太湖地区农田土壤磷素动态及流失风险分析

自80年代初以来,太湖流域农田土壤(0～15 cm)磷素水平有了较大的提高, 全磷平均提高了0.1 g/kg左右,速效磷含量大多增加了4～5 mg/kg;种植经济作物的土壤由于磷盈余量大,磷素水平提高幅度更大;缺磷土壤的面积已经大大减少.与此同时,土壤磷素水平的提高增加了土壤磷向水体流失的风险.不同类型土壤的固磷能力有着较大的差别, 而区内某些固磷能力较低的土壤常常被用来种植经济作物,过量的磷素投入增加了土壤磷向水体流失的风险和流失量.     

太湖地区农田土壤磷素动态及流失风险分析

自80年代初以来，太湖流域农田土壤（0－15cm)磷素水平有了较大的提高，全磷平均提高了0．1g/kg左右，速效磷含量大多增加了4－5mg/kg；种植经济作物的土壤由于磷盈余量大，磷素水平提高幅度更大；缺磷土壤的面积已经大大减少。与此同时，土壤磷素水平的提高增加了土壤磷向水体流失的风险。不同类型土壤的固磷能力有着较大的差别，而区内某些固磷能力较低的土壤常常被用来种植经济作物，过量的磷素投入增加了土壤磷向水体流失的风险和流失量。     

有机肥施用对珠三角菜地土壤磷污染风险的初步研究

通过田间小区试验研究有机肥施用量对菜心产量、土壤磷形态的影响,分析土壤磷形态之间的相关性,评估菜地红壤磷污染风险。结果表明,有机肥施用并未提高菜心的产量和生物量,而超过一定使用量之后,反而降低菜心产量和生物量;土壤无机磷形态以Fe-P和Al-P为主,占土壤无机磷质量分数的90%以上。有机肥施用提高土壤各形态无机磷的质量分数,且有机肥用量越高,土壤Fe-P、Al-P、Ca-P和O-P质量分数越高。有机肥过量施用显著提高土壤速效磷和水溶性磷质量分数;分别对Olsen-P和CaCl2-P与各形态磷进行逐步回归分析,只有Olsen-P和CaCl2-P与Ca-P具有线性关系（p〈0.05）,方程为Y1=36.95＋0.622 1X,Y2=-0.102 5＋0.048 6X。表明施用有机肥下,Ca-P是菜地土壤有效磷的最直接来源,可以作为红壤磷污染风险评价指标。     

不同施肥水平下菜地径流氮磷流失特征

研究施肥对菜地径流氮、磷流失的影响,对控制水体富营养化有重要意义。采用田间小区监测的方法,研究常规施肥、减量施肥1和减量施肥2等三种施肥水平对菜地径流氮磷流失的影响。结果表明,（1）不同施肥水平的径流氮、磷流失浓度均较高,径流TN、NH4＋-N、NO3--N的平均流失质量浓度分别在20.5~34、2.2~2.4、6.3~9.5 mg L-1之间,径流TP、DP的平均流失质量浓度分别在7.7~11.1、2.1~2.4 mg L-1之间,菜地土壤径流氮、磷流失风险较大。（2）减量施肥可明显降低径流TN和NO3--N的流失浓度,与当地常规施肥相比,减施肥料20%和30%可分别降低径流TN流失浓度的40%、32%和NO3--N流失浓度的23%、35%,而减量施肥对径流TP、DP的流失浓度影响不大。（3）不同施肥水平的径流TN、NO3--N流失负荷分别在5.8~7.6、1.6~2.3 kg hm-2之间,与常规施肥相比,减施肥料20%和30%可分别减少TN、NO3--N流失负荷的24%、19%和11%、29%。不同施肥水平的径流TP、DP流失负荷分别在1.7~2.9、2.5~2.7 kg hm-2之间,减量施肥并不能减少径流TP、DP的流失负荷。     

