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United States Department of Agriculture

Agricultural Research Service

Title: Soil Biological Characteristics of Contrasting Cropping Systems in the Great Plains: Summary of Preliminary Findings

Authors
item Liebig, Mark
item Carpenter-Boggs, L - WASH ST UNIV-PULLMAN,WA
item Johnson, Jane
item Wright, Sara
item Barbour, Nancy

Submitted to: Proceedings from Dynamic Cropping Systems: Prinicples, Processes, and Challenges
Publication Type: Proceedings
Publication Acceptance Date: May 22, 2003
Publication Date: August 4, 2003
Citation: LIEBIG, M.A., CARPENTER-BOGGS, L., JOHNSON, J.M., WRIGHT, S.E., BARBOUR, N.W. SOIL BIOLOGICAL CHARACTERISTICS OF CONTRASTING CROPPING SYSTEMS IN THE GREAT PLAINS: SUMMARY OF PRELIMINARY FINDINGS. In: Proceedings from Dynamic Cropping Systems: Principles, Processes, and Challenges. Hanson, J.D. and J.M. Krupinsky (eds.). August 5-7, 2003, Bismarck, ND. 2003. p. 210-214.

Interpretive Summary: Understanding biological contributions to soil function is important when assessing soil quality. A multi-location study in the Great Plains was conducted from 1999 to 2002 to evaluate the effect of contrasting cropping systems on soil biological properties over time. The cropping systems (alternative and conventional) differed in the type or frequency of tillage, frequency of cropping, and/or crop rotation diversity. Alternative cropping systems - characterized by continuous cropping, diverse crop sequences, and/or reduced tillage - had higher levels of microbial biomass and potentially mineralizable N at most locations, indicating these systems had a greater capacity to supply N to plants over the growing season. Alternative cropping systems at four locations also had greater wet aggregate stability than conventional cropping systems, thereby conferring improved air and water movement through the soil in these systems. The composition of the soil microbial community was found to be most diverse in the surface 7.5 cm of soil across all locations. Preliminary findings from this study indicate there is merit in pursuing alternative management practices to enhance biological indicators of soil quality.

Technical Abstract: Understanding biological contributions to soil function is important when assessing soil quality. A multi-location study in the Great Plains was conducted from 1999 to 2002 to evaluate cropping system effects on soil quality over time. Several soil biological parameters considered to be indicators of soil quality were assessed in contrasting cropping systems (conventional and alternative) at depths of 0 to 2.5, 0 to 7.5, 7.5 to 15, and 15 to 30 cm. The cropping systems, which were part of eight long-term experiments, differed in management intensity with respect to type or frequency of tillage, cropping intensity, and/or crop rotation diversity. Alternative cropping systems - characterized by continuous cropping, diverse crop sequences, and/or reduced tillage - enhanced levels of microbial biomass and potentially mineralizable N at 0 to 7.5 cm, indicating a greater capacity of the soil to supply plant-available N in these systems. Alternative cropping systems at four locations possessed greater wet aggregate stability than conventional cropping systems in the surface 2.5 cm. A weak cropping system effect on total glomalin, however, suggested a different glomalin fraction might be contributing to trends in aggregate stability between cropping systems. Soil depth was the primary determinant of fatty acid methyl ester (FAME) profile across locations, with extracted FAME amounts, richness, and diversity greatest at 0 to 7.5 cm. Preliminary findings from this evaluation indicate there is merit in pursuing alternative management practices to enhance biological indicators of soil quality.

Last Modified: 4/15/2014