*3.2. Total Emissions of CO2-C and N2O-N*

Total CO2-C emission during the incubation period was significantly higher from Marsch soil (274 mg kg−1) than Östliches Hügelland soil (54.6 mg kg−1) and Geest soil (60.3 mg kg−1) (Table 3). In Marsch soil, DMPP showed the highest inhibitory effect on CO2 emission (50%), followed by PIADIN (32%) and the lowest by ENTEC (16%). DCD did not influence CO2-C emission from Marsch soil (Table 3). In Östliches Hügelland soil, DCD and PIADIN showed the highest and equal inhibitory effect on CO2 emission (73%), followed by DMPP (64%) and the lowest by ENTEC (36%). The effect of the NIs on CO2 emission from Geest soils was nonsignificant.

**Table 3.** Total CO2-C emission during the incubation period from Marsch, Östliches Hügelland and Geest soils with control, DCD, DMPP, ENTEC and PIADIN applied under controlled conditions.


The values (mean ± SE) are means of four independent pot replicates. The values indicated with the same lowercase letter(s) are not significantly different at *p* = 0.05.

Total N2O-N emission was also the highest from Marsch soil (8051 μg kg<sup>−</sup>1), followed by Östliches Hügelland soil (3516 μg kg−1) and the lowest from Geest soil (1313 μg kg−1) (Table 4). In Marsch and Östliches Hügelland soils, DCD showed the stronger inhibitory effect on N2O-N emission (86% and 47%, respectively) compared with DMPP (56% and 30%, respectively) and PIADIN (54% and 16%, respectively). In Geest soil, DMPP was more effective in reducing N2O-N emission (88%) than PIADIN (70%) and DCD (33%).

**Table 4.** Total N2O-N emissions during the incubation period from Marsch, Östliches Hügelland and Geest soils with control, DCD, DMPP, ENTEC and PIADIN applied under controlled conditions.


The values (mean ± SE) are means of four independent pot replicates. The values indicated with the same lowercase letter(s) are not significantly different at *p* = 0.05.

#### *3.3. Soil NH4 +-N and NO3* −*-N Concentrations*

In Marsch soil, DCD, DMPP and PIADIN slowed down the nitrification process and maintained higher NH4 +-N concentration and lower NO3 −-N concentration as compared to control (Figure 3; Table 2). ENTEC did not affect NH4 +-N and NO3 −-N concentrations, which showed the same trend as that of control Marsch soil (Figure 3). NH4 +-N concentration decreased and NO3 −-N concentration increased progressively during the incubation period in control treatment of Östliches Hügelland soil, whereas DCD, DMPP and PIADIN maintained NH4 +-N concentration at high levels and kept NO3 −-N at lower levels as compared to control (Figure 3). Similarly, DCD, DMPP, ENTEC and PIADIN slowed down the decrease in NH4 +-N and the increase in NO3 −-N concentrations as compared to control in Geest soil (Figure 3). DMPP and PIADIN showed lower NO3 −-N concentration as compared to DCD and ENTEC in Geest soil (Figure 3).

**Figure 3.** Changes in NH4 +-N and NO3 −-N concentrations in Marsch, Östliches Hügelland and Geest soil with control, DCD, DMPP, ENTEC and PIADIN applied. The data values are means of four independent pot replicates, and error bars represent standard errors of the means (*n* = 4). Incubation times indicated by the same lowercase (NH4 +) or uppercase (NO3 <sup>−</sup>) letter(s) do not differ significantly at *p* ≤ 0.05.
