Terra Preta

Our Terra Preta Schwarzerde can be used in both field beds and raised beds. To ensure long-term fertility for all crops, we recommend a layer thickness of 20–30 cm combined with a permanent layer of mulch. Almost any organic material can be used as mulch, e.g. grass clippings, wood chips or our organic fiber Bio Faser.

When used in raised beds, the lower section can be filled with existing soil or our organic raised bed soil Bio Hochbeeterde. Layering, as practised in hugelkultur, is not recommended here, as this would simply require regular top-ups of Schwarzerde. As a general rule, the soil ecosystem should be disturbed as little as possible by digging (no till).

Our Terra Preta Schwarzerde was developed over many years of trials, modelled on the original Terra Preta, in collaboration with numerous recognised institutions and scientists. The reason for its long-lasting fertility, when used correctly (see also How do I use your Terra Preta Schwarzerde correctly?), lies in the soil’s special composition and its extremely diverse microbiology. This combination creates a self-sustaining soil system which, when combined with a permanent organic mulch layer (e.g. our organic fiber Bio Faser), becomes even more fertile over the years.

If you’re planning a complete outdoor grow cycle using only water with our hemp soil Hanferde and don’t have a garden bed or raised bed (where you could also use Terra Preta Schwarzerde) available, choosing the right pot size is one of the most important factors for a successful harvest. As a general rule in outdoor cultivation (even more so than indoors), the motto is: the bigger, the better.  The exact choice of pot size depends largely on whether you intend to grow photoperiodic or auto-flowering plants. Autoflowering plants can certainly produce decent yields even in fairly small pots of around 15 litres without fertiliser (although it has also been shown here that the expected plant size and thus harvest quantity increases with pot size, partly because flowering is triggered significantly later in larger pots), whereas photoperiod plants, depending on their vegetative growth period, require several times this pot volume to be supplied with nutrients until autumn. This leads to the second important factor, which is the start date, particularly for photoperiod plants. If you begin pre-cultivation as early as spring, possibly even indoors, this means a vegetative phase spanning several months. Photoperiodic plants usually only begin to flower in mid-August, shortly before the natural day-night equinox (known as the equinox, i.e. the switch to a ‘12/12 light cycle’ caused by the sun in September). Depending on the strain, it often takes until late October for the plants to reach maturity. This means that the earlier you start and the longer your variety takes to mature, the larger the pot you should choose. In any case, whether indoors or outdoors, an organic mulch layer is essential, e.g. made from our organic fibre Bio Faser. This protects the soil from UV radiation and makes watering easier. (Check out Why should I mulch every soil?).

Pieces of wood are a natural component of our compost and do not constitute a quality defect. All our products are screened using a trommel screen during processing. A specific mesh size is used to remove coarser particles. However, individual pieces of wood may remain in the product if their diameter is smaller than the respective mesh size. This is due to technical constraints and is also a reflection of our conscious commitment to gentle, nature-friendly processing.

We firmly believe that plastics have no place in nature and therefore have no place in our soils either. That is why we invest a great deal of time, money and energy into keeping our products free from contaminants. We deeply regret it when, despite our best efforts, very occasional plastic particles find their way into our products.

In this regard, we would like to give you a brief insight into some of our quality assurance measures:

Selection of raw materials: We use only regional tree and shrub cuttings, as well as controlled sludge (e.g. from jam production and milk processing), to produce our compost. We have made a conscious decision not to use the contents of organic waste bins, as these contain vast quantities of packaging materials, plastic bags and other contaminants.

Inspection on delivery: Unfortunately, it is a widespread social problem that waste is often carelessly discarded in the natural environment. Consequently, tree and shrub cuttings are sometimes contaminated with plastic. The raw materials delivered are always checked by our staff for contaminants. Obvious contaminants such as plastic flower pots or similar items are sorted out by hand before processing. In cases of severe contamination, acceptance is consistently refused.

Technical processing: Despite careful raw material selection and inspection, we cannot entirely prevent isolated pieces of plastic from entering the raw material mix for our compost. To separate these particles before processing into the final product, the finished compost is sieved using a defined mesh size.

