NH3 volatilization is an important process of N loss from fertilizer nitrogen (N) applied to no-tillage rice fields. It has been demonstrated that no-tillage promotes NH3 volatilization. However, few studies have been conducted to investigate the effects of N management on NH3 volatilization from no-tillage paddy fields. Therefore, a field experiment was conducted on a clay loam soil (Anthrosol, World Reference Base for Soil Resources) to study the effects of N management on NH3 volatilization and N use efficiency from no-tillage rice fields in the city of Wuxue in central China during the 2012 rice- growing season. In this study, five experimental treatments were arranged in a completely randomized design with three replications. Five treatments were applied including five application rates of N fertilizer in the seedling, mid-tillering, flowering and heading stages of rice: 2:2:3:3 (R1), 3:2:2:3 (R2), 4:2:2:2 (R3), 4:3:1:2 (R4) and 0:0:0:0 (CK). The NH3 volatilization fluxes were determined 20 times using a venting method during the 2012 rice growing season. NH+4 concentrations and pH of the soils and field surface water were also measured. The obtained results showed that application of N fertilizer significantly enhanced both NH+4 concentrations of the soils and field surface water and the soil pH. Compared with the other fertilized treatments (R2, R3 and R4), R1 significantly decreased NH+4 concentrations of the soils and field surface water. In the fertilized treatments, during the rice growing season, each application of N fertilizer led to NH3 volatilization fluxes peaking after 1-3 days, and then dropping rapidly to those in the unfertilized treatment levels within 1-2 weeks. The NH3 volatilization fluxes in the CK treatment were relatively low, and remained nearly unchanged. The NH3 volatilization fluxes ranged from 2.0 to 21.94 mg·m-2·d-1 for the CK treatment and from 2.21 to 209.6 mg·m-·2 d-1 for the fertilized treatments. Mean NH3 volatilization fluxes in the R1, R2, R3 and R4 treatments were (13.8±2.0), (15.3± 0.2), (15.8 ±0.1) and (14.2 ±0.1) mg·m-2·d-1, respectively, which were 1.57, 1.81, 1.88 and 1.69 times, respectively, that in the CK treatment. The cumulative amounts of NH3 volatilization were (8.52±0.20) (CK), (19.59± 2.30) (R1), (21.85±0.68) (R2), (21.98±0.45) (R3) and (23.79±1.15) kg N/ hm2(R4). For fertilized treatments, the highest cumulative NH3 volatilization was observed at the mid-tillering stage (accounting for 11.9%-14.7% of the total), followed by the heading stage, with the minimum being found at the seeding and booting stages. Compared with no N fertilizer, application of N fertilizer significantly increased NH3 volatilization by 56.5%-64.2% from the no-tillage paddy fields. In fertilized treatments, N losses through NH3 volatilization accounted for 6.2%-8.5% of the applied N. Among the four fertilized treatments, the cumulative NH3 volatilization was significantly reduced by 9.1%-17.7% under R1 than under the other fertilized treatments. Linear correlation analysis indicated that NH+4 concentrations and pH in the soils and field surface water were significantly related to the NH3 volatilization fluxes. Application of N fertilizer significantly affected N uptake of rice, where, compared with the CK treatments, fertilized treatments significantly increased N uptake of rice by 46.5%-89.3%. Compared with the other fertilized treatments, R1 significantly enhanced N use efficiency by 28.4%- 74.9%. Therefore, our results suggest that N application at the late growth stage of rice can decrease NH3 volatilization, thus improving N use efficiency of rice under no-tillage rice fields.
CITATION STYLE
Ma, Y. H., Liu, B., Zhang, Z. S., Zheng, D., Zhou, L., Cao, C. G., & Li, C. F. (2013). Effects of nitrogen management on NH3 volatilization and nitrogen use efficiency under no-tillage paddy fields. Shengtai Xuebao/ Acta Ecologica Sinica, 33(18), 5556–5564. https://doi.org/10.5846/stxb201304020589
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