Soil surface rock fragments

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.

Soil and plant testing for truffle cultivation in North America by Shannon M. Berch and Mark Coleman

Purpose of this document
Part 1: Soil testing for truffle cultivation
Part 2: Plant nutrition tests for truffle cultivation
Part 3: Interpretation of soil and plant tests
Appendix 1: Calculating plant leaf nutrient concentrations in proportion to N concentration
Appendix 2: Units and conversions back to a standard with which recommendations are made
Literature references