External quality controls: Our composts is inspected several times a year by external, independent testing bodies. A key component of these inspections is the sampling and laboratory analysis of the compost. The test results are published on our website to ensure the greatest possible transparency. The analysis also examines the compost for contaminants (see ‘Table 3: Test results for dietary fibre’). Compliance with the Austrian Compost Ordinance is certified in Chapter ‘4. Compost Assessment’ through classification into Quality Class A+ (our organic compost Bio Kompost) or Quality Class A (conventional compost). Plastics in particular are extremely difficult to separate due to their material properties (e.g. low weight, low resistance to mechanical stress, non-magnetic…). Even more intensive technical processing of our compost to separate the last, very isolated plastic particles (according to compost test results < 0.2%) is by no means proportionate to the associated environmental impacts (e.g. CO2 emissions from the additional energy consumption). As a company committed to environmental sustainability, we could not condone this. Furthermore, to our knowledge, there is currently no process that allows for the complete separation of plastics. We therefore ask that any plastic parts found be removed by hand. We would also be delighted to invite you to visit our premises in person to see for yourself. Once a year (on 1 May), as part of our open day, we even offer free guided tours with our CEO Gerald Dunst, during which all our work processes are demonstrated and explained. As a company dedicated to the sensible recycling and recovery of biogenic waste on a daily basis, we take our responsibility towards nature very seriously!

A white fungal network in your soil is nothing to worry about; in fact, quite the opposite: all our soils thrive on an extremely diverse microbial ecosystem. Decomposing fungi are an important part of this system. They use the nitrogen from the horn shavings to produce their own fungal protein. The bound nitrogen is later mineralised, making it directly available to plants.

It depends. If no other material is available, you can use grass clippings or straw. Whilst both materials do provide some protection for the soil, they also have a number of drawbacks. Grass clippings are usually still very damp and compact, and this often simply leads to rotting, especially if they are applied in a very thick layer. They should therefore be left to dry out before being spread. Furthermore, there is an increased risk of weeds sprouting from the grass clippings and spreading in the bed. Straw has a rather coarse texture and often floats to the surface when watered. Both materials also provide only a limited amount of nutrients, and only for a short time. Ideally, our organic fibre Bio Faser should be used for mulching. It is structurally stable, is not blown away by the wind and supplies the soil with nutrients.

Our soil activator Bodenaktivator kick-starts humus formation in the soil. With consistent use over several years, you can transform your own soil into Terra Preta. However, this only works for outdoor use in beds with direct soil contact, not (!) for repeatedly refreshing potting soil. The existing soil biology, including macro-organisms, is essential; otherwise, nutrients and structure will eventually be depleted due to the limited space. Mulching, e.g. with our organic fibre Bio Faser, is of course also essential for this application. (See also Why should I mulch every soil?)

Under no circumstances should the ‘layering method’ be used. (This is only appropriate in hugelkultur.) This method of filling increases the risk of anaerobic processes occurring. Rot may develop due to the pressure of the soil on the filling material and the resulting lack of air. Anaerobic processes lead to a loss of humus, and the raised bed will need to be topped up frequently. It is better to fill the majority of the raised bed with loamy sand, old/existing garden soil (topsoil) or our organic raised bed soil Bio Hochbeeterde and then top up the top 30 cm with a highly fertile soil such as our Terra Preta Schwarzerde. Afterwards, you should always ensure there is a layer of organic mulch, e.g. made from our organic fibre Bio Faser, to keep the soil in your raised bed healthy (see also Why should I mulch every soil?). For information on building a raised bed, see also: Filling a raised bed correctly: Why the layering method is harmful (and how to do it better).

Our organic raised bed soil Bio Hochbeeterde consists of equal parts of our organic compost Bio Kompost and loamy sand (bagged products also contain expanded clay granules, vermiculite, wood fibre and horn shavings). It is extremely rich in humus and nutrients and reliably delivers high yields of healthy vegetables for several years. Unlike our Terra Preta Schwarzerde, which, when used as ‘Terra Preta’ in the appropriate layer thickness (20–30 cm) in combination with a layer of organic mulch, never needs to be re-fertilised (see also Why is your Terra Preta Schwarzerde permanently fertile?), when using our Bio Hochbeeterde, nutrients must be replenished over time, e.g. in the form of compost and/or horn shavings, as it lacks biochar to act as a nutrient store. We also recommend applying an organic mulch layer, e.g. made from our Organic Fibre Bio Faser, when using our Bio Hochbeeterde. This promotes microbial activity and prolongs the soil’s fertility.