Contributions of Soil Archives to Understand Soil and Agroecosystem Change.

Sustaining highly productive and environmentally sound agroecosystems will be a significant challenge over the next several decades given projections for human population growth and global climate change.  Because of these conditions, long-term experiments will play an important role in understanding how agroecosystems affect soil attributes – and, in turn – how changes in soil attributes impact the broader environment.  Documenting management effects on soil attributes requires not only well-managed long-term experiments, but also carefully cataloged soil archives.  Archived soil samples provide an inventory of change in soil attributes over long temporal scales, thereby providing critical insight into agroecosystem sustainability.  More specifically, archived soil samples can be used to address key questions with implications to both agricultural productivity and environmental quality.  Some questions may include: Are soils gaining or losing soil organic matter?  Has the quality of soil organic matter changed over time?  Which plant nutrients are accumulating in soil?  Which are being depleted?  Are soils becoming more acid/alkaline?  Addressing such questions can provide information germane to the development and/or refinement of models for understanding management impacts on key soil functions.  Furthermore, use of ancillary data can provide possible explanations for underlying mechanisms causing soil change.

In this presentation, information from long-term experiments and soil archives will be reviewed using the above questions as a context for understanding management influences on agroecosystem sustainability.  Discussion will focus on sites and archives throughout the US Great Plains, where changes in soil attributes resulting from management can take decades to be expressed.