不同施肥水平下菜地耕层土壤中氮磷淋溶损失特征

采用负压式土壤溶液取样器采集不同施肥水平(常规、减量20%和减量30%施肥处理,即N1、N2和N3)下城郊菜地耕层土壤(10、20和30 cm)的淋溶液,分析了总氮(TN)、硝态氮(NO_3~-)、铵态氮(NH_4~+)、总磷(TP)和溶解态磷(DP)浓度,旨在研究不同施肥水平下菜地不同耕层土壤中氮素与磷素的淋溶损失特征。研究结果:(1)不同施肥水平下,菜地耕层土壤TN、NO_3~-、NH_4~+、TP和DP淋溶质量浓度范围分别为5.24~292、3.47~271、0.16~9.47、1.66~20.6和1.63~17.7mg·L~(-1),平均质量浓度分别为38.9~113、36.0~105、1.01~2.13、3.75~12.7和3.55~11.8 mg·L~(-1);(2)氮素主要以NO3-形式发生淋溶损失,作物生长初期是菜地耕层土壤氮素淋溶损失的主要时期;减量施肥30%能有效降低耕层土壤氮素的淋溶损失,其TN和NO_3~-的淋溶质量浓度较常规施肥处理分别显著降低了58.4%和59.0%(P0.05);不同深度耕层土壤中TN和NO3-淋溶质量浓度没有显著性差异(P0.05);(3)磷素主要以DP形式发生淋溶损失,耕层土壤中TP和DP的淋溶质量浓度为20 cm10 cm30 cm(P0.05);减量20%和减量30%施肥均能有效降低耕层土壤中磷素的淋溶损失,减量20%施肥处理TP和DP的淋溶质量浓度分别显著下降了27.8%和27.6%(P0.05),而减量20%施肥处理TP和DP的淋溶质量浓度分别显著降低了44.6%和43.8%(P0.05)。结果表明,城郊菜地耕层土壤中氮素和磷素养分存在一定的淋失风险,减量施肥措施能有效降低菜地耕层土壤中氮素与磷素的淋溶损失,是降低耕层土壤氮磷淋失风险的有效措施。     

崇明东滩旱作农田土壤磷素流失及其影响因素

对采用不同施肥和地表管理方式的梨园和菜地磷素的流失进行监测,研究了崇明东滩旱作农田土壤磷素的流失负荷、流失途径及其变化规律和影响因素,并分析了不同施肥和地表管理方式对农田土壤磷素流失的影响.结果表明,旱作农田土壤磷素径流流失、渗漏流失和泥沙流失浓度均超过水体富营养化总磷浓度临界值;土壤磷素流失以泥沙流失为主,泥沙总磷流失负荷占总磷流失总负荷的70.7%～82.2%;磷素流失主要发生在6、8和10月,这3个月总磷流失负荷占全年总磷流失总负荷的71.6%～73.0%.对磷素流失影响因素的相关分析表明,旱作农田土壤磷素流失与降雨量、降雨侵蚀力、径流量、径流水中总磷浓度等因素相关显著.与常规对照方式相比较,保持表土植被、覆盖地膜和精确滴灌,可减少旱作农田径流和泥沙产生量,降低总磷流失浓度,梨园和菜地总磷流失负荷消减率分别可达20.6%和12.6%.     

集约化蔬菜地土壤磷素累积特征及流失风险

以南京市郊集约化蔬菜长期种植基地为对象,采集蔬菜种植年限分别为3~5、15~20、25~30 a的土壤,测定土壤全磷(TP)、速效磷(Olsen-P)、水溶性磷(CaCl2-P)、生物有效磷(NaOH-P)的含量,并对0—20 cm土层磷素吸附特性进行分析,通过研究土壤磷吸附饱和度(DPS)、最大缓冲容量(MBC)来对土壤磷素流失风险进行评估。结果表明,在0—20 cm土层,除NaOH-P外,其余各形态磷(TP、Olsen-P、CaCl2-P)都随种植年限延长呈增加趋势。不同种植年限土壤TP、Olsen-P、CaCl2-P、NaOH-P主要积累在0—20 cm土层,且随着土层深度的增加土壤磷的累积量逐渐降低。DPS随种植年限延长而升高,种植年限25~30 a的菜地0—5 cm土层DPS超过土壤磷素流失环境敏感指标临界值(25%),其MBC也最低,表明随着蔬菜种植年限的延长土壤磷素流失风险加剧,且流失风险主要体现在0—5 cm土层。     

