Soil analysis is conducted on the fine fraction, or the soil that passes through a 2 mm sieve. Surface rock fragment class is the mineral material that does not pass through the sieve; it is normally recorded on a volumetric basis. The amount of rock fragments affects soil properties such as the amount of available water and nutrients, the rate at which soil temperature changes, the originating soil parent material, the history of the soil and may dictate management practices. In truffle orchards, rock fragments can cause irregularly shaped truffles and lower truffle quality.
