temperature should be monitored.

However, studies conducted at this Directorate, author has found increased yield to the tune of 15-20% (Fig. 10.1). No response/low yields/or crop failure were also reported.

Supplementation at spawning in SMC has been found successful. In colder areas where room temperature remains low during spawn running stage supplementation at this stage becomes boon as increased temperature favours early spawn run.

Supplementation at this stage should be tried with LMC only when the compost is perfect.

G. Supplementation at Casing (SAC)

In this case, required quantity of supplement is thoroughly mixed in the properly colonized compost just before casing and casing applied as usual. When cultivation is done in racks or shelves spawn run compost is scraping opened, ruffled and required

Fig. 10.1. Button mushroom crop after supplementation

dose of supplement is properly mixed in the entire compost. Compost is re-levelled, pressed and casing layer applied as usual. Increase in yield due to supplementation at this stage with cottonseed meal or soybean meal is over-whelming (15-30% increase) whether tried on LMC or on short method compost. Some of the common supplements for casing are soybean meal and cottonseed meal and the recommended doses for these are 1% fresh weight of compost.

H. Supplementation and Crop Management

Introduction of supplement in the compost temporarily deviates its selectivity from normal, which often involves occurrence of weed mould and high temperature in the compost beds, which may sometimes kill the mushroom mycelium. If temperature rises too high in the compost beds, greater differences in the bed temperature and air temperature are required to be maintained. In certain cases, depth of compost may also be reduced to overcome this problem. Supplementation can be tried successfully in bags (10-12" depth) or in trays (6-8" depth). In case of occurrence of weed mould, the infected portion should be removed and spot treatment with formaldehyde, bavistin or any recommended fungicide can be done. Mould incidence is generally rare when supplements are added at casing.

Compost and casing moisture levels play an important role in determining the benefits of supplementation. Since supplementation increases the yield to the tune of 20-30% of even more, water requirement of the crop would be more. Higher compost moisture in combination with supplementation at spawning proved superior to the treatment with lower moisture level. We have found 68% moisture level as the optimum for supplementation studies.

In India at present, no readymade supplements are being marketed. Number of supplements are, however, commercially available in USA and European countries.

Supplementation is more effective when done at casing, less effective at spawning and gives only average results when done at just before phase-II of composting. Some of the commonly used supplements in market in foreign countreis are Millichamp, Spawn mate, Champ food, which are soya derived products and are often used by European and American mushroom growers mostly at casing getting fairly hih increase in yield.

Further Readings

1. Chadha, K.L. and Sharma, S.R. 1995. Advances in Horticulture. Volume 13, Mushroom. Malhotra Publishing House, New Delhi, 649 p.

2. Griensven, L.J.L.D. 1988. The Cultivation of Mushrooms. Darlington Mushroom Laboratiries Ltd., England, 515 p.

3. Vedder, P.J.C. 1978. Modern Mushroom Growing. Educaboek, Netherlands, 420 p.

4. Vijay, B. and Gupta, Y. 1997. Cultivation of white button mushtroom. Technical Bulletin number. 83p.

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