北京地区部分农田土壤无机磷形态分析

为了解北京地区部分农田土壤磷赋存形态及其含量,选取了北京多区县农田为采样区域,采集土壤样品62个,测定了全磷、二钙磷、八钙磷、铝磷、铁磷、闭蓄态磷和十钙磷含量.结果表明,采样区域的土壤样品基本处于富磷状态,全磷含量为549.4—2474.8 mg·kg-1;有效磷(二钙磷)和作为第二有效磷源的铝磷、铁磷含量偏高,而潜在磷源(闭蓄态磷及十钙磷)含量偏低.为此,应注意有效利用土壤中的有效磷及第二有效磷源,兼顾节约用磷和降低磷的径流流失风险.     

有机肥与磷肥配施对滨海盐渍化土壤磷素淋洗风险的影响

针对滨海盐渍化土壤水稻种植过程中出现的磷素淋洗风险,采用田间微区试验,研究了不同用量有机肥和磷肥对滨海盐渍化土壤有效磷含量及磷素淋洗风险的影响。试验设磷肥与有机肥两个因素,3个磷(P_2O_5)水平,分别为P0:无磷,0kg·hm~(-2);P1:低磷,64 kg·hm~(-2);P2:高磷,128 kg·hm~(-2)。3个有机肥(碳)水平,分别为C0:无碳(有机肥0 kg·hm~(-2));C1:低碳,450 kg·hm~(-2)(有机肥1 000 kg·hm~(-2));C2:高碳,900 k·hm~(-2)(有机肥2 000 kg·hm~(-2))。共设7个处理:T1:无磷施用;T2:低磷;T3:高磷;T4:低碳低磷;T5:低碳高磷;T6:高碳低磷;T7:高碳高磷。结果表明,磷肥施用显著提高了土壤剖面中H2O-P、Na HCO3-P含量;低磷低碳处理下0~20 cm土层土壤中磷饱和度(DPS)较低磷处理低,其他土层土壤中磷饱和度无显著变化;而低磷高碳处理可显著提高40~60 cm土层土壤中磷饱和度,高于28.1%的临界饱和度;高磷低碳处理表层土壤有效磷含量为31.8 mg·kg~(-1),对整个剖面土壤中磷饱和度影响不大,磷素淋洗风险较小;而高磷高碳处理在提高表层土壤有效磷含量的同时,显著提高了20~40、40~60 cm土层土壤中磷饱和度,且均高于临界饱和度,导致整个土壤剖面具有很高的磷素淋失风险。在滨海盐渍化土壤水稻种植中,配施450 kg·hm~(-2) C和64 kg·hm~(-2) P_2O_5(碳磷比为15.1)时,磷素淋洗风险较低,而过量施用磷肥和有机肥将导致土壤磷素淋洗,利用效率降低。     

广州北部山区农业土地利用方式与水资源氮素含量的关系

城市的发展给广州北部山区的环境带来了一些负面的影响。为探讨农业土地利用方式与水资源氮素含量的关系,通过取样调查,结果表明：在不同利用方式的土壤渗出水中,平均总氮质量浓度依菜地、水田、砂糖桔园、荒山林、油茶林而逐渐减少;油茶林和砂糖桔园的土壤渗出水未检出铵态氮（NH4+-N）;较少受到扰动的油茶林的土壤渗出水硝态氮（NO3--N）质量浓度较低。结论如下：1）广州北部山区土地利用方式应控制或清退规模集约化菜场;2）广州北部山区可实行油茶种植生产方式,这可能是平衡农民收益与环境保护的一种有效模式;3）山区土地利用不宜大量翻动土壤,以减少 NH4+-N 在土壤渗出水中的出现而造成流失和污染。     

Influence of fertilizer and sewage sludge compost on yield and heavy metal accumulation by lettuce grown in urban soils

