Can Truffles be Cultivated?

Short answer … Yes.

Long answer … it’s complicated.

While the cultivation of, for example, shiitake or oyster mushroom are well established the truffle, cultivation is on its way. That was at least my first impression when I started my research. But I was taught better.

The leading cause of that, I reasoned, is the fact that shiitake and oyster mushrooms are so-called saprophytes while truffles are ectomycorrhizal mushrooms.

If you are new to mushrooms, and you want to learn more about the difference between saprophytic and ectomycorrhizal mushrooms, then you will find more information in my article “What are mushrooms?”

While the saprophytic fungi need dead organic matter to grow, the ectomycorrhizal mushrooms need a living plant to survive. And here comes the tricky part.

To get the conditions for the saprophytic mushrooms correct, it’s relatively easy. But to achieve the same for an ectomycorrhizal is a challenge. But and that is the good news: It can be achieved!

In the following article, I will give you a brief introduction about the main conditions for the truffle mushroom to thrive.

CULTIVATION

As mentioned in the beginning, truffles are mycorrhizal fungi. They, therefore, need a host tree from which they get their nutrients[1]. This relationship has to be well established. If done correctly, then after 7 to 15 years, the first truffles will appear.

It, therefore, takes time and especially patience. But a 14-year-old plantation can produce between 50 kg/ha and 100kg/ha. On experimental orchards, up to 200kg/ha could be achieved.

The Net Present Value ranges from 19,424 €/ha to 66,972 €/ha. Which is equal to 1.94 €/m² to 6.70 €/m². At an annual net cash flow of 2,691 €/ha over 35 years[2].

Well, known truffles are the Tuber mesentericum, Tuber melanosporum, and Tuber brumale.

If we look at the worldwide production, we recognize a continues to decline since the twentieth century. The production dropped, for example, in France from 1,000 to 50 tons[3].

The cultivation itself is done on orchards. With Spain, the worldwide leader[4]. With Spain as the leader, we already get an idea about the conditions the orchard needs. Besides Spain, there are a lot more countries in which truffles are nowadays produced.

Locations[5]

Spain
France
Australia
Italy
Canada
USA
Israel
Chile
Morocco
New Zealand

Weather conditions

If we analyze these regions, we found that truffles can be cultivated within the following geographical conditions[6] and, therefore, climate conditions[7].

Up to 1,800m
South-facing slopes
485 to 1,500 mm/year (min. 72 mm)
Mild springs, relatively warm summer, autumns without early frost
-25°C to 43°C can be handled
But max. 5 days below -10°C

Even though truffles can handle a wide range of temperatures, it is recommended that the annual temperature stays between 8.6 and 14.8°C (Table 1).

Table 1: Recommended temperature range (Fischer 2017)

Soil conditions

After going through several papers, I found the following parameters for the soil conditions.

Stoniness (good drainage)
But is the soil having no nutrient than the soil isn’t favorable
pH 7.5 – 8.5
Calcium is essential
Texture: loam, sandy loam, sandy clay loam
But heavy clay soils (> 46% clay) are not favorable
Organic matter 0.8% to 37% (recommended 1.5% to 8%)
C/N 8 to 15
NPK: Significant concentrations of nitrogen, phosphorus, and potassium in the soil are not necessary for truffle production.
Nitrogen: 0.1% – 0.3%
Phosphorus: 0.1% – 0.3%
Potassium: 0.01% – 0.03%

To sum these, finding up, the following figure 1 provides us a good insight into the necessary soil texture. This triangle is formed by the three compounds clay, sand, and silt. With the best soil composition described as loam and clay loam (Figure 1, grey area).

Figure 1: Tuber melanosporum soil texture triangle[8]

Biological Conditions

To get a better understanding of the soil conditions which are needed for the cultivation of truffles, we can look at areas that are typically used for orchards. These are sites where cereals, forage crops, and legumes have previously been cultivated. Also, vineyards and fruit orchards are considered suitable[9].

IRRIGATION

In the early stage, seedlings should be irrigated with 3 to 4 liters every two to three weeks[10]. Later on, during the production phase, the irrigation should be between 25 liters/m² and 60 liters/m²[11].

But the irrigation should be in sync with the regional rainfall (Figure 2) to avoid over-irrigation and especially to the host tree.

Figure 2: Mean values of summer rainfall (mm) and winter rainfall (mm) from plantations in countries that have a history of Tuber melanosporum natural population (Old) and those that do not (New)[12]

Besides these conditions, one scientific paper mentioned that heating the soil before plantations could support the symbiont tree by inhibiting the native fungi[13].

INDICATORS / PREDICTORS of TRUFFLES

In one of the papers, I found an interesting section about potential indicators to find truffles.

The author wrote that “orchids play a special role in truffle ecology. [Because] […] analyses have shown that Tuber species form mycorrhizas with orchids, and simultaneously form ectomycorrhizas with the roots of the neighboring tree[14]”.

HOST TREES[15]

As mentioned in the beginning truffles are mycorrhizal fungi and they, therefore, need a host. The host plant species should be chosen according to the plantation site.

Tuber melanosproum can form mycorrhizas with evergreen holm oak, Quercus ilex sp. ilex, Q. ilex sp. ballota), semi-deciduous and deciduous oak trees, portuguese oak, and downy oak (Q. faginea, Q. pubescens), Kermes oak (Q. coccifera), hazelnut trees (Corylus avellana), rockrose (Cistus incanus), several pine species (Pinus pinea, P. halepensis, P. nigra), European hop hornbeam (Ostrya carpinifolia), European hornbeam or ironwood (Carpinus betulus), and linden trees (Tilia sp.) (Palenzona 1969; Manna 1992; Bencivenga et al. 1995).