The black truffle has traditionally been collected in woodlands in the winter. Everything about it has been steeped in mystery, from its formation and growth hidden beneath the ground to its harvesting and commercial and gastronomic aspects, etc. Field practices (in this case, it would be more accurate to say woodland practices) that have given some truffle hunters and growers good results, have been jealously guarded and rarely shared in truffle circles or in technical or scientific forums.
One such practice commonly carried out by truffle hunters is to place one or two handfuls of dead leaves (usually the same leaves of the truffle tree or those from some nearby bush, such as juniper or savin, herbs, or even dried herbaceous plants) into the hole where the truffle was extracted, and then to cover the hole with the same soil that was removed from it. This practice often leads to “a trove of truffles” in the second or third year in these holes.
Various truffles, usually of a more commercial size and form than those found in natural soil, are found in these holes, or “nests”. They can be truffles of any size, but generally they are rounder, less irregular and thus more valuable commercially. This type of truffle fetches a higher price. Two factors are responsible for this more commercial form and size of the truffles: 1) The physical medium (the soil) is much less compacted which makes it easier for the truffle to grow in all directions, thus producing rounder truffles. 2) The evolution of the organic material placed in the hole generates a source of nutrients for the young truffle, producing larger truffles. It is known that the carpophore (young truffle) is autonomous in respect to the symbiont plant from the start of its formation (the myceliar connection with the plant’s roots ceases), and it feeds and grows by absorbing nutrients and water from the immediate surroundings. Thus, physical environment and nutrition favor the formation and growth of the truffles in these holes.
The organic mix introduced into these holes is attacked by soil microorganisms (bacteria, fungi, nematodes, protozoa, etc.) and also in general by all the microfauna in the vicinity (insects, worms, etc.) evolving toward complex structures (hummus) that enormously favors the wealth of life in these spots and these chains of organic remains give way over time to simpler composts that eventually free up nutrients and substances that favor both the tree and the truffles. All of this life probably also stimulates the truffle to reproduce if roots and mycorrhiza coincide in that space, which is often the case with productive woodland trees or in truffle plantations.
Currently, in productive plantations or those near the start of production (when the brûlée is initiated after approximately four to eight years) many truffle growers, with good criteria, open nests in the zone of influence of the brûlée and bury there an organic mixture of variable composition with or without added truffle spores. Once the hole is partially filled with the organic mixture, it is covered up again with its own soil. The production of truffles in these holes can begin after the second or third year. These nests hidden in the soil significantly improve the production of plantations in comparison to what they would produce without them.
Holes (or nests) are dug both inside the brûlée and on its outside edge.
These nests are made from mid-March to mid-June in productive plantations and in plantations about to begin production. They can be dug when the plantation is 4-5 years old. Depending on the seedling’s development and the area of the brûlée, a greater or lesser number of nests will be made. It is common to increase the number of nests as the area of the brûlée grows, and it is even favorable to dig them on the outside edge of the brûlée. The number of nests in each brûlée will depend on the size of the brûlée and often ranges from 4 to 15, depending on the owner’s decision. One or two liters of organic mix is placed in each hole at a depth of 20 to 25 cm..
Introducing the most appropriate mix for an early and sustained truffle production can generate greater profits for the truffle grower. We believe that this cultivation practice will continue to develop and improve with time and will notably increase the production of truffles in plantations. Until now, talk of using fertilizer in truffle patches or in plantations has generated controversy and concern, given the disparity of results in this respect, especially in natural truffle patches. However, in this case, it’s not a question of using a mineral fertilizer, but rather to introduce an organic mix in some specific spots of the brûlée, respecting the mineral composition and balance of life of the soil of the truffle patch, the conditions of which are apparently necessary for the truffle to remain present.
At Cultivos Forestales y Micológicos we began testing mixes of organic substrates for trufficulture nests in 2006.
At Cultivos Forestales y Micológicos we make and commercialize two types of substrates: type A, Matertruf, and type B, Nidotruf, for use in trufficulture.
The type A substrate (Inoculant Substrate) serves as a base to prepare the type B Complete Substrate for Nests. Substrate A contains a mix of different ingredients that favor the development of the root and the formation of new mycorrhizas; it also contains truffle spores. It can also be used to improve the mycorrhizal association of seedlings that don’t form a brûlée due to a poor initial mycorrhizal association.
The type B substrate (Complete Substrate for Nests) is the result of adding organic materials to the type A substrate. This substrate B is used to fill the nests opened in the brûlée.
The type A inoculant substrate for trufficulture
The type A inoculant substrate is placed at the level of the roots of the trees we wish to treat.
We can do this in two ways: 1) We dig holes or small trenches in the area of the zone of influence of the roots (the roots can have a length from the trunk twice the height of the tree) at a depth of 15 to 30 cm, and we place between 100 and 200 cc of substrate at each inoculation spot; the more inoculation spots we create, the greater the probabilities of success. 2) We spread the substrate in a uniform way over the soil of the zone of influence of the roots (100-200 cc per square meter) and then manually or with a mechanical implement we till the soil in order to mix it up to a depth of 15-30 cm.
This substrate A is generally used to re-inoculate or reinforce trees in truffle plantations. If they are trees or seedlings of a forest, etc., we must evaluate the type of soil, climate, particular location of the seedling to be treated, etc.; definitively, we must know the environmental demands (soil, climate, etc.) of the truffle we wish to inoculate. Among the inocula for truffles we offer, the black truffle (Tuber melanosporum) is the most demanding, while the summer truffle allows a greater variety of soil types and environmental conditions.
The type B complete substrate for holes/nests for trufficulture
The type B substrate is used for holes or nests in productive truffle plantations or those near the start of production. It contains the same ingredients as the type A inoculant substrate along with some additional organic materials (vegetal remains, earthworm humus, leonardite, etc.) in a 1:4 proportion. It is a balanced mix designed to favor the formation of truffles in the spots where the mix is placed, maintaining a small “oasis” for the primordia formed in May-June, to improve their possibilities of surviving the dry summer period and to favor their nutrition and fattening at the end of summer and in the autumn. The composition of the mix means it doesn’t dry easily and favors re-hydration after rains or irrigation.
To use it, holes are dug in the zone of the roots’ influence or the brûlée, even on the outside edge of the brûlée, and then one or two liters of the mix are placed in each hole and then covered with the same earth. If everything develops normally, truffles will appear in some holes/nests the second year and more frequently after the second year.