I'd like to study the change in nutrients throughout the soil column after application of biochar in acid soil. How should I collect and prepare soil sample for the study?
Paul's statement is the most important question to answer first. Our paper linked here compares movement in undisturbed vs. packed columns - it will likely be markedly different.
Related: this paper shows the challenge of undisturbed columns: heterogeneity between columns in terms of flowpaths present and resulting effects on column hydrology: