摘要
摘要:明确地下水位波动对农田土壤剖面和地下水NO₃^--N运移的影响，可为减少土壤氮素淋失、降低地下水硝酸盐污染风险提供依据。本研究采用大型土柱温室种植甘蓝，研究2种水位波动（水位不变、水位每隔10 d波动20 cm）和3种施氮量[0 kg（N）·hm^-2、225 kg（N）·hm^-2、450 kg（N）·hm^-2]对土壤含水量、土壤溶液NO₃^--N浓度、地下水NO₃^--N浓度和作物产量的影响。结果表明，水位波动和施氮肥对NO₃^--N运移的影响与土壤剖面深度有关。0~20 cm包气带土壤NO₃^--N含量受施氮量影响，过量施氮肥[450 kg（N）·hm^-2]导致该剖面NO₃^--N累积。20~60 cm水位波动带土壤NO₃^--N含量受施氮量和水位波动的共同作用：施氮量增加提高NO₃^--N含量；水位波动降低剖面土壤NO₃^--N含量，水位上升和下降均促进土壤NO₃^--N随着水流运动向下层迁移；剖面土壤硝态氮含量高，增加NO₃^--N进入地下水的风险。60~80 cm淹水区剖面土壤NO₃^--N含量较低。作物产量受水位波动影响不显著。在地下水位埋深较浅的农业区进行氮素污染防控时，不可忽视水位波动对NO₃^--N运移的影响。
关键词:水位波动/
施氮量/
土壤溶液/
硝态氮/
运移/
地下水/
产量
Abstract:Understanding the effects of groundwater fluctuations on nitrate nitrogen (NO₃^--N) transport in the soil vertical profile is important for reducing nitrogen (N) leaching and nitrate pollution in croplands with shallow groundwater. This study investigated effects of groundwater fluctuations and nitrogen application rate in a greenhouse cabbage with large soil column experimental devices. Two groundwater fluctuation levels (W0, stable; W1, 20 cm fluctuation per 10 days) and three levels of nitrogen application (N0, 0 kg(N)·hm^-2; N1, 225 kg(N)·hm^-2; N2, 450 kg(N)·hm^-2) were tested to determine water contents and NO₃^--N concentration changes at different soil depths, NO₃^--N concentration in groundwater, and crop yield. The results showed that fluctuating groundwater affected NO₃^--N transport depending on the soil depth and nitrogen application rate. At 0–20 cm depth (part of the vadose zone), excessive N application led to NO₃^--N accumulation in soil, but there was no correlation with groundwater fluctuation. At 20–60 cm depth (groundwater fluctuation zone), increased N fertilizer increased the soil NO₃^--N, and groundwater level changes promoted NO₃^--N migration into deeper soil, increasing the NO₃^--N groundwater pollution risk (especially in soil with already high NO₃^--N concentrations). At 60–80 cm depth (the flooding area), there was less NO₃^--N in soil, mainly due to denitrification. Crop yield did not significantly correlate with groundwater level changes. Groundwater fluctuations affected = NO₃^--N transport and should be considered in agricultural areas with shallow groundwater levels to prevent and control nitrogen pollution.
Key words:Groundwater fluctuation/
Nitrogen application rate/
Soil solution/
Nitrate nitrogen/
Transport/
Groundwater/
Yield



PDF全文下载地址:

http://www.ecoagri.ac.cn/article/exportPdf?id=fc3cb692-3324-4dbe-8250-3c0d85186347