The objective was to determine the effect of liming on the net ammonification and nitrification in the field of 26 acid soils during the first year after application. The soils ranged from pH 4.4 to 6.0 and were limed to a target pH of 6.7. The 26 sites were located in Alberta and northeastern British Columbia. Soils were limed in the spring, fallowed and sampled in the next spring. The content of NH4+‐N plus NO3‐‐N in the 0–15 cm layer of the non‐limed treatments varied from 6 to 48 Hg/g (average of 26), while the limed treatment varied from 14 to 89 μg/g (average of 40). The increase in ammonification was negatively related to soil pH and positively related to soil total N (R=0.66**). The proportion of NH4+‐N in the mineral‐N varied among the non‐limed samples, but it was not related to soil pH. The same was true among the limed samples. This field study suggests that for at least a year after liming both the increase of mineral‐N, and variation in nitrification, may complicate crop behavior in field assessment of liming.