CULTIVATION
period) so that, together with well insulated doors, the cold outside conditions cannot cause a lower temperature in the final few metres of the bed near the doors. To eliminate this influence, most mushroom farms in extremely cold Canada have created a covered, enclosed area behind the entrance to the growing rooms.
Steering towards optimal pinhead formation and growth is the most complex
part of the entire process.
Not enough pinheads? Too many farms still experience problems that can severely curb pinhead growth. Problems with ammonia, for example, can negatively affect the compost homogeneity if reducing the ammonia content is difficult. From time to time, this phenomenon also occurs at even the most professional companies. There is a variety of causes. One of these is an incorrectly calcula- ted cold start before the composting process started. This means that the C/N ratio was not optimal, and there was too much chicken manure in the straw, for example, or not enough straw was used. This often causes too high compost temperatures during pasteurisa- tion. If the compost temperature rises to above 60°C, too many important bacteria will be destroyed, so ammonia cannot be converted into proteins, or not properly. Many large composting companies often use laboratory analysis and make an approximate guesstimate of how many loaders full of chicken manure should be mixed with the bales or bulk loads of straw or tons of horse manure. This estimation is often based on the wide experience of the responsible managers.
Another problem with ammonia could be traced to suboptimal aeration through the compost during the phase II process in tunnels This can be caused by too much compost per m2
of
tunnel surface, too wet compost with a short structure, or by a poorly filled tunnel. The undetected presence of moulds can be another reason behind uneven pinhead growth. These moulds not only significantly slow production but also affect uniformity, which also impacts on the final yields. If diseases are present in the compost such as undesirable moulds, you will quickly notice discoloured and dying pinheads on the casing soil. However, if all the pinheads are white and hard, but too many fail to develop into mushrooms, there is another cause, possibly ammonia-related.
Grower in charge
Ammonia-associated problems and diseases quickly and easily cause a lack of uniformity in the growth pattern. This often starts with delayed mycelium growth in the compost and colonisation of the casing soil, and later delayed pinhead outgrow. A too high pH, which also happens occasionally and often without a clear
32 MUSHROOM BUSINESS
reason, usually also leads to delayed and uneven growth.
A good grower can usually exert a considerable influence on mushroom growing. A grower should know how to analyse and interpret the data collected during cultivation, and doing this comes with years of experience. If just one small aspect is not optimal in the cultivation process, delayed growth is often the first symp- tom. Often the compost does not smell sweet enough and it is not covered enough with white mycelium. Sometimes, the compost may look nice and white, but does not smell sweet. Later on, huge differences will be seen in the growing room - ranging from mushrooms almost ready for picking to small patches of pinheads that have failed to develop, but also large areas where growth seems difficult. Another common phenomenon is too many pinheads dying off, before the end of the first and second flush has been reached. This is usually down to poor compost quality. In a healthy crop of mushrooms on good quality compost, you shouldn’t see or feel any dead or too soft (dying) pinheads. In a healthy crop, many pinheads are already growing for the following flush before the final mushrooms of the current flush have been picked.
Other influences on pinning Apart from the importance of working with homogeneous materials, other factors also influence pinhead formation and growth. Steering towards optimal pinhead formation and growth is, in my opinion, the most complex part of the entire process. Every grower will acknowledge that there is a fine line between too few or too many pinheads. Situations can occur where the first flushes developed perfectly well for weeks in succession before suddenly there is a cropping cycle with too many or too few pinheads - even though as far as the grower is concerned all the processes were followed in the same way, and there were no apparent problems. This confirms that no two cropping cycles are the same. There are certain contributing factors such as higher or lower compost activity and weather influences (even on farms with a good climate installa- tion), but often even the most experienced grower does not understand exactly why more or fewer pinheads suddenly appeared. Experi- ence and alertness play a crucial role here. The more homogeneous and uniform all facets of mushroom growing are, and the better the compost quality (‘more forgiving’ as the Americans say), the easier it is to steer growth properly. The best way to do this is using the air temperature. Remember that even 0.1°C higher or lower influences the number of pinheads! A
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