Several key techniques in calculating gross N transformation rates by ¹⁵N dilution methods were reviewed in this paper. Such techniques include methods of applying ¹⁵N to soil, amount, enrichment and types of ¹⁵N addition, and initial sampling time. Only when these techniques were applied reasonably under particular conditions, ¹⁵N dilution methods could be successfully to quantify gross N transformation rates and to understand the fundamental processes that regulate individual microbial N pathways.