低分子量有机酸对土壤磷释放动力学的影响

模拟植物在缺磷条件下,根系所分泌的有机酸种类和数量,用流动法研究了柠檬酸,苹果酸,草酸和酒石酸对土壤磷释放的影响。结果表明：有机酸能明显促进土壤中磷的释放,不同有机酸对石灰性土壤活化能力大小的次序为草酸≥柠檬酸〉苹果酸〉酒石酸;而对酸性土壤磷的释放量与Ｆｅ＋Ａｌ释放量之间呈极 相关,有机酸活化土壤磷能力大小的次序为柠檬酸〉草酸〉酒石酸〉苹果酸。     

pH和磷的交互作用对稳定化土壤砷释放的影响

以3种含Fe材料稳定化土壤(FeSO_4、FeS和Fe~0稳定化土壤)为研究对象,研究了不同pH和P的交互作用对As释放量的影响及其作用机理。结果表明,在pH=3条件下,随着时间的延长能够促进释放的As重新趋于稳定化,而pH=11时3种稳定化土壤中As的释放量显著增加,144 h后分别约为pH=3时的10.5、16和10倍。添加P时,在3种pH条件下都促进了稳定化土壤中As的释放,尤其在酸性条件下,相对于无P体系As的释放量增加最为明显。FeSO_4稳定化土壤中As的释放特征能用Elovich方程较好地描述,而双常数方程拟合FeS和Fe~0稳定化土壤效果更优。在pH=3条件下,3种稳定化土壤中As的释放量与Ca、Mg、Mn的溶出量呈(极)显著相关,而pH=11时FeSO_4和FeS稳定化土壤中As的释放量与SO_4~(2–)的溶出量呈(极)显著相关,表明在酸性条件下,稳定化土壤As的释放主要受Ca、Mg、Mn氧化物结合态As溶解的影响,而碱性条件下,FeSO_4和FeS稳定化土壤中As的释放可能与硫化物的溶解有关。     

不同土壤磷的固定特征及磷释放量和释放率的研究

通过加入不同浓度的P(水土比为 2 0∶1 )并利用连续提取法 ,对三种土壤P的固定特征以及磷的释放进行了研究。结果表明 ,红壤对P的固定能力高于潮土 ,而潮土高于水稻土 ,在加入P量为 2 97gkg- 1土壤的条件下 ,三种土壤对P的固定量分别为 2 84gkg- 1、2 5 3gkg- 1和 2 0 8gkg- 1。三种土壤对P的固定率则随着加入P量的增加而降低。在P的释放研究中 ,随着提取次数的增加 ,P的释放量减少 ,并在提取 8次后 ,以后各次P的释放量不发生显著变化。三种土壤中 ,水稻土P的最大释放量 (1 2 4 0 7mgkg- 1)显著高于红壤 (60 46mgkg- 1)和潮土 (1 9 74mgkg- 1) ,水稻土P的总释放量 (1 6次 )也大于红壤和潮土 ,三种土壤P的总释放量分别为 2 0 6 0 2 (1 98gkg- 1土壤P处理 )和 2 71 91mgkg- 1(2 97gkg- 1土壤P处理 )、1 0 0 48和2 60 5 3mgkg- 1、1 1 6 0 6和 1 3 1 91mgkg- 1。三种土壤P的释放率随着提取次数的增加而增加 ,并逐渐达到稳定。水稻土的释放率显著高于红壤和潮土。水稻土和潮土中 ,1 98gkg- 1土壤P处理的土壤P的释放率高于2 97gkg- 1土壤P处理的土壤 ,红壤则相反     

苹果酸对温室土壤磷释放与吸附的影响

试验研究了不同浓度苹果酸处理对温室土壤磷吸附和释放的影响,并运用DPS数据分析系统建立了土壤磷释放和吸附与苹果酸浓度之间相关的数学模型。结果表明:(1)随着苹果酸用量增加,土壤释放磷量也逐渐增加。二者之间的关系可以用Peal-Reed等7种不同类型的数学模型拟合;(2)供试土壤对磷的吸附较好地符合Langmu ir方程式;苹果酸显著降低了土壤对磷的吸附,随着苹果酸浓度的增加,土壤对磷的最大吸附量和最大缓冲容量都呈现下降趋势。     

淹水土壤磷释放机理研究进展

磷是水体富营养化的主要控制因素,以农业磷为主的非点源污染通常是水体富营养化的主要来源。在许多农业地区,尤其在季节性洪水淹没的条件下,变化的环境因素导致农业土壤释放到水中的磷加剧。本文主要以影响磷释放吸附的因素为角度,综述了国内外淹水条件下土壤磷释放机理的研究进展,并指出了目前研究存在的问题,提出了建议。     

