MARIA THUN’S BARREL COMPOST 502-507 is a spray used by some Biodynamic wine-growers. It was developed by Maria Thun and is simply a speeded up form of solid Biodynamic compost 502–507 and which is applied to the land in infinitely smaller volumes than the latter and in liquid rather than solid form. The barrel compost spray 502–507 is seen as a helpful primer for land converting from conventional farming to biodynamics, sometimes preceding even the very first application of horn manure 500, thereby initiating healing processes for soils by reversing the erosive, hardening tendency soluble fertilizers have of turning clay (aluminium silicate) back towards rock. Bouchet p 67

See also | Peter Proctor’s Cow Pat Pit which uses bricks rather than barrels to lin the pit.

OTHER NAMES FOR BARREL COMPOST | In Germany it is called Pfladenpräparat (‘cow pat preparation’), in France it is called le compost de bouse, and in Australasia Barrel compost has numerous other names – barrel prep, barrel manure, biodynamic compound prep, dung compost spray, manure concentrate – but has one main function, offering an easier, quicker way of getting the biodynamic compost preparations 502–507 onto vineyards rather than waiting the six to twelve months compost piles need to mature. is is especially appealing to winegrowers with large or steep vineyards, or who are unable to find enough of the right compostable material.

Barrel compost should not be viewed as a long-term substitute for solid biodynamic compost which imparts more profound, longer-lasting effects on both soil structure (substances) and soil vitality (forces). Barrel compost 502–507 softens compact soil by bringing air into it, balancing soil nutrients, improving soil structure, decomposing organic matter (e.g. cover crops), stimulating humus formation and generally improving soil quality. It can also be sprayed on animal bedding before this is composted (Pierre Masson, 2014 p78).


Barrel compost was developed in the early 1970s by Maria Thun. Its precursor was the ‘collective preparation’ or Sammelprepärat developed in 1927 by Max Karl Schwarz, one of the first German farmers to adopt Rudolf Steiner’s biodynamic ideas. Schwarz made his collective or ‘birch pit’ preparation by lining a long pit dug into the ground with birch poles and locating it near the barn in which farm animals overwintered. eir manure was emptied into the pit and sets of the biodynamic compost preparations 502–507 were dropped in. e manure was left to compost for several months and then spread on the farm in solid form, and the pit was refilled with fresh manure.

Rudolf Steiner made no reference either to barrel compost or a collective/birch pit preparation in his 1924 Agriculture course.


The main constituent of Maria un’s barrel compost is fresh cow manure. is can be collected in the same way as for horn manure 500, although just before her death un suggested manure from pregnant cows be used.10 The pats can be up to two days old.

To 50 litres of cow dung, add 500 grams of basalt as coarse grains, grit or finer powder and 100 grams of finely crushed, sun-dried (not oven-dried) eggshells. ese are then mixed together for an hour. Using shovels, this can be done either in a wheelbarrow or in a wooden barrel stood on one end with the other knocked out, or on a board placed on the ground. Stir from the outside in. Thun says the mixture should have become ‘one dynamic whole’, resembling a big cow pat with a slightly dilute colour. Peter Proctor says farmers can become bored during the mixing or stirring and not mix as well or long as required, but a good stirring will ‘make all the difference’ to this preparation’s quality. Others say using a cement mixer is easier still…

The mixing can be carried out under a descending moon and when the sidereal moon stands in a root/earth constellation: Virgin in the northern hemisphere and either Goat or Bull in the southern hemisphere.

Half of the manure, basalt and eggshell mixture is then placed in another barrel stood on one end, but with both ends knocked out. is would have previously been dug into a hole in the ground, not quite half as deep as the barrel, with the excavated earth piled around the part of the barrel poking up above ground level. e barrel is left open at both ends so the contents within may receive both earthly (lime/ calcium) and celestial (silica) forces. e five solid biodynamic compost preparations 502–506 are dropped one by one and separately into the mixture, with stinging nettle 504 usually placed at the centre. en the remaining half of the manure, basalt and eggshell mixture is placed on top, and it too has a set of solid compost preparations inserted. Finally, a liquid mixture made from five drops of the valerian 507 preparation stirred for ten minutes in a litre of water is poured over the top.11 e barrel is then covered with its lid.

Twenty-seven days or one sidereal month later, when the descending, sidereal moon has returned to the same earth/root sign under which the mix was prepared and added to the barrel, the barrel’s contents are aired by turning them briefly with a spade. un says that after another two weeks the barrel compost will be ready; Bouchet says to wait another sidereal month. Some growers leave their barrel compost in the barrel for several more months or until it is needed for use, adding an extra set of preparations whenever the barrel compost is turned. Some New Zealand growers leave their barrel compost (or, more usually in their case, Peter Proctor’s cow pat pit (CPP) Spray 502–507) up to one year for it to experience all four seasons.12

Leaving the finished preparation in situ risks allowing worms to devour it, however. e finished preparation should resemble very rich, dark, fine soil with a clean and intensely earthy smell. It is stored in the same way as horn manure 500.

The role of eggshells and basalt

Thun decided to add calcium-rich eggshells to her barrel compost because she found that oats, celery and tomatoes grown on limestone soils had healthier root systems and contained fewer residues of the radioactive Strontium 90 left by America’s 1958 atomic bomb tests compared to similar plants grown on sandy (siliceous) granitic soils. Biodynamic winegrowers are therefore encouraged to keep chickens from which to source fresh eggshells for this part of the preparation.13 un says basalt’s role is to support those living organisms and processes in the soil involved in or which work towards decomposition, and thus promote humus formation. Henderson points out that in chemical terms this leads to the formation of more clay minerals, which encourage humus formation (clay-humus complex).14 e basalt acts in a nitrogen-fixing capacity when even more finely ground than grit, she says.

Another way of looking at the addition of eggshell (calcium) and basalt is that they represent two basic soil types: basalt is of ancient volcanic origin and comes from inert magma within the earth’s mantle and amounts to embryonic, new soil,15 like infant clay;16 calcium is a geological baby present in limestone-rich soils formed by marine deposits from living creatures within the last several hundred million years. From a biodynamic perspective the eggshells provide the lime polarity (crop growth) while basalt provides the balancing silica polarity (crop taste). Christian von Wistinghausen used volcanic ash instead of eggshells for his version of Maria un’s barrel compost, the Mäusdorfer Rottelenker, which he named after his home town of Mäusdorf.

Stinging nettle

Adding finely chopped (2.5 centimetre) fresh stinging nettles to the manure mix appears to regulate plant health and growth, possibly by stimulating greater root growth and improved root health. The nettle should be harvested as it is about to flower.