Sampling considerations and field evaluations for soil quality assessment

Authors: Liebig, Mark; CHESSMAN, D. - Natural Resources Conservation Service (NRCS, USDA); Halvorson, Jonathan; LUCIANO, ROBERTO - Natural Resources Conservation Service (NRCS, USDA)

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 6/1/2021
Publication Date: 8/30/2021
Citation: Liebig, M.A., Chessman, D., Halvorson, J.J., Luciano, R. 2021. Chapter 2: Sampling considerations and field evaluations for soil quality assessment. In: D.L. Karlen, D.E. Stott, and M.M. Mikha (eds). Soil Health: Volume 2: Laboratory Methods of Soil Health Analysis, Madison, WI: Soil Science Society of America (SSSA), & Wiley International. p. 17-37.

Interpretive Summary: Approaches to assess soil quality vary with the goals of the evaluator. Goals may range from a qualitative understanding of a soil’s near-surface condition at single point in time, to a detailed analytical characterization of a suite of soil properties across a landscape as part of an evaluation of long-term soil change. The diversity of goals and possible approaches to soil quality assessment requires evaluators to consider tradeoffs inherent to selected assessment approaches. Whether a land manager, consultant, conservationist, or scientist, each evaluator will need to balance the desire for useful information about a soil’s status with the investment of time and resources to obtain that information. To facilitate the efficient selection of assessment approaches, guidelines were compiled for soil sampling and field evaluations for soil quality assessment. Multiple approaches exist, underscoring the importance of tailoring an approach that considers site characteristics, project objectives and resources, and evaluator expertise.

Technical Abstract: Soil quality assessments should provide useful insights into the status of soil function, and such insights should be transferable to land managers to guide management decisions. However, the value of assessment outcomes is often linked to decisions made by evaluators regarding sampling location, time, frequency, and method. Accordingly, evaluators need to be aware of tradeoffs associated with different assessment approaches. To facilitate proper selection of an assessment approach, guidelines were compiled for soil sampling and field evaluations for soil quality assessment. Sampling considerations include sources of error (e.g., selection, processing, measurement, and interpretation errors), site characterization, sampling design (e.g., judgement, simple random, stratified random, and systematic sampling designs), composite sampling, sampling depth, and timing and frequency of sampling. Pragmatic considerations concerning soil sample collection, processing, and archiving require careful review prior to initiating an assessment. Field evaluations of soil quality are a useful complement to traditional soil sampling and analyses, and may include general field observations, visual soil evaluations, test kits, and sensor-based measurements. Collectively, the broad portfolio of soil quality assessment approaches underscores the importance of tailoring an approach that considers site attributes, project resources, intended use of data, and evaluator expertise.