The CAC-ing technique (means Compost Added at Casing) involves the application of small amounts of fully colonized by the mushroom mycelium, (3rd phase) compost to the casing soil. The technique was developed in Ireland during the 1960s and reported for the first time in 1972 by MacCanna and Flanagan.
The CAC-ing technique has several advantages, and the most important are:
- The casing soil incubated more quickly by the mycelium, there is no need to ruffle anymore;
- The casing soil evenly covered by mycelium and cause more uniform distribution of mushrooms on the bed surface.
- The first flush appears earlier by 3 to 4 day, the shorter schedules enable more cultivation cycles per year. The time gain depends on the amount of added compost.
- This method gives considerably higher mushroom yield.
In the CAC-ing technique, it is vital that the compost mixed into the casing layer is well run and contamination-free. In practice, use amounts between 250-500 g/m2 growing surface (it depends on the casing soil), it makes no sense to use higher doses, because too much compost can inhibit the fruit body formation. A uniform distribution of material on the casing is vital for the success of the CAC-ing technique, so the easiest way the CAC-ing to spread incubated compost to growing bed surface and mix it through the casing soil. If use too much compost to CAC-ing or the surface of casing soil is highly compacted by watering, ruffling may still necessary. The advantage of this solution is the risk that it could contain competitors (especially Trichoderma species). If the compost is infested, but no symptoms are visible yet, the grower could easily spread the disease himself during CAC-ing. (Geösel)
Other precautions to be followed are:
- use the same spawn strain for the casing as for the compost;
- avoid the use of compost that has been overheated;
- remove pieces with black spots or that are excessively dry;
- ensure exclusion of pests and diseases and discard material if it is positive for contaminations such as the presence of nematodes;
- exaggerate at all times the hygiene conditions.
Casing spawn can be bought from spawn manufactures. It is a material with similar characteristics to casing soil and colonized by mycelia (the same strain that the compost contains). Mixing 30 l/150 m2 casing spawn in the casing soil speeds up colonization and the first mushrooms can be picked on the 16-18th day.
For more information check these publications:
- A Study of Compost Added to a Casing Technique in Agaricus bisporus Cultivation from Phase III Bulk Compost – Diego Cunha Zied1 and Marli Teixeira Almeida Minhoni
- Modern Mushroom Cultivation Technologies – András Geösel and Anna Szabó
- Mushroom Cultivation – Peter Oei
