Biodynamic Basics: the art and science of making and applying compost

There are many methods for making compost, all with same aim of turning garden waste into broken down organic matter to nourish the soil and feed crops. Biodynamics takes a slightly different approach to achieve this. It believes that cosmic forces have a role to play, and that as well as providing their well known beneficial herbal benefits, its unique compost preparations or activators help to align and harmonise these forces with the innate intelligence of the soil and plant life. Lifelong biodynamic gardener, Hans-Gunther Kern shares his insights and experience.

What defines a biodynamic compost?

It is a process whereby, with the help of bio-dynamic compost preparations, we facilitate the slow and gentle decomposition of a variety of organic materials, together with the integration of soil and other minerals we might have added to the pile – such as basalt (volcanic rock dust), wood ash or quicklime.

In this gradual transformation of all materials, by a rich diversity of microlife (bacteria, fungi and protozoa), and macrolife (springtails, spiders, ants, woodlice and compost worms) that, after 9-12 months, the most valuable stable humus is produced. This, in turn, is usually alkaline has 2-4 times higher concentration of nutrients than the original material, and has the capacity to retain water like a sponge.

The first phase of a decomposition, effected by the microlife, releases  lots of heat and free nutrients, takes typically 1-2 months and creates, what we call an effective humus (acid), with lots of available nutrients to feed the plants. This compost is most beneficial for the heavy feeders.

The second phase of the formation of stable humus (alkaline) takes roughly 7-10 months. This compost is best used to regenerate the soil, for potting mixes and medium to lighter feeders and givers (see detailed description below).

This process and the timing depend greatly on the climatic conditions and the use of more or less nitrogen rich material and the moisture content of the pile.

The benefits of biodynamic compost

Biodynamic compost is special: it helps to nourish the soil life and to inform and regenerate the soil, so that in turn the soil life can feed the plants.Think of it as acting like the leaven in the bread inoculating the soils with nitrogen fixing bacteria, and bringing enzymes and vitamins into the soil for a healthy soil and optimal plant growth. According to research done in Dornach, Switzerland on biodynamic compost, it loses less carbon and accumulates nitrogen and other minerals if built as suggested below.

But there is another equally important aspect that is an essential part of biodynamics, namely the role of cosmic forces and how the various biodynamic preparations facilitate these; in this case, how the compost preparations  ‘sensitize’ the soil organisms and humus in the compost, so that they can better respond to and assimilate the subtle forces streaming in from the sun, planets and the stars of the zodiac to serve optimal and healthy plant growth.

As borne out by experience, soils receiving biodynamic compost support plants found to be more resilient to pests, diseases and severe weather conditions. Furthermore it enhances the nutrient and keeping quality of the crops.

Where is the best place to build a compost pile?

Good compost develops its own warmth and life processes, which means it needs to be protected from direct sunlight or wind and subsequent drying, and from excess water from rain.

I find the ideal place is on the north side of hedges or near trunks of large trees. But beware that it is not in the drip line of the perimeter of trees, where it will be drowned by water and penetrated by feeder roots of the same trees.

• For the best humus development and accumulation of nitrogen fixing bacteria, the best trees are deciduous ones : Birch, Alder, Sloe and Elder. Avoid conifer trees and hedges.
• Make sure that before building the pile you remove all grass or growth, fork open the soil so the soil organisms can invade freely the new organic material piled on top. Alternatively, dig out the top soil to 30 cm and put brush and prunings underneath the pile.

After 2-3 years, I find that the compost turns out in excellent condition, provided you leave a residue of old compost to inoculate the new pile that follows.

What’s the best shape and size?

For the most effective and beneficial development of your compost, for a free standing compost pile, build a dome shaped pile (like an egg cut into two) a minimum of 1m3 in volume (1x1x1m).

If space is an issue, you can create compost in a box on a balcony, inoculated with compost worms. In this case, I suggest every month add the  biodynamic Mäusdorf starter. For wormery starter kits click here.

How to find the right balance of materials?

The secret of getting an optimal compost lies in the right proportion of nitrogen (‘green’) and carbon (‘brown’) rich materials, the best moisture content ,and how well aerated the compost is.

The greener and younger the plant material used in the compost pile, the faster it becomes available to the microbes,  and thus the faster it will heat up and tend to overheat, losing all the nitrogen, which we need to enhance the vegetative growth in our crops. The best example are grass clippings, they overheat and invite the grey fungus called “firefang”.

A useful  tip is to spread, for example, grass clippings not thicker than 10-15cm on a base of stalky, carbon rich material, let it wilt a bit and then add more later.

A good balance is to use by weight 1/5 of carbon rich, stalky material, like old flower heads and weeds which have just started flowering, plus 4/5 of green material (include prunings of ornamentals and hedges up to ¼”/1cm thickness) and layer as described below.

How to build a compost pile?

Sir Albert Howard, one of the early principal figures in the development of organic farming, developed the Indore method of composting in 1930s, which has proven to be the best method to date. This consists of alternate layers of 5cm of fresh, green, moist, nitrogen-rich material, with a fine sprinkling of quicklime or fresh, dry wood ash, followed by 10 cm of carbon rich, stalky, dry material, with a fine sprinkling of the soil from the garden.

Make sure you add sufficient water. Test by taking a mixture of material after watering the pile and squeeze the material. If one drop of water emerges, it is the right moisture in the pile for a healthy process of decomposition and composition.

