【作者】 王彩绒；

【导师】 吕家珑； 胡正义；

【作者基本信息】 西北农林科技大学 ， 土壤学， 2006， 博士

【摘要】 农业面源污染是导致太湖流域水体富营养化重要原因之一。明了该地区蔬菜地土壤氮磷向水体迁移途径、形态、通量,确定土壤氮磷流失高风险区,实施径流控制对太湖水体富营养化的治理具有重要现实意义。本研究以太湖西岸宜兴市大铺镇50 hm²蔬菜地为研究对象,在研究蔬菜地耕层土壤氮磷含量及空间分布变异特征的基础上确定了氮磷优先控制区;确定了蔬菜地磷淋溶损失的临界值,评价了研究区域土壤磷淋失的风险;观测了氮磷径流流失量,研究了生态隔离带控制土壤氮磷通过径流向水体的迁移效果。主要结果总结如下:在地统计学和地理信息系统的支持下,分析了土壤氮磷养分的空间变异特征,确定研究区域内朱渎港和林庄港沿岸地区为土壤氮磷向水体迁移高风险区域。在50hm²蔬菜地网格法（50 m×50 m）采集表层土壤样品156份,测定了土壤全氮、全磷、有效磷等参数,通过地统计学方法研究了50hm²蔬菜地表层土壤全N、全P和速效P空间变异特征,结果表明土壤全N、全P和速效P有明显的空间变异结构;全N和全P变异函数符合指数模型,速效P符合线性有基台模型;全N有强烈的空间相关性,全P和速效P有中等的空间相关性;氮磷养分的Kriging连续分布图显示,研究区域朱渎港和林庄港沿岸地区为高氮磷分布区,土壤氮磷径流向水体迁移风险大,应作为土壤氮磷向水体迁移的优先控制区。土壤磷淋失是太湖蔬菜地土壤磷向水体迁移的途径之一,太湖蔬菜地土壤磷淋失的临界值为M1-P含量60 mg/kg,研究地土壤发生磷淋失面积占总调查面积28%。当土壤M1-P<60 mg/kg（0.025MH₂SO₄-0.05MHCl）,几乎没有检测到CaCl₂浸提水溶P,而当土壤M1-P>60 mg/kg,M1-P与CaCl₂-P有极显著的线性关系,初步确定磷淋失临界值为M1-P含量60 mg/kg,土柱模拟试验也证实M1-P含量60 mg/kg为P淋失临界值的合理性。以M1-P含量60 mg/kg为临界指标,对研究区域土壤磷淋失风险进行评价,结果表明,研究区域28%田块土壤磷会通过淋失向水体迁移。土壤氮磷径流流失是蔬菜地土壤氮磷向水体迁移的途径,颗粒态氮磷是蔬菜地氮磷径流流失的主要形式。通过设置径流小区观测试验,对太湖典型蔬菜地在多次天然降雨条件下径流中氮磷的流失进行了研究。结果表明,春夏两季（2004年2-7月）5次降雨径流条件下,种植蔬菜时总氮、总磷的径流累积流失量分别为769.2 g/hm²和94.2g/hm²,颗粒态氮磷是蔬菜更多还原

【Abstract】 Nitrogen （N） and phosphorus （P） losses with agricultural non-point is one of major factors in resulting in eutrophication of surface waters. Distinguish of risk area of loss of soil N and P from vegetable fields to water body, pathways, fluxes and chemical forms of N and P in runoff from vegetable fields is critical to control eutrophication of water body. In the present study, about 50 hm² vegetable field located at Dapu town, Yixing city was selected to investigate spatial variability of soil N and P, to determine phosphorus leaching“Threshold”, and to evaluate risk of leaching loss of N and P from vegetable fields, to estimate soil N and P runoff export from vegetable fields, and to assess control efficiency of grass buffer zone on runoff export from vegetable fields into water body. Major results were summarized as bellow.In the present investigation, total 156 top layer soil samples （0～20 cm） were taken in a regular grid of 50 m by 50 m at 50 hm² area of vegetable field. Characteristics of spatial variability and distribution pattern of soil N, P were determined using GIS and geo-statistics, Spatial variation-structure of total nitrogen, total P and available P were obvious, Semivariograms for soil available P were well fitted by linear to sill model after logarithm change , Total N and total P well fitted by exponential model.Spatial correlation in total P and available P were moderate ,respectively . High– P fields appeared at shores of Zhudu, and Linzhuan harbors and these fields could be a risk area for loss of soil N, and P from vegetable land to water body, which must take measures to control loss of N and P from vegetable fields to water body.The 0.01mol.L^-1 CaCl₂ extractable P was very little from soils below 60 mg.kg^-1 M1-P （termed the change point）, however CaCl₂ extractable P above the Change-Point was linearly related to the soil Bray-P. We therefore suggest that the change point of around 60 mg.kg^-1 M1-P is a critical concentration at which leaching of P starts for the study vegetable soil. The soil columns study further revealed that it is reasonable about this change point. The critical value was to use to estimate the risk of P leaching from vegetable field to water. About 28%更多还原