Bulking agents such as wood chips or ground bark are often included in the mix to increase pore volume. During the decomposition process, the material tends to collapse, with a reduction in both total and pore volume. The initial physical properties must be suitable to ensure adequate aeration during the whole breakdown process. Mixing restores the pore volume for a short period, but the main benefit of mixing is to transfer the outer material to the centre of the pile where decomposition takes place. The Resource Management Act is beginning to force communities to set up sustainable waste management systems.
Landfill is no longer the simple solution.
Composting is now being recognised as a viable alternative to other disposal methods. In countries with higher population densities and greater wealth than ours, it is economically feasible to operate high technology composting systems to process solid organic waste. These systems are fully enclosed and use mechanised handling equipment and are extremely impressive. In New Zealand a lower technology system is more appropriate. We have the land area to site open- air composting operations where they do not create a nuisance and we can produce very good compost using relatively simple machinery.