SPAIN
oxygen deficiency during pasteurisation. Most of the companies we saw have their own large, wood-burning installations to generate steam. To produce and spawn the blocks made from pasteurised straw (phase II) the same machines are mostly used in Spain, with a filling hopper in the centre and blocks being pressed on two sides. The blocks weigh 15 kg each. The spawn is dosed and added to the straw as it is being formed into blocks, at a rate of about 5% per ton of substrate. A little chalk powder is added to reduce the stickiness of the spawn so it spreads evenly through the substrate. The blocks are then stacked on pallets and transported to the growers.
Shitake on shelves at Hongos Fernandez.
Recently experiments have been run with growing shiitake on straw blocks. A lot of sawdust is added in this case to the substrate mixture and a higher ratio of spawn is used (7%) as shiitake mycelium is slower to colonise the growing medium than oyster mushrooms. These blocks are incubated centrally for four weeks and then taken to the growers.
substrate). The production process that makes this substrate is similar to elsewhere in Spain. A basic blend of 80% dry wheat straw and 20% maize straw is chopped and wet using goody water to encourage a heating process that will start to eat away at the waxy layer around the straw as soon as possible. This phase I period usually takes about three days, during which the mixture is turned at least once by a front loader. Straw is very dry and hard in Spain, so caution is necessary as once the decomposition process kicks in the structure can be lost very quickly. The straw is also very short, as the hot Spanish summers limit growth compared with more temperate climates (North Europe). No products are used in Spain to restrict the length of the straw.
After this phase 1, the wet mixture is loaded into a tunnel, fitted with a slatted concrete, spigot floor. The tunnels are doubled-ended so they can be filled from the outside by a cassette system and emptied from the inside by a loader before the substrate is pressed into blocks. There are no mats or nets in the tunnels, but the material rests instead on the slatted floor and is aerated by the spigots. During phase II (pasteurisation) in the tunnel, steam is applied to raise the temperature of the straw to 65 degrees Celsius and maintain it for 24 hours, after which the tunnel is cooled to 25 degrees. This process takes a total of three to four days, depending on the time required to press the blocks. In Spain steam is mainly relied on for heating up and not the activity of the mixture itself as in the Nether- lands, as composters are afraid of creating an
36 MUSHROOM BUSINESS
Farms Agruset Our next destination was some of the farms owned by members of the Agruset cooperative: Hongos Fernandez Guridi and Micotec S.A. The substrates produced by the cooperative are used on these farms to grow various varieties of mushrooms. What you notice in Spain is the very extensive nature of mushroom growing, except that is for bottle systems. This means a lot of growing rooms and very long cropping cycles. In addition, the rooms where oyster mushrooms and shiitake are grown often have minimal climate conditioning. This means that the harvest and yields are not always predictable. During out visit to Spain there was a shortage of oyster mushrooms as, in the preceding weeks, a sudden temperature rise meant the substrate
Jorge Calvo (Sylvan) and Ulrich Groos (right) organised the trip to Spain.
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