Mullastruktuur

Mullastruktuur (Estonian for soil structure) refers to the organization of soil particles into aggregates and the resulting network of pore spaces. It governs how water, air, and roots move through the soil and is shaped by physical, chemical, and biological processes. A soil with well-developed structure typically shows good aggregation, stable pores, and resistance to crusting, while poorly structured soil may compact, pond water, or restrict root growth.

Common structural types described in soil science include granular, blocky, prismatic, and platy forms, as well as structureless or single-grained states. Granular structure is crumb-like and common in fertile topsoils, promoting infiltration and root penetration. Blocky structures form cube- or cone-shaped aggregates, often in the subsoil. Prismatic structures feature vertical columns and can influence drainage direction, while platy structures consist of flat plates and may hinder vertical movement. The stability of aggregates under wetting and drying is a key indicator of structural quality.

Mullastruktuur develops from interactions among soil texture, organic matter content, biotic activity (such as earthworms and mycorrhizal networks), moisture regime, and management practices. Disturbance from heavy machinery, over-tillage, or compaction can degrade structure, whereas practices like reduced tillage, cover cropping, and addition of organic matter improve aggregation and porosity.

The structure of a soil affects water infiltration and retention, aeration, nutrient availability, root growth, erosion resistance, and carbon storage. It is a central aspect of soil health assessments, land management planning, and agricultural productivity.