Soil Density

A Technical Report from The Bartlett Tree Research Laboratories

Natural soils are a complex network of different-sized particles and aggregations of particles called peds. Organic matter formed from dead roots, decomposed leaves, and branches is the main “cement” that holds the peds together. The spaces between particles and peds allow for the movement of air and water and the growth of roots. An ideal soil is composed of half pore space and half solid. Large pores drain quickly after rain or irrigation so they are usually filled with air. Smaller pores hold water more tightly, so unless there is severe drought, they hold water. Roots grow easily in the pore space, sending root hairs or mycorrhizal strands into the small pores to absorb water and nutrients.