Review of Soil Organic Matter Fractions Under Different Cropping Systems in Temperate Climates: A Meta-Analysis.

An improved understanding of the influences of management practices on soil properties and associated soil function is needed to efficiently implement national conservation programs. The objectives of this study are to assess the relationships between various cropping systems and associated management practices with soil quality attributes. Data published in the scientific literature from studies that evaluated the effect of soil management on soil organic matter and other dynamic properties were collected and analyzed using techniques developed for meta-analysis. Variables considered were selected to represent soil functions or ‘micro concerns’ presently estimated within the Natural Resource Conservation Service’s Conservation Measurement Tool (CMT) which is used to determine eligibility for the Conservation Stewardship Program. This approach will allow us to summarize data from multiple research sites and draw more robust conclusions about management by site interactions.  Moreover, statistically-based estimates of practice performance can be compared against rankings derived from the CMT and used to determine if and how ranking tools can be regionalized.  Preliminary analyses comparing organic matter concentrations in soils under conventional management with those in soils under alternative management (minimum tillage, non tillage, and organic) suggest an average increase of 10% soil organic carbon in surface depths. Further analysis will investigate the effect of specific agricultural practices like rotation length, crop species within rotation, use of cover crops, and N fertility sources as these are farm-based practices that influence soil functioning.