29. Apr, 2021

Compost Maturity/Germination : Compost Week suggestion

 The length of time it takes to produce mature ready to use compost will vary with the method used and the type of bin  from about a  month to a year , and the intended use of the compost but to do so is quick and simple..

However, most composters do not test their compost, if it looks and smells OK, they use it especially if it is just being used as a mulch. Some will go a little further and carry out a smell test (as discussed in my previous blog). I have always felt that maturity tests where unnecessary on home compost but  there is always a slight change that  immature compost  could kill  or stunt plants. It is also possible that an  herbicide in  the raw products could survive the composting process, remember the horse manure problem. .

A simple Maturity/Germination  test using   used  radish seeds that is quite quick and requires relatively little effort. . A known number of seeds  are sown in a  pot  of the compost to be tested and allowed to germinate. Some methods use  ten seeds per po so that the geminated and mature plants can be counted, and a germination rate calculated. If counting the seeds, I tend to use either ten or multiples of ten to make the calculation of 75% easier although but  most of the time I use a 1.2ml ( ¼ tsp) measure and sow the seeds in sown in a  15cm flowerpot and just estimate whether ¾ have germinated.   It is advisable to use a control sample of commercially available compost or a previous tested batch of home compost as a control. The seeds may need to be watered daily to maintain the moisture level. Radishes are used because they germinate and mature quickly. It should be possible to count the germinated seeds at about seven days and harvest after 4 weeks.

 If about  three quarters  of the seeds germinate  and grow into radishes the compost  is ready and safe to use., they also make this an interesting growing  activity for kids.

If more accuracy is required a more pots should be used, some will use 6ix pots with about 69 seeds for both the test and control samples If the germination rate id significantly lower in the test samples than the control the compost is still immature, and the maturation process should continued

Why not test your (compost) maturity as part of Compost Awareness Week?