Previous research has demonstrated that many urban soils are enriched in Pb, Cd and Zn. Culture of vegetable crops in these soils could allow transfer of potentially toxic metals to foods. Tanya lettuce (Lactuca sativa L.) was grown in pots of five urban garden soils and one control agricultural soil to assess the effect of urban-soil metal enrichment, and the effect of soil amendments, on heavy metal uptake by garden vegetables. The amendments included NPK fertilizer, limestone, Ca(H₂PO₄)₂, and two rates of limed sewage sludge compost. Soil Cd ranged from 0.08 to 9.6 mg kg^–1; soil Zn from 38 to 3490 mg kg^–1; and soil Pb from 12 to 5210 mg kg^–1. Lettuce yield on the urban garden soils was as great as or greater than that on the control soil. Lettuce Cd, Zn and Pb concentrations increased from 0.65, 23, and 2.2 mg kg^–1 dry matter in the control soil to as high as 3.53, 422 and 37.0 mg kg^–1 on the metal-rich urban garden soils. Adding limestone or limed sewage sludge compost raised soil pH and significantly reduced lettuce Cd and Zn, while phosphate fertilizer lowered soil pH and had little effect on Zn but increased Cd concentration in lettuce. Urban garden soils caused a significant increase in lettuce leaf Pb concentration, especially on the highest Pb soil. Adding NPK fertilizer, phosphate, or sludge compost to two high Pb soils lowered lettuce Pb concentration, but adding limestone generally did not. On normally fertilized soils, Pb uptake by lettuce was not exceptionally high until soil Pb substantially exceeded 500 mg kg^–1. Comparing garden vegetables and soil as potential sources of Pb risk to children, it is clear that the risk is greater through ingestion of soil or dust than through ingestion of garden vegetables grown on the soil. Urban dwellers should obtain soil metal analyses before selecting garden locations to reduce Pb risk to their children.     

上海市蔬菜地土壤硝态氮状况研究

以上海市郊不同管理方式下菜地表层土壤采样测定土壤硝态氮含量为基础,并以水稻土等土壤作为对照,以期了解上海蔬菜地土壤硝态氮的现状,为菜地的合理施肥提出科学依据。结果表明,由于管理方式不同,土壤的硝态氮的NO3--N质量分数差异明显。大棚蔬菜地土壤中NO3--N明显高于其它其他用地管理方式下的土壤,依次为:w(大棚蔬菜地)>w(露天蔬菜地)>w(传统自留地),而且土壤硝态氮的积累是全剖面性的,而非仅在表层,如在80~100cm土层,大棚土壤硝态氮也为农田的好几倍。而且,大棚蔬菜地土壤盐渍化明显,主要特点之一是硝态氮积累,盐分高的土壤一般硝态氮也高。此外,长期大量的N肥投入引起了土壤酸化。土壤pH与土壤NO3--N质量分数呈线性负相关,经统计检验相关性达极显著水平。     

岷江流域不同土地利用方式下紫色土有机碳储量特征

以岷江中下游流域紫色土为研究对象,按流域分上中下游区段3个抽样层采样,研究不同土地利用方式下紫色土有机碳储量特征,为紫色土退化评估及地力维护提供参考.结果显示,紫色土有机碳总量以林地(14.151g/kg)显著高于果园地(9.458g/kg)、菜园地(8.542g/kg)、草坡地(7.875g/kg),以玉米地(6.226g/kg)最低.水溶性有机碳含量呈现林地>果园地>菜园地>草坡地>玉米地趋势.同时,流域上、中、下游紫色土有机碳总量总体上差异显著,且以上游区段紫色土有机碳总量最高.流域中下游紫色土有机碳总量变化较大,其中,林地以下游高于中游,果园及草坡地以中游高于下游.菜园地、玉米地在3个区段上差异未达显著水平.岷江流域紫色土有机碳储量总体特征表现上游最高,中下游变化复杂,下游略高于中游区域.图1表4参10     

