Reference Ecological Unit: A Land Classification Unit for Comparative
Soil Studies
Abstract
There is a growing consensus on a need for comparing the cropland with a
reference state or native land in a prime soil health state to determine
soil health management goals in croplands. However, the complex soil
heterogeneity and climate variations make soil health potential variable
and confound the land-use and management practices while comparing soils
from different sites. Identifying a discrete landmass unit where all
soils have similar health potential will be instrumental in conducting
meaningful comparative studies. This methodological paper proposes and
discusses a land unit, Reference Ecological Unit (REU), that accounts
for soil and climate variabilities and covers the area with similar soil
health potential. The REU is developed for one Major Land Resource Area
in Nebraska based on the USDA-NRCS hierarchical land classification
system. A true difference in soil health for different land use and
agronomic management practices such as no-till and cover crops can be
determined by comparing sites within an individual REU. Evaluation of
management effects on soil health indicators in an REU will adequately
illustrate the beneficial impact of such practices without being
confounded by agroecological variations.