raw materials before they are mixed together. That is what pre-wetting can achieve. If diffe- rent raw materials of (too widely) varying degrees of softness are mixed, there is a big chance of producing non-homogeneous com- post. But pre-wet can also benefit companies that only use wheat straw.
A homogeneous start to the process is crucial. For example, in Spain I saw several composters in the same region, all using ‘the same’ raw materials, including wheat straw, chicken manure and gypsum. Some of them did not pre- wet. The difference was interesting; companies that did not pre-wet had a slower temperature increase after the straw was mixed with chicken manure than companies that did pre-wet before mixing chicken manure in the straw. The resulting productions were practically identical on average. However, that also greatly depends on the mixing method, especially on companies that did not pre-wet as without pre-wetting, chicken manure does not stick to the straw as easily.
Advantages of pre-wetting What is actually the advantage of the pre-wet- ting besides making the softness of any diffe- rent raw materials as homogeneous as possible? A good pre-wet process makes the straw soft and sticky. Dry chicken manure with a fine texture will stick well to soft straw provided no water is used when the chicken manure is mixed with the straw. Another advantage of pre-wet- ting beforehand, is that fewer bunkers are needed. That doesn't mean that aerating the straw during pre-wetting wouldn't be better. An aerated (spigot) floor is obviously cheaper than a bunker.
If no pre-wet system is used, it is vital to mix the raw materials perfectly (but perfectly mixing pre-wet straw is just as important!) because dry chicken manure - as said - does not stick to the hard straw particles easily. Very intensive mixing is necessary if 100% straw is used. In the Netherlands, the most usual blend contains around 85% horse manure. As horse manure is already rich in nitrogen, the concentration of chicken manure needed is logically much lower.
Wetting straw, then placing it on a non-aerated floor is far from ideal.
Bales stacked too close after dipping; plus dry straw bales not acceptable with dipped bales.
For instance, at CNC Grondstoffen, liquid chicken manure is used. This has a different and positive influence on mixing the chicken manure, provided that the chicken manure has been properly dissolved.
Various systems
Pre-wet comes in various guises. For example, some companies dip the straw bales (two minu- tes of dipping is usually long enough, depending on the density of the bales) and then leave them ‘to rest’ for a couple of days before loosening the bales. If the bales are left for a while after dipping, it is also important to ensure that the oxygen content in the bales does not drop to 0% otherwise anaerobic patches may form in the
Ò MUSHROOM BUSINESS 15
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48