博罗县下村农场土壤养分概况

本文探讨了博罗县下村农场土壤养分含量概况，为今后长期试验研究提供基本理论依据。分析结果表明：下村场土镶有机质含量低，土壤酸性强，不利于土壤肥力的发挥，土壤全量养分Ｎ、Ｐ、Ｋ含量不平衡，速效养分虽然有些较高以至很丰富，但其含量范围大，有相当部分土壤仍很低，所以其供应水平亦很不平衡。而坡地赤红壤则全氮低，全磷不高，全钾则高低差异很大．至于果园土壤（即耕地），养分含量亦很不一致，相差极为悬殊，没有一定的规律性．土壤养分的高低水平，对作物的养分供应起很大的作用。由于下村场土壤养分的不均衡性，在生产管理上，应因地制宜，协调养分含量，以提高施肥效果。根据下村场土壤养分含量的特点，应增施有机肥，改良土壤，并适施石灰以改善土壤酸性，以利于作物的正常生长．     

Soil quality evolution after land use change from paddy soil to vegetable land

A survey was done in 15 typical villages, 150 soil and 86 vegetable plant samples were taken in Jiaxin prefecture of the Taihu Lake region, northern Zhejian province. Results indicate that after 15-20 years land use changed from the paddy rice-wheat (or oilseed rape) double cropping system, to a continuous vegetable land has caused soil quality dramatic change. (1) Acidification: average soil pH was 5.4; about 61% of total samples were pH < 5.5. It was 0.9 units lower than 10 years ago with same upland vegetable cultivation and was 1.2 units lower than soil pH of paddy rice-wheat (or oilseed rape) rotation. (2) Fertilizer salt accumulation: the average salt content was 0.28%, among these about 36.2% of the total samples contained more than 0.3%. (3) Nitrate N and available phosphorus (P) over accumulation: on average it was 279 mg NO3-N/kg, and 45-115 mg P/kg. Nitrate N four times higher and available P 4-10 times more than it is in present paddy rice-wheat rotation soils respectively. This has caused wide concern because of possible groundwater and well drinking water pollution by leached nitrate N and the P losses to water by runoff from vegetable lands induce surface water eutrophication.     

种植蔬菜地与裸地氧化亚氮排放差异比较研究

采用大型原状土柱试验研究了种植蔬菜地与未种植蔬菜裸地土壤氧化亚氮（N2O）排放的差异。试验结果表明,施肥但未种植蔬菜的裸地土壤N2O排放量远大于种植蔬菜地的土壤N2O排放量,裸地土壤N2O平均排放通量为193μg.m-2.h-1,而种植蔬菜后土壤N2O平均排放通量减少至60μg.m-2.h-1;相应地,裸地的N2O排放总量也要远高于种植蔬菜地的N2O排放总量。同时,低施氮量（N1,500 kg.hm-2）下裸地的N2O排放量要比高施氮量（N2,750 kg.hm-2）且种植蔬菜时裸地的N2O排放量大,如2007年10月至2008年9月试验期间,N1处理下裸地总N2O-N排放量为9.54 kg.hm-2,而N2处理（种植蔬菜）下总N2O-N排放量仅为4.21 kg.hm-2。此外,未种植蔬菜时裸地土壤N2O排放系数远大于种植蔬菜时,如N1种植蔬菜时为0.39%,但未种植蔬菜的裸地土壤排放系数为1.76%。研究说明种植作物与否对土壤N2O排放有重要影响,因此在估算农田土壤N2O排放温室气体量时,需考虑裸地的贡献能力。     

Estimated lead (Pb) exposures for a population of urban community gardeners

Urban community gardens provide affordable, locally grown, healthy foods and many other benefits. However, urban garden soils can contain lead (Pb) that may pose risks to human health. To help evaluate these risks, we measured Pb concentrations in soil, vegetables, and chicken eggs from New York City community gardens, and we asked gardeners about vegetable consumption and time spent in the garden. We then estimated Pb intakes deterministically and probabilistically for adult gardeners, children who spend time in the garden, and adult (non-gardener) household members. Most central tendency Pb intakes were below provisional total tolerable intake (PTTI) levels. High contact intakes generally exceeded PTTIs. Probabilistic estimates showed approximately 40 % of children and 10 % of gardeners exceeding PTTIs. Children’s exposure came primarily from dust ingestion and exposure to higher Pb soil between beds. Gardeners’ Pb intakes were comparable to children’s (in µg/day) but were dominated by vegetable consumption. Adult household members ate less garden-grown produce than gardeners and had the lowest Pb intakes. Our results suggest that healthy gardening practices to reduce Pb exposure in urban community gardens should focus on encouraging cultivation of lower Pb vegetables (i.e., fruits) for adult gardeners and on covering higher Pb non-bed soils accessible to young children. However, the common practice of replacement of root-zone bed soil with clean soil (e.g., in raised beds) has many benefits and should also continue to be encouraged.     

