2 concept questions

Calculating bulk density core vs excavation method

In agricultural soils, bulk density can commonly be determined using the core method. However in rocky forest soils (i.e. coarse fragments > 25%), the excavation method is often used. The excavation method involves digging out a small hole, then oven drying (at 105°C) and weighing the excavated soil. The volume of the excavation is determined by lining the hole with plastic film and filling it completely with a measured volume of water (or sand, or silicon beads). Coarse fragments (diameter > 2 mm) are sieved out and bulk density is calculated as the mass of dry, coarse fragment-free soil per volume of the excavated soil, where volume is also calculated on a coarse fragment-free basis. Full details on this method are online at https://labmodules.soilweb.ca/soil-compaction-bulk-density/