CLORPT

CLORPT is a conceptual framework in pedology that identifies five major factors influencing soil formation: Climate, Organisms, Relief, Parent material, and Time. The term originates from Hans Jenny’s 1941 work, which proposed that soil properties arise from interactions among these factors rather than from any single cause.

Climate encompasses long-term patterns of temperature and precipitation that govern rates of weathering, leaching, and organic matter turnover. Organisms include plants, animals, microbes, and soil biota that influence soil structure, nutrient cycling, and organic matter inputs. Relief refers to topography, slope, and landscape position, which affect drainage, erosion, sediment deposition, and microclimate. Parent material is the underlying rock or sediments from which soils develop, determining mineralogy, texture, and the starting chemical composition. Time represents the duration of soil-forming processes, allowing horizon differentiation and cumulative effects to accumulate.

In practice, CLORPT is a heuristic tool: its factors are interrelated and can vary in importance across landscapes and scales. The model helps explain why soils with similar climates may differ due to biology or parent material, and why soils in different climates may converge under certain conditions. Limitations include the simplification of complex processes and the influence of human activities such as land use and management.

The CLORPT framework remains central in soil science, guiding soil surveys, interpretation of soil variability, and land management decisions by highlighting the drivers of pedogenesis.