Soil Quality Evolution After Land Use Change From Paddy Soil to Vegetable Land

A survey was done in 15 typical villages, 150 soil and 86 vegetable plant samples were taken in Jiaxin prefecture of the Taihu Lake region, northern Zhejian province. Results indicate that after 15–20 years land use changed from the paddy rice–wheat (or oilseed rape) double cropping system, to a continuous vegetable land has caused soil quality dramatic change. (1) Acidification: average soil pH was 5.4; about 61% of total samples were pH < 5.5. It was 0.9 units lower than 10 years ago with same upland vegetable cultivation and was 1.2 units lower than soil pH of paddy rice–wheat (or oilseed rape) rotation. (2) Fertilizer salt accumulation: the average salt content was 0.28%, among these about 36.2% of the total samples contained more than 0.3%. (3) Nitrate N and available phosphorus (P) over accumulation: on average it was 279 mg NO₃-N/kg, and 45–115 mg P/kg. Nitrate N four times higher and available P 4–10 times more than it is in present paddy rice–wheat rotation soils respectively. This has caused wide concern because of possible groundwater and well drinking water pollution by leached nitrate N and the P losses to water by runoff from vegetable lands induce surface water eutrophication.     

不同利用方式下黄壤旱坡地磷素状况及环境影响分析

通过对贵州黄壤进行采样以及采用无界径流小区法收集地表径流,探索不同利用方式下黄壤旱坡地磷素水平及其地表径流磷浓度的差异。结果表明,不同利用方式下黄壤旱坡地中全磷和有效磷(Olsen-P)含量的大小顺序为连作烟地>烤烟-玉米轮作地>连作玉米地>林地;CaCl_2浸提磷(土壤易解吸磷)和Na0H浸提磷(藻类可利用的土壤总磷)与土壤全磷和有效磷有显著的相关性;土壤富磷化的同时,其磷素的流失风险明显地提高。连作烟地地表径流总磷(TP)和磷酸根态磷(Ortho-P)浓度明显大于连作玉米地.而林地地表径流TP浓度明显小于旱地;黄壤旱坡地地表径流中TP和Ortho-P与土壤有效磷之间存在极显著的相关性(r为0.957、0.875),因而连作烟地磷素的环境影响潜能明显高于其它旱地以及林地。     

Field studies on 32P movement and P leaching from flooded paddy soils in the region of Taihu Lake, China

Field experiments were done in two sites, Yixing and Changshu, Jiangsu province, China, to study P movement and leaching in flooded paddy soils. P movement in soil was investigated by using the KH2 32PO4 tracker method, and the amount of P leached from the soil layer in different depths was estimated by measuring P concentrations in the soil solution and saturated hydraulic conductivities in field. Determination was done about one month after P application. There was 46% and 42% of total 32P retained in the 0-5cm layer of soil in the Yixing site and in the Changshu site respectively. The 32P retained in the 25-30 cm layer was only about 1-2% of the total 32P added. Furthermore, 8.01% of 32P in the soil of Yixing site and 16.8% of 32P in the soil of Changshu site was lost from the layer 0-30 cm soil. The seasonal amounts of P leached from the top soil layer and from bottom layer are about 4.5-5.8% and 1.6-2.1% of the total P application, respectively. Changes of total P concentrations in soil solutions during rice growth showed that the fertilizer P applied before flooding of the paddy fields suffered a flash leaching loss and a slow leaching loss. We concluded that the fertilizer P could quickly move in the flooded paddy rice field and parts of it can enter into surface water and ground water. Unless the P application is well managed the risk of P loss and consequently environmental pollution exist.