关键词: 双氰胺, 潮土, 砂姜黑土, 铵态氮, 硝态氮, 硝化抑制率

Abstract:

A soil incubation experiment was carried out in a conditioned chamber to study effect of dicyandiamide(DCD) inhibiting nitrification in two main types of soils(fluvo-aquic soil and lime concretion black soil) in the Huaihe River Basin. The process of urea conversion was monitored through analyzing changes in relative concentration of NH₄⁺-N and NO₃^--N and changes in inhibition strength of DCD with dosage of the habitator used were illuminated through calculating nitrification inhibition rates. Then optimal DCD dosages were figured out for different soils. Results indicate that in both soils DCD inhibited nitrification effectively, and within the range of DCD dosages(2%-10%) set for the incubation experiment, the effect increased with rising DCD dosage. In the fluvo-aquic soil, the nitrification inhibition rate reached as high as 58.9%, while in the lime concretion black soil, it was much lower, being 27.4% only, and the difference between the two soil was not so significant when the DCD dosage was 8%(P<0.05). In the fluvo-aquic soil, the concentration of NH₄⁺-N decreased to 14.4 mg·kg^-1 after 42 days of incubation, whereas in the lime concretion black soil the concentration of NH₄⁺-N dropped drastically after 7 days of incubation, and became almost undetetable after 21 days. These findings indicate that DCD applied in combination with urea can prolong effect of the fertilizer in fluvo-aquic soil, but the effect is not so high in lime concretion black soil.

Key words: dicyandiamide, fluvo-aquic soil, lime concretion black soil, ammonia-nitrogen, nitrate-nitrogen, nitrification inhibition rate