三峡库区典型农耕地的氮素淋溶与评价
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国家科技部“十一五”支撑项目(2006BAD25B08)


Nitrogen leaching from farmlands typical of the Three-Gorges Reservoir Region and its evaluation
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    摘要:

    试验选择重庆市三峡库区典型、具有代表性的菜地和坡耕地,于2005至2007年将改进后的离子交换树脂吸附装置分别埋入20 cm、30 cm、40 cm深度的土壤中,中雨、大雨之后或按月收集树脂吸附的NO3--N和NH4+-N,连续三年原位定点研究了两种土壤的氮素淋溶状况。结果表明,菜地的氮素淋失量(74.58 kg hm-2 a-1)高于降雨输入量(56.9 kg hm-2 a-1),坡耕地的(46.01 kg hm-2 a-1)则相反,说明菜地的氮素淋失局部影响当地水环境,农耕地可能不是区域水体富营养化的主要原因。NO3--N占土壤氮素总淋溶量的90%以上,主要发生在施肥后的第一次中雨、大雨中。此外,NO3--N淋溶量耕作层>心土层>底土层,前者远远高于后两者。在整个降雨季节,土壤NO3--N淋溶量前期高,峰值出现在5月份;在雨季后期,土壤NO3--N淋失量很低,故对水体的影响甚小。NO3--N淋溶与土壤碱解氮呈指数正相关。由此可见,三峡库区降低土壤氮素淋溶的主要对象是菜地,有效措施包括控制氮肥用量,降低土壤有效氮库,抑制硝化作用等。

    Abstract:

    An in-situ field experiment was carried on to study nitrogen leaching from farmlands typical of the Three-Gorges Reservoir Region of Chongqing for three successive years (from 2005 to 2007),using modified apparatuses packed with ion exchange resin and buried into the soil at the depth of 20 cm,30 cm and 40 cm,separately to adsorb NO3--N and NH4+-N and hence to monitor nitrogen leaching from the two soils monthly and after each moderate and heavy rainfall event. It was found that nitrogen leaching from vegetable field (74.58 kg hm-2 a-1) was higher but that from on slope farmland (46.01 kg hm-2 a-1) was lower than nitrogen input (56.9 kg hm-2 a-1) with rainfall into the fields,which indicates that nitrogen leaching from vegetable fields may partially affect the local water environment,but the farmland as a whole may not be the major cause of eutrophication of the local water system.Of the total nitrate leached from the soil more than 90% was NO3--N and its leaching occurred mainly during the first moderate or heavy rainfall event after fertilization.And NO3--N leaching from soil layers followed the sequence of cultivated layer > subsoil layer > bottom layer,and the former was much higher than the latter two.Moreover,it concentrated mainly in the early part of the rainy season,peaking in May,and stayed low in the later part,rendering limited impact on waterbody.A positive exponent correlation was observed between nitrate leaching and soil alkalyzed N. Therefore,it seems that vegetable fields are the major object for control of soil N leaching and effective measures may include control of nitrogen fertilization rate,reduction of soil available nitrogen pool and suppression of nitrification in the soil.

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袁玲,王容萍,黄建国.三峡库区典型农耕地的氮素淋溶与评价[J].土壤学报,2010,47(4):674-683. DOI:10.11766/trxb200906140259 yuan ling. Nitrogen leaching from farmlands typical of the Three-Gorges Reservoir Region and its evaluation[J]. Acta Pedologica Sinica,2010,47(4):674-683.

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  • 收稿日期:2009-06-14
  • 最后修改日期:2010-01-18
  • 录用日期:2010-01-18
  • 在线发布日期: 2010-06-13
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