Soil tilth describes the friability and physical quality of a soil for crop growth. Soil tilth is an old concept yet its direct quantification remains difficult. Tilth is characterized by measuring soil properties related to soil aggregates, pore structure, mechanical resistance and organic matter, or in the field using methods such as visual evaluation of soil structure. Soil tilth is positively influenced by management that increase soil organic matter content, and negatively influenced by soil compaction. Tillage to produce tilth can have positive or negative effects over time, the latter prompting shifts to reduced or no tillage.