After choosing a site for your truffle plantation, you should have the soil tested to measure its natural pH, buffering capacity, organic matter content and the availability of plant nutrients. The suitable soil pH range is between 7.5 and 8.3, but 7.9 is considered ideal. If your soil pH is below this level, you will need to add lime to raise the pH. Raising the pH can take several years with annual lime applications, but the trees can be planted before the pH reaches the ideal level. However, if the soil pH is low then other fungi living naturally in that soil are probably better adapted to low pH conditions and the faster you get your pH into the ideal range the less likely other fungi are to become established on the roots of your truffle trees. The best approach would be to raise the pH all the way to 7.9 before the trees are planted to give potential competitors as little opportunity as possible to exploit non-ideal conditions, but few farmers are willing to wait that long before planting.
The amount of lime required to raise the pH varies with the starting pH, the soil texture and buffering capacity and the type of lime that you use. The ideal pH is way above levels ideal for maximizing soil fertility and approaches the level where most plants begin to suffer from various nutrient deficiencies. Consequently, agricultural specialists will have a difficult time predicting the amount of lime required to raise the pH since they typically have no experience with raising pH to these levels. The task for the truffle farmer is to add lime incrementally with continued pH testing until the ideal pH is reached. Unfortunately, lime can take two or more years to have its full effect on soil pH and it is often difficult to incorporate additional lime once the trees are planted. The best approach is therefore to apply the majority of the lime in a single application prior to planting the trees, followed by annual pH testing and incremental surface applications until the pH reaches 7.9. Once the ideal pH is reached it will need to be maintained with supplemental lime applications as necessary since rain water tends to leach calcium from the soil and reduce pH over time.
It is also important to correct serious nutrient deficiencies and imbalances prior to planting. Truffles often do better in relatively low productivity soils, but they use all of the same nutrients required by their host trees and will suffer if those nutrients are seriously deficient or made unavailable by imbalances. However, it is important not to overdo it with fertilizers. Generous fertilization will benefit the host tree, but, at some point, the truffles are unable to take advantage of excess nutrition and other fungi that are able to respond to higher soil fertility may gain the competitive advantage.