AEST Natural Resource Specialist Certification Practice Exam

Mollisols are characterized by a thick organic matter layer, which is a defining feature of these fertile soils. This organic matter, typically derived from decomposed plant material, contributes significantly to soil fertility by enhancing nutrient availability and moisture retention. Mollisols are predominantly found in grassland regions and are known for their high agricultural productivity.

The presence of a thick organic matter layer sets Mollisols apart from other soil types and is crucial for supporting healthy plant growth. This characteristic is essential in understanding how Mollisols function as a key natural resource for agriculture and ecosystems.

While cation exchange capacity, base saturation, and mycorrhizal associations are important soil characteristics, they do not define Mollisols in the same way that the organic matter layer does. Mollisols actually tend to have a high cation exchange capacity and base saturation levels above 35%, both of which contribute to their fertility and agricultural value. Mycorrhizal associations, while beneficial for many soil types, are not a distinguishing feature specific to Mollisols. Thus, the thick organic matter layer stands out as the most definitive characteristic of these soils.