A second type of activator, sometimes described as an inoculant, provides additional microorganisms to boost the decomposition process or are enzyme activators that when mixed in water are sprinkled
on the organic material to “activate” the composting microbes. Both methods are said to speed the decomposition process. The theory is that the addition of an inoculant containing the bacteria and fungi at the
stage of decomposition that they are needed will speed the process of decomposition and lead to the all-important increase the temperature of the composting material.
Such a kick
start would also be useful when starting a cool bin as the contents are likely to be less well balanced than in a layered hot compost bin or if it dries out during a hot spell.
Fungi and bacteria are certainly necessary
to start and continue the composting process but the necessary organisms are readily available on the organic material being added to the bin and in the soil or the compost from another bin.
However, there the use of inoculants
is controversial .There are those who argue that the application of additional microbes to the compost heap, by means of an activator, makes little difference as the organisms are already in the organic material and quickly multiply to the limit
that the bin conditions allows. Tests on bacterial inoculates recorded in Rodale`s Complete Book of Composting and the Guide to Composting published in the nineteen seventies gave completely negative results when composting city refuse the additives
failing to make the composting any quicker than composting without the inoculant allowing the indigenous organisms to work unaided. .
The addition of “indigenous” microbes to a new heap or bin by
seeding compost from another bin at a more advanced stage of decomposition is now a tried and tested method When mixed thoroughly this will provide the “kick start” necessary and reduce the time lag before the bin reaches the thermophilic operating
temperature. However, the time saved when seeding a new hot composting bin is relatively small as a well-made layered bin should reach 400C in five days. This type of kick-started compost is sometimes referred to as accelerated composting
There have been a number of papers published on the use of inoculants when composting but relatively few when using home composting. The results are variable.
and Nissaikla looked at the effects of microbial inoculation with two commercial inoculants and mature compost on the composting of household organic wastes (food scraps and dry leaves) using passive aeration compost bins. The
study showed that mature compost can be used as a seed starter to improve composting and that while it was not necessary to add commercial inoculants when composting inoculation with MC had a positive effective even though the improvement was not
Nair and Okamitsu (2010)
used Effective Microorganism (EM) and Trichoderma sp. in the composting of kitchen waste. They found while inoculants are not essential to accelerating composting EM inoculation enhanced the reproductive rate of earthworms.
A study by Abdullah et al. (2013)
using a solution of mixed bacteria as starter culture when composting kitchen-waste found no apparent differences when composting with an added starter culture.
Two papers by Van Fan, et.al. published in 2017
and 2018 gave very interesting results. the first looked at 14 studies evaluating the effect of microbial inoculants on the organic fraction of solid wastes ( mostly food wastes) and 11 studies of the effect on lignocellulosic wastes (mostly yard wastes)
while the second looked at home composting
In the first study 38% of the cases using microbial inoculants showed a positive impact of inoculation on the composting of the organic fraction of the solid wastes. In the
case of lignocellulosic wastes 80% percent showed a positive impact .They noted that the greater positive impact of inoculants on lignocellulosic wastes composting was due to the presence of enzymes breaking down the more decay-resistant lignin compounds.
An evaluation of the use of Effective Microorganisms in home scale organic waste composting by Van Fan et al in the Journal of Environmental Management looked at their use during home scale composting of food waste, rice
bran and dried leaves. The results were compared with and without the addition of EM. It was found that composting with EM achieved a slightly higher temperature at the early stage and that less odour was produced. The humification process was enhanced.
Composting and Microbilal Inoculants BioCycle.net https://www.biocycle.net/2019/02/01/composting-microbial-inoculants/
Somjai Karnchanawong & Siriwan Nissaikla (
2010 ) Effects of microbial inoculation on composting of household organic waste using passive aeration bin International Journal of Recycling of Organic Waste in Agriculture
Nair J, Okamitsu K (2010) Microbial inoculants for small scale composting of putrescible kitchen wastes. Waste Manag 30:977–982
Abdullah N, Chin NL,
Mokhtar MN, Taip FS (2013) Effects of bulking agents, load size or starter cultures in kitchen-waste composting. Int J Recycl Org Waste Agric 2:3. doi:10.1186/2251-7715-2-3
Fan, et.al. published in 2017 and 2018
Van Fan, Y., et.al., “Efficiency of microbial inoculation for a cleaner composting technology”, Clean Technical Environmental Policy, 20:517-527, 2018.