Dicyandiamide efficacy of inhibiting nitrification and carbon dioxide emission from calcareous soil depends on temperature and moisture contents

ABSTRACT

Dicyandiamide (DCD) has been extensively used to retard the nitrification process and decrease nitrogen (N) losses. However, its efficacy is variable and inconsistent depending upon the environmental conditions. The effects of temperature and moisture on DCD degradation and carbon dioxide (CO₂) release from calcareous soil are not well-known. Therefore, an incubation experiment comprising three treatme ts (control, N fertilizer, and N fertilizer + DCD) was conducted for 67 d at different temperature (10 °C and 25 °C) and moisture (40% and 60% WFPS) levels. Results showed that nitrification activity and subsequent gaseous losses were increased with N addition and significantly affected by temperature and moisture levels. DCD effectively inhibited NH₄⁺ oxidation, net NO₃⁻ production (31–59%), and N₂O emissions (69%). CO₂ emissions increased with N fertilization but reduced (18–161%) significantly with DCD application. DCD efficiency of inhibiting nitrification and controlling CO₂ emission was related to its residence time in the soil. DCD degraded quickly at high temperature (25 °C) and moisture (60% WFPS), that is why it was least effective in inhibiting nitrification and controlling gaseous fluxes. Accordingly, DCD is not equally effective everywhere and is more suitable for regions with low temperature and low moisture.

KEYWORDS:

• Nitrification process
• dicyandiamide degradation
• co₂ emission
• nitrous oxide
• soil inorganic carbon
• soil acidification

Acknowledgements

This work was supported by the National Natural Science Foundation of China (41671295), the National Key R & D Program of China (No. 2017YFD0200106), and the 111 Project (No. B12007).

Disclosure statement

The authors declare no conflicts of interest.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (41671295), the National Key R & D Program of China (No. 2017YFD0200106), and the 111 Project (No. B12007).