Are researchers following best storage practices for measuring soil biochemical properties?

Abstract. It is widely accepted that the measurement of organic and inorganic forms of carbon (C) and nitrogen (N) in soils should be performed on fresh extracts taken from fresh soil samples. However, this is often not possible, and it is common practice to store samples (soils and/or extracts), despite a lack of guidance on best practice. Here, we demonstrate how differences in soil and/or soil extract storage can compromise sample integrity for the quantification of soil dissolved organic C and N, extractable inorganic nitrogen (NH₄⁺ and NO₃⁻), and microbial biomass C and N. We discuss and provide the appropriate tools that will ensure researchers consider best storage practice methods when designing and organising ecological research involving assessments of soil properties related to C and N cycling. We encourage researchers to use standardised methods where possible and to report their storage treatment (i.e. temperature, duration) when publishing findings on aspects of soil and ecosystem functioning. In the absence of published storage recommendations for a given soil type, we encourage researchers to conduct a pilot study and publish their findings.