施肥方式对设施菜地氨挥发的影响

Effects of Fertilization Methods on Ammonia Volatilization from Vegetable Field Under Greenhouse Cultivation

【目的】针对我国设施菜地氨(NH_(3))挥发过高的问题,研究不同施肥方式下设施菜地NH_(3)挥发特征,分析各施肥方式下影响设施菜地NH_(3)挥发的重要因子,为以减氮增效为目标的设施菜地肥料管理模式制定提供相关科学依据。【方法】以长江中下游地区典型设施菜地为研究对象,基于1次基肥和2次追肥的施肥方式,设置了不施氮处理(Control)、常规施氮处理(CF)、20%减氮缓释肥处理(SF)、20%减氮有机/无机肥配施处理(OF)、20%减氮复合微生物菌肥/无机肥配施处理(MF)和20%减氮水肥一体化处理(IM),共计6个田间试验处理。除Control处理外,其余各处理氮磷钾的全季施用比例均保持一致。使用通气法对不同施肥方式下的菜地NH_(3)挥发进行了原位监测,并同步分析不同施肥方式下可能影响菜地土壤NH_(3)挥发的相关因素。【结果】不同施肥方式处理下的菜地NH_(3)挥发动态基本一致,NH_(3)挥发峰值均出现在肥料施用后。基肥施用阶段,除IM处理在基肥施用1 d后NH_(3)挥发即达到峰值外,其余处理均在基肥施用后3 d达到NH_(3)挥发峰值,峰值范围为0.12—0.26 kg NH_(3)·hm^(-2)·h^(-1)。在追肥阶段,各处理NH_(3)挥发峰值出现时间均有不同程度提前,各处理的NH_(3)挥发通量在追肥-Ⅰ阶段的峰值范围为0.08—0.19 kg NH_(3)·hm^(-2)·h^(-1),追肥-Ⅱ阶段的峰值范围为0.13—0.18 kg NH_(3)·hm^(-2)·h^(-1)。NH_(3)挥发累积排放量由高至低依次为CF、MF、OF、SF、IM、Control。与CF施肥处理相比,SF和IM处理分别降低菜地累积NH_(3)挥发量24.2%和42.4%(P<0.05),OF和MF处理分别降低10.1%和8.3%(P>0.05)NH_(3)挥发累积量。此外,由NH_(3)挥发引起的氮肥损失率,由高至低依次为MF、OF、CF、SF、IM。与CF处理相比,MF处理始终具有较高的肥料NH_(3)-N损失率,而IM处理下则始终低于CF处理。与CF处理相比,SF和OF处理在基肥阶段的肥料NH_(3)-N损失率较低,但在追肥阶段的肥料NH_(3)-N损失率则均高于CF处理。【结论】与CF处理相比,SF和IM处理可显著降低设施菜地NH_(3)挥发量。从不同施肥阶段来看,IM处理在基肥和追肥施用阶段均可显著降低由NH_(3)挥发引起的氮肥损失率,而SF处理对菜地NH_(3)挥发的减缓作用主要是在基肥施用阶段。因此,缓释氮肥施用以及水肥一体化技术在减缓设施菜地NH_(3)挥发和农田减氮增效方面,具有重要的推广意义。

【Objective】The massive ammonia (NH_(3)) volatilization from excessive nitrogen (N) fertilization is a common issue in greenhouse cultivated vegetable production in China.To alleviate this problem,a field experiment was conducted to study the effects of different fertilization methods on NH_(3)volatilization of greenhouse vegetable fields.【Method】The study was carried out with 6fertilization treatments via one-time basal fertilization and two-time topdressings,including N fertilizer-blank treatment (Control),conventional fertilization treatment (CF),20%N-reduced slow-release fertilizer treatment (SF),20%N-reduced organic fertilizer treatment (OF),20%N-reduced microbial fertilizer treatment (MF) and integrated management of water and fertilizer treatment (IM).Except for the Control treatment,an identical application ratio of N,P and K fertilizers was employed to each treatment throughout the whole vegetable growing season.The NH_(3)volatilization fluxes under different fertilization methods were observed by using venting absorption method.The potential influencing factors of NH_(3)volatilization were also investigated synchronously.【Result】The dynamics of NH_(3)volatilization under different fertilization treatments were similar,and the occurrence of the peaks of NH_(3)flux was highly associated with fertilization time.During basal fertilization period,for the most of treatments,the NH_(3)fluxes peaks appeared3-days after the application of basal fertilizer,while it was only 1-day under IM treatment.The maximum fluxes of NH_(3)ranged from0.12 to 0.26 kg NH_(3)·hm^(-2)·h^(-1);during basal fertilization period.The occurrence of the peaks of NH_(3)fluxes were ahead by 1-2 days during topdressing periods.The maximum fluxes of NH_(3)volatilization were 0.08-0.19 kg NH_(3)·hm^(-2)·h^(-1) during the first topdressing period,and 0.13-0.18 kg NH_(3)·hm^(-2)·h^(-1);during second topdressing period.Significant differences were found among different fertilization treatments in the seasonal cumulative NH_(3)volatilizations.The seasonal cumulative NH_(3)volatilizations in the decreasing order of different treatments were CF,MF,OF,SF,IM,Control.Compare with CF treatment,the treatments of SF and IM markedly reduced NH_(3)volatilization from greenhouse vegetable field by 24.2%and 42.4%(P<0.05),and reduced by 10.1%and 8.3%(P>0.05) under MF and OF treatments,respectively.The NH_(3)volatilization-induced N losses in the decreasing order of different treatments were MF,OF,CF,SF,IM.Compare with the rest of the applied treatments,the IM treatment consistently showed lower NH_(3)-N loss rate during the whole season.However,the NH_(3)-N loss rates under MF and OF treatments were different during basal fertilization and topdressing periods.In the basal fertilization period,the MF and OF treatments showed lower NH_(3)-N loss rates compare with CF treatment,however,during topdressing period,the NH_(3)-N loss rates under MF and OF treatments were higher than that under CF treatment.【Conclusion】Compare with CF treatment,both of the SF and IM treatments could significantly reduce the NH_(3)volatilization that derived from applied N fertilizer.The IM treatment reduced NH_(3)-N-induced N fertilizer loss in both basal fertilization and topdressing periods,while the SF treatment mainly reduced the NH_(3)volatilization during basal fertilization period.On balance,both the application of slow-release fertilizer and the technique of integrated management of water and fertilizer were the effective ways in the reduction of NH_(3)volatilization from greenhouse vegetable field,and were worthy for recommendation.