Soil Aggregate Stability in Four Different Climates.

Aggregate stability is considered an important indicator of soil quality. Moreover, it has a strong influence on many processes in soil such as carbon storage, infiltration and aeration, root development, and resilience to water erosion. Aggregate breakdown is the first step for soil crusting and sealing. Therefore, the presence of stable aggregates in the soil is crucial to maintain productivity. Different approaches to measure soil aggregate stability has been used, however, few attention has been put to measure it with a standard method in different soil types. Thus, the objective of this study was to build a novel standardized database of soil aggregate stability based on physical-chemical analysis and determination of the percentage of water stable aggregates using wet sieving apparatus. With this purpose, 107 soil samples from Northern to Southern Chile were collected at 0-15 cm depth in four different climates (arid, semi-arid, moist and cold steppe), including forest and cultivated soils. The organic matter content ranged from 1% to 21% with clay to loamy sand textures. Our results showed a high correlation between aggregate stability and pH. In addition, a positive gradient of aggregate stability from North to South was found, with aggregate stability from 15% to 97%. This paper is the first attempt to evaluate the aggregate stability along a climatic gradient in Chile. It provides a better understanding on the factors controlling soil aggregate stability, that could be used for soil conservation and carbon sequestration.