Fig. 2From: pH rather than nitrification and urease inhibitors determines the community of ammonia oxidizers in a vegetable soilThe variation of NO3 −-N concentrations as affected by applications of urea, nitrification inhibitor (nitrapyrin) and urease inhibitor (NBPT) at different pH levels. Error bars indicate standard deviation of mean (n = 3). a pH 3.97; b pH 4.82; c pH 6.07; d pH 7.04Back to article page