Understanding the variables that affect the anaerobic potentially mineralizable N (PMN an) test should lead to a standard procedure of sample collection and incubation length, improving PMN an as a tool in corn (Zea mays L.) N management. We evaluated the effect of soil sample timing (preplant and V5 corn development stage [V5]), N fertilization (0 and 180 kg ha −1) and incubation length (7, 14, and 28 d) on PMN an (0-30 cm) across a range of soil properties and weather conditions. Soil sample timing, N fertilization, and incubation length affected PMN an differently based on soil and weather conditions. Preplant vs. V5 PMN an tended to be greater at sites that received < 183 mm of precipitation or < 359 growing degree-days (GDD) between preplant and V5, or had soil C/N ratios > 9.7:1; otherwise, V5 PMN an tended to be greater than preplant PMN an. The PMN an tended to be greater in unfertilized vs. fertilized soil in sites with clay content > 9.5%, total C < 24.2 g kg −1 , soil organic Abbreviations: AWDR, Abundant and well-distributed rainfall; GDD, Growing degree-day; PMN an , Anaerobic potentially mineralizable N; SDI, Shannon diversity index; SOM, Soil organic matter. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.