COMPOSTING


immediately after adding the chicken manure, as this is when the bacteria in the mass It is very important to fill the bunkers using a bunker filler, so the compost is loaded as homo- geneously as possible while retaining lots of air in the mixture. Some companies even continue composting in windrows for a few days after their bunker process if there is insufficient bunker capacity.


Chicken manure being evenly levelled on a windrow.


much is the compost compacted by the compost turner? How long does the windrow process take? Is windrow composting combined with bunkers? As each composter will answer these questions differently, the end results will vary accordingly.


With windrow composting, mixing raw materials


containing nitrogen, is


vitally important.


Windrows combined with bunkers There are companies that produce compost using a combination of windrows and bunkers. They have a mixing line and form the windrows using the mixed raw materials without pre-wetting. In this case, pre-wet is actually combined with composting. Depending on the quality of mixing, the compost temperature will increase slowly or slightly faster. These companies have good expe- riences with turning the windrows daily using a compost turner for the first five days. This is done to mix the raw materials better, but more importantly, to introduce more oxygen into the mass. During this daily mixing (no more than five days, one mix daily) some water can be added to the compost. As the compost heats up, the action of bacteria will slowly start to soften the straw or hay from day one, so it can absorb water more easily. This is why adding an extreme quan- tity of water during the first mix over the mixing line is unnecessary, as hard straw cannot absorb water (see also the article in MB99 on straw). In addition, adding a lot of water if chicken manure is mixed in is not a good idea The advice ( if there is sufficient space) is to mix in the chicken manure one or two days after forming the wind- row, which means that pre-wet is done for the first one to two days. Any excess water can then drain away. Five days after the first windrow has been made, the compost is moved into bunkers, depending on the capacity and number of bun- kers. The best time to move the compost is


64 MUSHROOM BUSINESS


Windrow composting only Companies that do not have bunkers and have to rely exclusively on windrows will generally have a longer phase I process depending on the quality (hardness) of the raw materials. Some composters dip the straw first in goody water before opening the bales on the same day and forming a windrow. Others dip the straw bales, then leave the bales intact for between two to eight days to allow the straw to soften. Leaving the dipped bales for longer than two days can be risky and stimulate a too high temperature incre- ase (depending on how firmly the bales are com- pacted) which combusts too much lignin. In addition, leaving them for too long can also cause a serious oxygen deficiency for too long. This just goes to show how practices differ from company to company! The start of the process can already impact significantly on the final compost quality. And this quality, to repeat the well-known mantra, has a huge influence on mushroom production in turn.


Mixing in windrows


With windrow composting, the way in which chicken manure or other raw materials that contain nitrogen are mixed is vitally important. When are these materials added and how? If they are added at the same time as the dry straw, hay, or other carbon raw materials, the mixed raw materials will heat up much slower than if a windrow is pre-wet first, or if the straw bales are left for a while after dipping.


Another consideration is how chicken manure is mixed to the straw. In a conventional windrow system, the best way is to distribute the chicken manure over the top of the windrow and level it evenly. This process must be done very precisely, to ensure optimal mixing. The advantage of levelling out the chicken manure well over the surface of the windrow is that too little or too much can never be given with a correctly calcula- ted cold start formula. To achieve the best possible mixing quality, the advice is to mix two or three times using the compost turner on the same day that chicken manure is added without adding any water. After two days of pre-wet, the straw should normally be wet enough to provide the bacteria with enough moisture until the following day, when


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