Spatial Variability of Nitrogen Content in Topsoil and Nitrogen Distribution in Vadose Zones and Groundwater Under Different Types of Farmland Use in Beijing, China
Spatial Variability of Nitrogen Content in Topsoil and Nitrogen Distribution in Vadose Zones and Groundwater Under Different Types of Farmland Use in Beijing, China
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DOI：
10.1166/sl.2014.3117
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发表时间：
2014-03
期刊：
影响因子：
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通讯作者：
Fangze Shang;Peiling Yang;S. Ren;Q. Wang;Yunkai Li;Yichen Li;Danchi Xi
中科院分区：
文献类型：
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作者：
Fangze Shang;Peiling Yang;S. Ren;Q. Wang;Yunkai Li;Yichen Li;Danchi Xi
土壤NO、−3-N、NH+4-N和总氮(TN)的空间变异性受农田利用类型的影响较大，对农业管理和环境保护具有重要意义。关于不同类型农田(菜地、果园和农田)表层土壤NO-−3-N、NH+4-N和TN的空间格局及其与包气带土壤氮和地下水NO-−3-N的关系的研究较少。中国，从北京市海淀区采集了61个表层土壤(0~25 cm)、162个包气带(0~200 cm)土壤和35个地下水样品。利用地统计学方法和地理信息系统对不同农田利用方式下表层土壤NO、−3-N、NH+4-N和TN的空间异质性进行了表征和比较，并研究了不同农田利用方式下表层土壤、包气带和地下水之间的氮素含量关系。结果表明，表层土壤NO、−3-N和NH+4-N含量呈正态分布，而TN含量呈对数正态分布。不同农田利用方式下，表层土壤NH+4-N和TN均表现出中等变异性，而非−3-N表现出较强的变异性。对土壤NO-−-3-N影响最大的是施肥、灌溉等人类活动。农田利用类型对土壤中P−3-N、NH+4-N和TN含量有显著影响(P<0.0 5)，地下水中无−3-N含量。不同农田利用方式下，表层土壤中NO−3-N含量和地下水中NO−3-N含量均呈相同的递减顺序(菜地和果园)，土壤NH+4-N含量在表土和0~2 0 0 cm包气带(农田和果园及蔬菜)中呈现相同的递减顺序。然而，土壤全氮含量并不遵循这一顺序。菜地氮肥施用量最高，表土和包气带中氮素含量最高，地下水中氮素含量最高。因此，菜地对地下水的污染潜力最大。农田土壤中NO-−-3-N浓度与地下水埋深呈对数关系。综合考虑环境和农田利用类型，提出沙区和无隔水土层的地区不宜种植蔬菜。
The spatial variability of soil NO− 3–N, NH+ 4–N and total nitrogen (TN), which can be greatly affected by farmland use types, are vital for agricultural management and environmental protection. To data, only few studies have been down to investigate the spatial patterns of soil NO− 3–N, NH+ 4–N and TN in topsoil and their relationships with vadose zone soil nitrogen and groundwater NO− 3–N under different types of farmland use (vegetable field, orchard and cropland). We collected 61 topsoil (0–25 cm) samples, 162 vadose zone (0–200 cm) soil samples and 35 groundwater samples from Haidian district of Beijing, China. Geostatistical method and ArcGIS were used to characterize and compare the spatial heterogeneities of topsoil NO− 3–N, NH+ 4–N and TN and to study the nitrogen content relationships among topsoil, vadose zones and groundwater under different types of farmland use. The results indicated that the contents of topsoil NO− 3–N and NH+ 4–N were normally distributed, while TN was lognormally distributed. Both topsoil NH+ 4–N and TN showed moderate variability, while NO− 3–N showed strong variability under different types of farmland use. The greatest influence on soil NO− 3–N was from human activity like fertilization and irrigation. The type of farmland use had significant (P − 3–N, NH+ 4–N and TN contents in soils, and NO− 3–N concentrations in groundwater. The NO− 3–N content in topsoil and NO− 3–N concentration in groundwater under different types of farmland use showed the same descending order (vegetable field > orchard > cropland), and the soil NH+ 4–N content showed the same descending order in topsoil and 0–200 cm vadose zone (cropland > orchard > vegetable). However, the soil TN content didn't follow that order. Vegetable fields had the highest N fertilizer rates, and consequently they also had the highest contents in topsoil and vadose zones and highest concentrations in groundwater. Thus, vegetable fields had the biggest pollution potential in groundwater. At last, a logarithmical relationship between NO− 3–N concentrations and groundwater depths was found in farmland areas. Taking environment and the types of farmland use into account, we propose sandy areas and areas without water-resisting soil layers are not suitable for planting vegetables.