Back D. L. Karlen
National Soil Tilth Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Ames, Iowa, USA
Full Paper (PDF File: 256KB)
Abstract
Developing the concept of soil quality may help identify the soil and crop
management practices required for environmentally, socially, and economically
sustainable agriculture. Objectives of this paper are (1) to review current
efforts to define soil quality, (2) to discuss factors and processes which
influence soil quality, (3) to identify, soil and crop management practices
that affect processes influencing soil quality, and (4) to demonstrate
a method for evaluating soil quality. A common focus among all proposed
soil quality definitions is that the soil must reflect its ability to "function"
in numerous ways at the present time and in the future. Soil and crop management
practices that add or maintain soil carbon appear to be among the most
important for restoring, maintaining, or improving soil quality. This includes
utilizing reduced tillage, producing green manures or cover crops where
climate and water resources will support the practice, applying supplemental
animal or poultry manures or composted materials when available, and enhancing
biological diversity to facilitate nutrient cycling and maintain soil structure.
The soil quality assessment method that has been developed does not provide
a definitive answer with regard to the measurements or specific functions
which should be included in a soil quality index, but it uses specific
measurements that describe soil functions and it is dynamic. Therefore,
research focusing on the development of a soil quality index is justified
and should be continued.