Laboratory Soil Handling Affects CO2 Respiration, Amino-N and Water Stable Aggregate Results

William F Brinton

doi:10.19080/artoaj.2020.22.556262

Abstract

Laboratory analysis of soil traits associated with soil quality or soil health has gained popularity very recently reflecting a trend begun over a half-century ago scrutinizing farming systems for potentially deleterious soil effects. This renewed focus has brought into the forefront concerns about how laboratory soil handling may influence the observed traits. We find evidence in the literature that many but not all these concerns were addressed decades ago before the topic became of widespread interest but also before the soil testing industry modernized to high-throughput methods of soil homogenization not designed for soil quality investigations. Consequently, we find it necessary to retrace some steps in order to better characterize artifacts that may hamper objective evaluation of soil responses associated with soil health before conclusions of management effects of farming systems are drawn.

Highlights

Work established that soil analyses oriented to biological traits could enhance the capability to distinguish short- and long-term management effects on soils due to differing farming systems [1]
This coincided with methodological developments for microbial biomass via CO2 respiration [4] and efforts including microbial respiration and enzyme activity to derive a “soil microbial index” [5]
A shift in some research focus to alternative agriculture, defined as farming systems employing non-conventional methods, resulted in new recommendations for soil biological measurements [7] and development of a “soil quality index” [8]. Deployment of such methods to evaluate farming system effects led to incorporating enzymes, earthworm counts and soil microbial respiration as routine analytes [9]

Summary

Introduction

Work established that soil analyses oriented to biological traits could enhance the capability to distinguish short- and long-term management effects on soils due to differing farming systems [1] Around this time, biological indicators including CO2 evolution were proposed as criteria for “soil biological activity” [2] and “healthy soil” [3]. A shift in some research focus to alternative agriculture, defined as farming systems employing non-conventional methods, resulted in new recommendations for soil biological measurements [7] and development of a “soil quality index” [8] Deployment of such methods to evaluate farming system effects led to incorporating enzymes, earthworm counts and soil microbial respiration as routine analytes [9]. A recent meta-analysis of 149 paired farm comparisons employing biological soil tests including enzymes, basal CO2 respiration and soil biomass, based on CO2 respiration indicated that most were effective to reliably distinguish soil impacts in organic farming compared to conventional systems [10]

Methods

Results

Conclusion