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.

摘要

双氰胺 (DCD) 已被广泛用于延缓硝化过程和减少氮 (N) 损失。然而，它的功效是可变的并且根据环境条件而不一致。温度和湿度对钙质土壤中 DCD 降解和二氧化碳 (CO ₂ ) 释放的影响尚不为人所知。因此，在不同温度（10 °C 和 25 °C）和水分（40% 和 60% WFPS）水平下进行了包括三个处理（对照、N 肥和 N 肥 + DCD）的孵化实验 67 d。结果表明，随着氮的添加，硝化活性和随后的气体损失增加，并且受到温度和湿度水平的显着影响。DCD有效抑制NH ₄ ⁺氧化，净NO₃ ^-生产 (31–59%) 和 N ₂ O 排放 (69%)。CO ₂排放随着施氮而增加，但随着 DCD 的应用显着减少（18-161%）。DCD抑制硝化作用和控制CO ₂排放的效率与其在土壤中的停留时间有关。DCD 在高温 (25 °C) 和湿气 (60% WFPS) 下迅速降解，这就是为什么它在抑制硝化作用和控制气体通量方面效果最差的原因。因此，DCD并非在任何地方都同样有效，更适用于低温和低湿度的地区。