ISHS Acta Horticulturae 172: Composts as Horticultural Substrates
PREPARATION OF COMPOST FOR THE PRODUCTION OF MUSHROOMS IN THE NETHERLANDS |
| Author: | J.P.G. Gerrits |
| Abstract:
In 1983 80,000 tonnes of mushrooms (mainly Agaricus bisporus) were produced in the Netherlands by a total of 820 growers. All the necessary compost is made by two firms. The total production is about 10,000 tonnes per week of which 80% is produced by the Cooperation and 20% by a private enterprise. The most important basic material is straw-bedded manure. If this is not available in sufficient quantity, straw compost is used. In winter this amounts to 20%, in summer to 50%. In the past a great many materials were added to a compost such as malt sprouts, cotton seed meal, urea, ammonium sulphate, calcium carbonate, superphosphate and gypsum. Straw compost was additionally supplemented with a range of minor elements. Research has fundamentally changed this formulation. Nowadays chicken manure is used as the exclusive organic N source. The only inorganic supplement left is gypsum which turns out to be of utmost importance. Two formulas are in use now, one for horse manure compost and one for synthetic (= straw) compost. A tonne of horse manure is supplemented with 100 kg of chicken manure and 25 kg of gypsum. The amount of water to be added varies from 200–800 l per tonne. This results in 900–1300 kg of compost. Prewatering takes about a week followed by the proper composting in windrows, which takes another week with a turning every 2–3 days. On average an optimum ammonia content in the compost pile is achieved with 100 kg of chicken manure. If horse manure contains much straw. more chicken manure has to be added and vice-versa. Mushroom production is best when the NH4 content of the compost is 0.4% at the end. In that case the N content (determined in dried samples) is fairly constant from the beginning to the end. For synthetic compost preferably wheat or rye straw is used. Per tonne 600–900 kg of chicken manure, 75 kg of gypsum and about 5000 l of water are added, resulting in 3000 kg of compost. The straw is first mixed with 2/3 of the chicken manure, watered en gets heated for 7–10 days. The purpose of this pretreatment is to make a product similar to horse manure as it leaves the stables. Gypsum decreases the pH of the compost. This is particularly important if the NH4 content is high. The role of ammonia and consequently ammonification and N immobilization in the compost needs further study. After the outdoor composting in windrows the compost is pasteurized and conditioned in layers (in a mushroom house) or in bulk (in tunnels). The time of this process depends on the NH4 content in the compost. | |
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