New organic substrate

The wood shavings from sawmills can be used to produce an organic substrate for use in intensive crop growth in containers. Moreover, this substrate has the advantage that it can be recycled and is more economic than other, imported ones such as peat or coconut fibre.

These are the findings of researchers at the Public University of Navarre who, jointly with the Aralur company in Ziordia (Navarre), have developed this substrate material. The product has already been patented and marketed.

These types of substrates are used in intensive farming that need containers for their development, basically for greenhouse crops.

When plants are grown in small containers, the limiting factor is the oxygen that can reach the roots; thereby, a substrate much more porous than earth is needed. Normal soil encloses some 50% of air in its interior, while this substrate encloses 90% of air and 10% of solid material. This is why these substrates accelerate the growth processes of the plant and provide much better results.

Productive, economic and recyclable

In concrete, the product developed has the commercial name of "FIBRALUR" and is made from pine wood shavings which have been defibred by means of an industrial process. The resulting material has proved to be efficacious in growing mushrooms and other hydroponic crops – nursery crops grown outside the soil – and, to a lesser extent, with vegetable and forest nurseries. It is a substrate that can compete with those in the market, especially those used for mushrooms and hydroponic crops, as a single substrate, while for the nursery crops it should be mixed with peat.

Peat is the prime substrate at a worldwide level as it provides great technical performance but, on the other hand, it is mostly imported from colder regions in the North of Europe (Finland, Sweden, Norway, etc.). This is why the advantage of the product developed by the Public University of Navarre research team and the Aralur company is that it is a home-grown product that is produced in situ and, thereby, is much more economic.

Moreover, hydroponic production involves the use of inorganic substrates such as Perlite or rockwool and which, once used, have to be selectively removed from tips and rubbish dumps. On the other hand, wood fibre, as with peat, are recyclable organic substrates, i.e. after its first use it can be reintroduced into the soil, as if it were manure being applied to the crop field.

Defibreing the wood

To obtain the substrate the same machinery is used for defibreing wood to make paper but, in this case, the fibres obtained are much thicker and longer. Wood fibre for papermaking goes through two or three defibreing processes while FIBRALUR substrate is the result of a single defibration.

During this defibration process the bark of the pine is subjected to a washing in water at a temperature of 90-115 ºC, the resulting cellulose being practically pure, free of phytotoxic products and ready to be used in the growing of agricultural crops.

Source : Elhuyar Fundazioa