establishing a truffle orchard
Currently enough is known to provide a prospective farmer with sufficient comfort to reduce and manage the risks involved in establishing a truffle orchard. Before deciding on a specific farm where an orchard wants to be established it is therefore important to verify whether the target farm falls within the known parameters for successful truffle production related to climate, soil composition and competing fungi.
The basic guidelines for selecting a farm should therefore not be taken lightly and Mosbec Truffle Farms assists prospective farmers to make an informed decision in this regard.
optimum cultivation of Tuber melanosporum
If the land were used before the following previous crops would be beneficial:
- Grapes and most fruit trees, as they are endomycorhizal (except hazels and walnuts)
If the land was planted with any other crop it is recommended that the soil be rested for several years.
There are however many examples in the USA and Australia where excellent truffle production is achieved in areas that fall outside these climatic parameters.
Hottest month (Feb) average temperature: Not higher than 23.5 Degrees Celsius
Coldest month average temperature: Higher than 1 Degrees Celsius
Note: There are however many examples in the USA and Australia where excellent truffle production is achieved in areas that fall outside these climatic parameters.
Tuber melanosporum fruits best in dry and hot conditions, with well-marked seasons, humid temperate or cold sub humid Mediterranean climate. It thrives in hot and humid springs, dry summers with some storms, no frost at the beginning of autumn, and winters with no long cold periods. Black truffle is harvested in winter and may be damaged by heavy frosts.
Rainfall in South Africa is of no consequence as our rainfall is too low and therefore yearlong irrigation is a must.
Alkaline: pH between 7.5 and 8.4 (if lower than 7.5 pH can be raised by adding lime).
Texture: Loam, Loamy silt, Loamy sand, Clay loam
Before making a choice the following tests need to be conducted on representative soils samples:
pH, electrical conductivity, calcium carbonate equivalent, organic matter, nitrogen, phosphorus, potassium, calcium, magnesium, sodium, C/N ratio, and textures
The preferred ranges are:
- Phosphorus (P): lower than 30 ppm (Olsen)
- Nitrogen (N): between 0.1% and 0.5%
- Potassium (K 2 0): lower than 400 ppm
- Organic matter (M.O.): between 1% and 10%
- Carbon to nitrogen ratio (C/N ratio): between 5 and 15
The results of the tests will be analysed by our Technical Partner who will recommend the selected farm or not.
They prefer to do an on-site inspection of the following before they make a recommendation:
- Signs of soil suffocation or poor drainage
- To check for the presence of carbonates
- Manual inspection of soil texture
If the soil analysis is not optimum as some nutrients are over the thresholds, then planting the following crops can treat the soil and add nutrients and organic material: wheat, oat, barley maize, sorghum, and sunflower.
Maximum elevation is 1800 meters above sea level. A slight slope to assist in drainage is preferable but not necessary.
Soil should be free draining, well aerated, low nutrient levels and relatively free from heavy metal content. Free from pesticides.
Soil should be loose even when dry with good levels of well-decomposed organic matter. The clay content of the soil should be less than 30-35% (depending on rock percentage).
NOTE: It is recommended that we assist potential farmers with site selection to ensure that the best possible site is selected.
A Truffle Farm
The black truffle thrives in open and sunny conditions, that are well drained, aerated and relatively warm. It prefers stable, humus-rich, well-developed organic matter and high biodiversity and activity in its soil. The goal, when creating a truffle orchard, is to optimise these conditions.
Host plant selection
In Europe, the Quercus ilex (Holm or Holly oak) is found to be the preferred host plant and is recommended for South Africa.
In the Southern Hemisphere the following oak species are used with success as host trees:
- Quercus suber (Cork oak)
- Quercus ilex (Holm or Holly oak)
- Quercus Robur (English oak)
- Quercus Prinus (Chestnut oak)
- Quecus Acutissima (Sawtooth oak)
On our own farm of 50 hectares we decided to plant both Quercus suber (Cork oak) and Quercus ilex (Holm or Holly oak).
Literature on these two types of oak trees also indicate that Quercus ilex prefers a soil pH of 7.8 to 8.4 and that Quercus suber prefers a soil pH at 7.5. As most of our suitable farms in South Africa have a pH of lower than 7 we thought it a good idea to make Quercus suber plants also available to our clients to reduce the establishment cost, as adding lime to low pH soil can be expensive. On our own farm we have around 20 hectares with pH lower than 7.5 and 30 hectares with pH around 8. It therefore makes sense to plant both species on our farm.
Preparing the ground
All other trees or vineyards should be removed from the ground.
Compacted ground should be ripped 1 meter deep. Prevent soil from being turned over or being compacted.
Planting of 1-year old inoculated trees can be done in August-September or March.
Density: depending on site-specific climate, but in warm areas an average of 444 trees per hectare 4.5 x 5 meters apart in rows running east west is recommended.
Plant the trees with all the substrate in the plant holder. Substrate is usually well attached to the roots of the trees.
Maintenance of the orchard
Thorough watering of the soil is important.
At least 7 000 cubic meters of water per hectare per annum should be available.
Irrigation schedules are dependent on climatic and rainfall conditions and are best determined by probes to indicate watering needs.
Drip irrigation is not recommended and a micro sprinkler system is preferred.
Soil cultivation, care and pruning
There are several factors in the management of a plantation to achieve good yields that will depend on each farm conditions. Truffles need a soft soil to grow in, so tilling is a common practice to aerate the soil and remove weeds.
Prune, chopping branches, adding truffle spores to the soil and tilling should happen before spring starts at the end of the harvesting season. The window to do all of this depends on how soon the trees will sprout and the moisture content of the soil, but is usually between 2 and 4 weeks after the end of production (mid September in South Africa). Additional tilling in summer is recommended to control weeds, but should be done carefully and very shallow not to damage the mycelium networks that feed the truffles.
No activity to manipulate the soil surface should happen during the fruiting season.
Regular light pruning and shaping the tree in the form of an inverted cone shape is recommended to ensure enough sunlight penetration on the soil.
Damage caused by animals must be prevented. Fencing is recommended.
Mulching of the soil during the first few years is recommended to maintain moisture and regulate soil temperature.
The life span of a truffle plantation is up to 30-40 years of production.
Since the whole DNA of the truffle was sequenced and published, we now have a better knowledge of how truffles feed from the soil and the tree, so due to the latest research from our partners in Spain, specially designed bacterial fertilisers are now available in the market.
Studies on the effect of organic compost also look promising.
Herbicides and pesticides
In general the use of herbicides and pesticides is not recommended. Herbicides affect bacterial community in the soil and bacteria heavily influence truffle aroma, so if we need to use herbicides, they should be biodegradable. BASTA (ammonium glusfosinate) is commonly used in truffle farms.
Lifetime of the truffle plantation
The life span of a truffle plantation is up to 30-40 years of production.
Analysis to control and monitor a truffle plantation
Mycorrhization status analysis is used to determine the level of truffle colonisation in the host tree and its potential to produce, as well as the levels and relative proportions of other contaminating fungi.
Mycelium quantification using molecular analyses (Real Time PCR) of soil samples is used for species identification and compared against a standard curve with known amounts of mycelium.
Our Technical partners offer a full management and analysis service. This service includes level of truffle infection in the roots, recommendation of some substrates to improve fruiting and any management questions are discussed on-line.