东平湖表层沉积物中磷的吸附容量及潜在释放风险分析

利用沉积物磷吸附指数（PSI）和磷吸附饱和度（DPS）研究了东平湖表层沉积物的磷吸附容量,并讨论了沉积物中磷的潜在释放风险。结果表明,表层沉积物的磷吸附指数变化范围为30.3～45.2[mg P·（100g）-1]·（μmol·L-1）-1,表现出从湖心、湖东向湖北、湖南逐渐增大的扇形特征;而磷吸附饱和度变化范围为6.5%～24.1%,与磷吸附指数变化趋势恰好相反。磷吸附指数与沉积物中草酸铵提取的铁（FeOX）含量呈极显著正相关,与草酸铵提取的铁铝总量呈显著正相关,磷吸附饱和度与沉积物中草酸铵提取的磷（POX）含量呈显著正相关。此外,磷释放风险指数（ERI）变化范围为14.9%～67.5%,表明东平湖表层沉积物中磷释放诱发富营养化的风险处于高度风险范围。     

施用粪肥对农田土壤磷素累积和饱和度增加速率的影响

针对施用粪肥导致的我国集约化种养区域农田土壤磷素高量累积和高环境风险问题,利用长期定位试验定量分析了施用粪肥对农田土壤磷素累积和磷饱和度（DPS, degree of P saturation）增加速率（每年1 kg P·hm-2磷素盈余所导致的土壤磷素含量或DPS变化量）的影响。结果表明：连续22年过量磷素投入明显提高了土壤磷素含量和DPS,0~20 cm土层土壤磷素累积、DPS增加与磷素盈余均存在明显的线性相关性。与单施化肥相比,施用粪肥对土壤全磷的累积速率影响不大,但是明显提高了土壤Olsen-P累积和DPS增加速率。施用粪肥下,每年1 kg P·hm-2的磷盈余所导致的0~20 cm土层土壤Olsen-P、CaCl2-P累积和DPS增加量分别为0.071 mg P·kg-1（r=0.608, P=0.029）、0.003 mg P·kg-1（r=0.528, P=0.066）和0.036%（r=0.863,P=0.002）,分别为不施粪肥的3.3、6.0倍和1.2倍。土壤DPS变化与磷含量变化之间也存在明显的线性关系,0~20 cm土层土壤每年全磷、Olsen-P和CaCl2-P含量增加1 mg P·kg-1所导致的土壤DPS增加值分别为0.13%、0.42%和7.78%。20~40 cm土层土壤磷素累积、DPS增加与磷素盈余之间的线性相关性均较差,但与0~20 cm土层相比,施用粪肥和不施粪肥之间累积速率的差异性有增大的趋势,说明施用粪肥促进了磷素向下层土壤的移动。施用粪肥加速了土壤有效磷累积和DPS增加,进而提高了土壤中磷素损失风险,合理施用粪肥是控制集约化种养区域农田磷面源污染的关键。     

磷素供应对三种蔬菜磷吸收分配的影响

采用营养液培养的方法,研究不同磷浓度对小白菜、樱桃萝卜和菜豆的干重以及磷素吸收的影响。结果表明,3种蔬菜各器官的干重和吸磷总量与溶液磷浓度呈抛物线形关系,高磷浓度显著抑制了3种蔬菜根部的生长,与对照相比,小白菜、樱桃萝卜和菜豆在P浓度2.0 mmol/L处理的根部干重分别降低了20.0%、26.3%和20.0%,差异达到显著水平。随溶液磷浓度的增加,3种蔬菜的根冠比逐渐降低,蔬菜各器官(除豆荚外)的全磷含量显著增加。樱桃萝卜、小白菜和菜豆各处理茎叶的全磷含量比对照分别增加了47.5%~94.9%、45.6%~87.7%和44.6%~70.8%。高磷浓度下蔬菜奢侈吸收磷养分。菜豆各处理豆荚的全磷含量无显著差异,且随溶液磷浓度提高,豆荚吸磷量占总吸磷量的比重逐渐降低。     

干湿交替条件下土壤磷释放及其与土壤性质的关系

通过四川瀑布沟水电站消落区典型土壤磷释放室内模拟试验,研究淹水及干湿交替条件下消落区土壤性质变化情况以及土壤性质与磷释放之间的关系,以期为预防水库水体富营养化,水库消落区合理利用与科学制定管理对策提供参考。结果表明：淹水能够提高土壤活性氧化铁（Feox）含量,淹水风干后土壤Feox含量降低至淹水前的水平;淹水后Feox变化幅度为：旱地〉水田〉果园,紫色土〉冲积土。土壤磷吸持饱和度（DPS）与无定形铁铝氧化物Alox密切相关;土壤最大吸磷量（Qm）淹水时最高增加至2 758.01 mg/kg,土壤淹水后Qm、土壤最大缓冲容量（MBC）、土壤吸磷指数（PSI）值升高;淹水能够明显提高土壤的磷素缓冲容量、土壤的最大缓冲能力和吸附能力、土壤磷的保持率,其原因也是与淹水后土壤无定形铁铝氧化物含量大幅度增加有关;通过主成分分析,土壤磷释放能力主要与土壤磷水平和土壤吸磷能力有关,且主要指标包括土壤有机质含量（OM）、土壤有效磷含量（Olsen-P）、土壤磷保持率（f）、土壤最大吸磷量（Qm）、土壤活性氧化铁（Feox）、土壤活性氧化铝（Alox）等,说明四川省瀑布沟水电站消落区土壤存在较大的磷释放风险。     

