Susan Wakeman wrote:From the perspective of soil microbiology, how would you rank the effectiveness of the following composting methods? I've ranked them in ascending order of work or attention required.
First I want to thank you for this question and I also want to give big kudos to SuBa for a very good post about this subject.
Your first line indicates you are interested in soil microbiology and building the soil full of microbiology.
Then you delve into methods that are listed in amount of laziness allowed but with still good results of compost making.
These are really two separate things, you either build soil or you do lazy man's methods of composting, they will eventually come to a point of convergence but it will be a while before this happens.
The best way to improve soil microbiology or the microbiome of your soil is to make good compost.
Good compost is balanced between nutrients and microorganisms, it usually comes from hot composting methods and it should be noted that using bokashi or biodynamic methods indicates that you are going to be adding these to a hot compost heap to reap maximum rewards for your soil.
Sheet mulching is more for controlling weeds than for building the soil microbiome, that occurs as a side bar type process.
Cold composting is more along the lines of leaf mold making than good, microorganism rich compost.
Worm bins give you a ready to use manure, you simply apply these like a natural fertilizer.
Hot compost is the method used for building good, oxygen rich, microorganism rich, nutrient dense material for applying directly to soil or making compost teas for increasing Microorganism numbers in your soil and protecting plants from disease or infestation.
Methods to create good things to add to a hot compost heap for the purpose of increasing the numbers of microorganisms are:
"the preparations most call biodynamic" (biodynamic is a registered trade mark and the preparations they promote were created by Steiner in the 1920's at the request of some farmers.
Use of Steiner preparations is a very good way to build Microorganism rich compost, but first you have to make the preparations before you add them to the working compost heap, this adds large amounts of time to end goal.
Making bokashi (fermented vegetative scraps) requires the time to ferment then you need to aerate this soup and then you add that to the working hot compost heap. again, time is consumed to get to the end product.
Simply making hot compost will grow the multitude of microorganisms we are looking to add to soil to make it really good soil, the other things are great for boosting these numbers but they are not necessary if you build well constructed compost heaps.
The main purpose of turning compost is to get air into the whole of the heap, compost settles as it decays which means that air pockets are getting smaller and smaller while this happens.
I turn a heap usually three times, but you don't really need to turn it, you do need to get air into the whole of the heap.
This can be done by using a piece of 3/4" pipe by ramming it at an angle all the way to the soil beneath the heap, go all around the heap from about 1 foot above the soil level, then repeat every foot above that first round until you are at the top of the heap.
This method of adding air takes far less effort than turning (unless you are doing windrow style composting in which case you should have a mechanical compost turner).
The only other requirement is that moisture remains constant, moist not dripping is the key here, misting works best for filling this requirement.
Redhawk