Potential Observation Reduction for Characterizing a Suite of Soil Surface Properties in Native Prairies in the Midsouthern United States

Because of the potential economic gain from carbon (C) credits associated with implementing certain soil conservation practices, the number of grassland restorations will likely increase in the future as a result of their soil C sequestration potential. However, soil characterizations and accurate assessments of soil C sequestration in native prairies will be central to understanding the potential ecological target for grassland restorations and for establishing reasonable C credits that can be accrued from expected soil C sequestration in grassland restorations. Therefore, the objective of this Study was to evaluate the degree of observation reduction that could potentially be made while maintaining similar statistical ability to detect differences among site-soil mapping unit combinations for a suite of soil properties determined using a transect approach to characterize near-surface soil properties in native tallgrass prairies. A reduction from five to four observations per prairie site-soil mapping unit combination (i.e., per transect) did not decrease the number of significant differences that could be detected among treatment combinations for a suite of near-surface soil properties and maintained the ability to detect differences in soil organic matter and total C in two contrasting physiographic and climatic regions of the midsouthern United States. A reduction from five to three or fewer observations per transect resulted in a greater than 25% decrease in the number of soil properties, including soil organic matter and/or total C, for which significant differences among prairie site-soil mapping unit combinations could be detected when differences were known to be present. Reducing the number of observations or samples collected along a transect without sacrificing the ability to detect significant differences among prairie site-soil mapping unit combinations provides flexibility to save sampling time and cost of sample analyses or to sample additional sites, if available, to improve data sets for statistical evaluations.