Basic statistical analyses of primary relevance to soil organic matter data

Abstract

This study provides an overview of statistical considerations that are commonly encountered in controlled experiments focused on soil organic matter (SOM) and SOM‐related variables. In‐depth treatment of all statistical matters that could arise in such experiments is beyond what could be covered in a single study. Thus, the aim of this contribution is limited to outlining scenarios commonly faced in analyses of SOM‐related data, highlighting the importance of potential issues that might arise in such analyses, and providing general suggestions for dealing with them. The sample scenarios include (i) analysis of microbial biomass C (MBC) data from a laboratory incubation study in a completely randomized design, (ii) analysis of soil organic C (SOC) data from a field experiment in a randomized complete block design, and (iii) an example of analysis of covariance application where sand content is used as a covariate in an SOC‐focused field experiment. Full SAS and R codes shown in Appendices SAS and R for the illustration examples used through the study are intended to provide the reader with a starting point for performing suggested analyses. SAS 9.4 and R version 4.3.1 were used. The reader is encouraged to review specific statistical texts and publications on detailed descriptions of the procedures. For more complex research questions and designs, the reader should consult their favorite statistician and preferably do so during the project planning phase.