Soil quality under different land uses in a subarctic environment in Alaska

As the demand for food, feed, fiber, and, most recently, bio-energy increases, more land may be converted from native conditions for arable uses. Our objective was to evaluate soil quality under native forest, arable land being used for continuous barley (Hordeum valgare L.) production and land that had been tilled and subsequently enrolled in the Conservation Reserve Program (CRP) for at least 18 years. Several physical, chemical, and biological soil quality indicators were measured and a soil deterioration index (DI) was calculated using forest soil as the reference. Results indicated that most organic matter under forest resided on soil surface and was not mixed with mineral soil due to lack of activities by large soil fauna (e.g., earthworms). Soil samples from disturbed areas had a higher organic matter content, which caused most soil quality indicators to be considered ‘improved’ and resulted in better DIs for agricultural and CRP land than for forest soils. This study emphasized the importance of choosing an appropriate reference point for soil quality assessments, especially when data representing one or more key soil processes are missing.