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Nitrification inhibition of soil and applied fertilizer N is desirable as the accumulation of nitrates in soils in excess
of plant needs leads to enhanced N losses and reduced fertilizer N-use efficiency. In a growth chamber experiment, we studied
the effects of two commercial nitrification inhibitors (NIs), 4-amino 1,2,4-triazole (ATC) and dicyandiamide (DCD), and a
commonly available and economical material, encapsulated calcium carbide (CaC2) (ECC) on the nitrification of soil and applied NH4
+-N in a semiarid subtropical Tolewal sandy loam soil under upland [60% water-filled pore space (WFPS)] and flooded conditions
(120% WFPS). Nitrification of the applied 100 mg NH4
+-N kg–1 soil under upland conditions was retarded most effectively (93%) by ECC for up to 10 days of incubation, whereas for longer
periods, ATC was more effective. After 20 days, only 16% of applied NH4
+-N was nitrified with ATC as compared to 37% with DCD and 98% with ECC. Under flooded soil conditions, nitrates resulting
from nitrification quickly disappeared due to denitrification, resulting in a tremendous loss of fertilizer N (up to 70% of
N applied without a NI). Based on four indicators of inhibitor effectiveness, namely, concentration of NH4
+-N and NO3
–-N, percent nitrification inhibition, ratio of NH4
+-N/NO3
–-N, and total mineral N, ECC showed the highest relative efficiency throughout the 20-day incubation under flooded soil conditions.
At the end of the 20-day incubation, 96%, 58% and 38% of applied NH4
+-N was still present in the soil where ECC, ATC and DCD were used, respectively. Consequently, nitrification inhibition of
applied fertilizer N in both arable crops and flooded rice systems could tremendously minimize N losses and help enhance fertilizer
N-use efficiency. These results suggest that for reducing the nitrification rate and resultant N losses in flooded soil systems
(e.g. rice lowlands), ECC is more effective than costly commercial NIs.
Received: 25 May 2000 相似文献
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