Table 1.
Physicochemical properties of the three agricultural soils (0–20 cm soil layers).
Fig 1.
Dynamic changes of NH4+-N and NO3−-N of different treatments in three soils.
Treatment: Control, no fertilizer and nitrification inhibitors; AS, ammonium sulphate; AD, AS+3, 4-dimethylpyrazole phosphate (DMPP); AN, AS+nitrogen protectant (N-GD); ADN, AS+3, 4-dimethylpyrazole phosphate (DMPP)+nitrogen protectant (N-GD). Error bars represented standard deviations (n = 3).
Table 2.
Three-way ANOVA (P < 0.05) of soil types (S), nitrification inhibitor (NI) and days after planting (D) and their interactions ((S*NI), (S*D), (NI*D) and (S*NI*D)) on the content of NH4+-N, NO3—N and apparent nitrification rate (ANR).
Fig 2.
Changes of apparent nitrification rate of three soils during four sampling periods.
Treatment: AS, ammonium sulphate; AD, AS+3, 4-dimethylpyrazole phosphate (DMPP); AN, AS+nitrogen protectant (N-GD); ADN, AS+3, 4-dimethylpyrazole phosphate (DMPP)+nitrogen protectant (N-GD). Error bars represented standard deviations (n = 3).
Fig 3.
Aboveground biomass of maize under different treatments in three soils.
Treatment: AS, ammonium sulphate; AD, AS+3, 4-dimethylpyrazole phosphate (DMPP); AN, AS+nitrogen protectant (N-GD); ADN, AS+3, 4-dimethylpyrazole phosphate (DMPP)+nitrogen protectant (N-GD). Error bars represented standard deviations (n = 3). Different letters indicate significant differences between different treatments at P < 0.05 by Duncan test.
Table 3.
Two-way ANOVA (P < 0.05) of soil types (S) and nitrification inhibitor (NI) on grain yield, agronomic nitrogen use efficiency (ANUE) and apparent nitrogen recovery (AR) of maize.
Fig 4.
Nitrogen uptake of maize under different treatments in three soils.
Treatment: AS, ammonium sulphate; AD, AS+3, 4-dimethylpyrazole phosphate (DMPP); AN, AS+nitrogen protectant (N-GD); ADN, AS+3, 4-dimethylpyrazole phosphate (DMPP)+nitrogen protectant (N-GD). Error bars represented standard deviations (n = 3). Different letters indicate significant differences between different treatments at P < 0.05 by Duncan test.
Fig 5.
Nitrogen use efficiency (ANUE and AR) under different treatments in three soils.
ANUE, agronomic nitrogen use efficiency; AR: Apparent nitrogen recovery. Treatment: AS, ammonium sulphate; AD, AS+3, 4-dimethylpyrazole phosphate (DMPP); AN, AS+nitrogen protectant (N-GD); ADN, AS+3, 4-dimethylpyrazole phosphate (DMPP)+nitrogen protectant (N-GD). Error bars represented standard deviations (n = 3). Different letters indicate significant differences between different treatments at P < 0.05 by Duncan test.
Table 4.
Pearson correlation between soil pH, soil organic matter (SOM), NH4+-N and NO3—N.