If it is a free  standing pile, build up the edges a bit higher, so the pile will collapse towards the centre as it decomposes.

My basic, foolproof method.  I have found that just layering all weeds, crop residues, prunings, sweeping from paths, garden soil, wood ash in a pile of 1.5 x 1.5 x 1.2m height over a period of half a year works really well. I then add the biodynamic compost activators (preps), burying them each into the pile, and in 9 months all has turned usually into black soil and humus, without shredding or mixing the materials or turning the pile. It’s like magic and saves much work.

Make sure you always cover the pile with soil or old compost and a thick layer of straw or any other dry material to protect the pile from the weather.

What happens if my compost goes stagnant or seems putrid?.

This is a common complaint, especially when new to making compost. If for some reason your material was too rich in nitrogen, too wet and lacked ‘brown’ material to supply carbon and structure, it might well turn into a smelling, anaerobic putrid mess.

Prevention is better than cure, so the answer is to keep track of your compost process, especially in the early stages. Put a smooth, straight stick into the core of your compost pile and check every day for the first two weeks of building a compost pile, noting  temperature, moisture, colour and odours.

Too wet :

• If your stick stays lukewarm, is wet and shines with moisture, and  smells putrid , add lots more woody material to aerate it  better, or turn it and add more ‘brown’ carbon rich material to it.

Too dry:

• If your material contained too much nitrogen rich, fresh, young plant growth, such as grass clippings or leafy hedge prunings, you will find your stick becomes dry, is hot to the touch, and has a greyish or rusty colour.

i.e. it has got too hot, too fast and has burned up all the nitrogen in your pile.

Before that happens, either trample on the pile to eliminate some of the air and slow down the decomposition process. If that is not enough,  water the pile liberally to cool down the pile, then eliminate more air.

If you only caught the pile after it overheated, add 10-20 litre/m3) of liquid fertiliser made from stinging nettle or comfrey plants.

When the composting process has finished after 9-12 months, either apply to the soil or cover it and let it dry out to store it for future use.

When is your compost pile ready to use and for which purpose?

It’s not generally appreciated that you can use your compost at different stages  depending on what you want to use it for. For example:

For long term benefits – to regenerate and improve your soil, or to use in sowing and potting mixes, use a well rotted compost, which is at least 9 months old.

To feed your crops and plants in the garden – use your compost after 1-8 months of composting as outlined below.

For the best results, to activate the soil life, and provide a ‘booster’, where possible, apply the 6 biodynamic compost activators (preps) or Mausdorf starter 2 weeks before applying the compost  to the soil. If using dry stored compost , wet it liberally first as well as applying the preps.

In my experience for best results for your crop yield, health and nutrition use your compost:

After 1-2 months for heavy feeders like:

Crucifereae: Cabbages Cauliflower Broccoli

Solenaceae: Potatoes, Tomato, Pepper, Aubergine, Chilli

NOTE Cucurbitaceae: Cucumber, Melon, Courgette, Pumpkin, Squash are an exception. For this family use the compost after 6-9 months.

Use after 4-6 months for medium feeders like:

Liliaceae: Leek, Onion, Garlic, Shallots

Chenopodiaceae: Spinach, Swiss Chard (Beetleaf), Perpetual Spinach, Beetroot

Crucifereae: Kale, Brussels Sprouts, Kohlrabi

Compositeae: Lettuce, Endive, Sugarloaf, Radicchio

After 6-9 months for medium feeders or ‘givers’ like:

Leguminoseae: Broadbeans, Dwarf and Runner Beans, Peas,

Green Manures Alfalfa, Vetch, Clovers, buckwheat, Flax, Agricultural Chicory, Phacelia, Mustard.

After 9-12 months for light feeders like:

Umbelifereae: Carrot, Parsnip, Parsley Root, Scorzonera, Salsify

Liliaceae: Shallot, Chives

Crucifereae: Swede, Turnip, Radish

How much compost to apply?

I like to work and grow my crops on standard beds approx. 6.5 m long x 1.5 m wide, which is roughly 10m2. It’s not a precise science, but for a standard bed, the following is a useful yardstick: 

Heavy feeders: 1-1 ½ wheel barrows/bed

Medium feeders: ½ – ¾ wheelbarrow/bed

Light feeders or givers: ¼ -1/2 wheelbarrow/bed

Light feeders: 1/2 wheelbarrow/bed

Finally, always use suggestions given as a guideline – the beauty of gardening is that your own experience is what matters most. Remember, too, that your soil is constantly evolving and each batch of compost is unique. The more you observe, make your own discoveries, and learn from your experience, the more easily you’ll be able to sense and judge what is right for a particular situation, and the more in harmony your garden will become. 

Most of all enjoy your compost !

Ed Note: The Biodynamic compost activators ( preps) can be purchased from the BDA’s online shop here. These are a set of 6 herbal preps and are used when you can build a heap all in one go. For gardeners who use a compost bin and who are continually adding in new material then the Mausdorf compost starter is recommended. This has the bonus of being in a dried form so can be stored easily. As well as guiding the compost breakdown it is a great multi-tasker and can be used as a spray for your soil, as a root dip etc.
Barrel prep ( also available from the online shop) has exactly the same ingredients and properties as the Mausdorf starter but as it is moist, it needs to be stored carefully to ensure its “life forces” are maintained; in a similar manner to the Horn Manure/soil activator.
Click here for more info about the Barrel prep /Mausdorf starter, its benefits, and how to use it.