改良剂降低富磷蔬菜地土壤磷和氮流失的作用

为了解不同改良剂对土壤中磷和氮的稳定作用,进行田间试验研究在施用量为2.5t/hm2时氢氧化铝、石灰石粉、石膏、氯化钙和粉煤灰5种改良剂对蔬菜地地表径流中磷和氮浓度的影响。结果表明,改良剂施用可明显降低土壤有效磷和水溶性磷含量,轻微增加土壤中NH4+-N含量,但对土壤中NO3--N影响不大。施用改良剂可显著降低蔬菜地地表径流中总磷、溶解态磷、颗粒态磷和NH4+-N的浓度,增加水溶性有机氮浓度,但对水溶性总氮和NO3--N浓度影响不明显。与对照比较,施用氢氧化铝、石灰石粉、石膏、氯化钙和粉煤灰5种改良剂的地表径流中总磷浓度下降比例平均分别为13.68%,35.54%,38.72%,43.77%和45.02%,溶解态磷浓度下降比例平均分别为16.05%,32.42%,48.75%,55.38%和38.98%;NH4+-N浓度下降比例平均分别为24.21%,37.84%,11.31%,10.08%和55.56%。总体上,施用氯化钙和粉煤灰降低地表径流中磷浓度的效果好于其他改良剂。     

北京地区菜园土壤磷素积累的剖面特征及对环境的潜在影响

Profile characteristics of accumulated P in 10 representative soils of vegetable fields in suburban districts of Beijing were investigated. Bioavailability of the accumuIated P and its potential effect on the environment were studied in a greenhouse pot experiment and a soil column experiment. The results showed that theconcentration of Olsen-P in the 0-20 cm soil samples of the vegetable fields ranged from 22.1 to 358.0 mg kg^-1, which was 2 to 10 times higher than that of the crop fields in the suburbs of Beijing. Most of theexcessive phosphorus was accumulated in the topsoils. The longer the soils cultivated with vegetables, thehigher the soil total P, Olsen-P and organic matter concentration. Accumulated P in the soils from vegetablefields had higher bioavailability. Application of phosphorus fertilizer could not increase the dry weights ofcucumbers, Chinese cabbage, and rape seedlings continuously planted. The soil column study showed high P concentration (> 0.6 mg L^-1) in the leachates from the columns of the vegetable field soils with high accumulated P, which has a potential effect on the groundwater and natural water quality.     

A simplified risk assessment for losses of dissolved reactive phosphorus through drainage pipes from agricultural soils

Abstract

Soil tests with extractions are commonly used for risk assessments of phosphorus (P) leaching. Procedures for routine analysis of crop-available soil P by extraction with acid ammonium lactate (P-AL) have been used for nearly 50 years in Sweden, Norway and several East European countries. Aluminium and iron (Al-AL and Fe-AL) were determined in the same extract for 40 well known clayey, loamy or sandy soils from the Swedish long-term studies. Average outcome was 16.8 and 6.0% for the two elements related to extraction with chelating ammonium oxalate (Al-AO and Fe-AO) and concentrations had a correlation coefficient of 0.947 and 0.891, respectively, when the two extraction agents were compared. On average, P-AL determination using inductive coupled plasma (ICP) resulted in 19% higher soil P concentrations compared to analysis using a colorimetric method based on non-calcareous and calcareous soils from the southern counties in the Swedish soil survey, represented mainly by sandy loam soils. Degree of P saturation on a molar basis in the AL extract (DPS-AL) was determined for 22 Nordic observation fields with drained clayey, loamy and sandy soils. Results were used together with long-term flow-weighed concentration of dissolved reactive P (DRP) concentration in drainage water. These parameters were correlated (r=0.918, p=0.000) and could be fitted to a linear regression model (R²=84.3). In addition, two fields with unusually high DPS-AL values could clearly be identified as those with lowest P sorption index and highest DRP concentrations in drainage water. This demonstrates DPS-AL to have the potential as an environmental risk indicator for Swedish acid soils. A set of 230 non-calcareous soils in the southern counties of Sweden from the Swedish soil survey indicated that 3% of the soils had a high DPS-AL in the topsoil or subsoil, from which high DPS leaching probably occurs.     

Phosphorus accumulation and leaching risk of greenhouse vegetable soils in Southeast China

Over-fertilization has caused significant phosphorus(P) accumulation in Chinese greenhouse vegetable production(GVP) soils. This study, for the first time, quantified profile P accumulation directly from soil P measurements, as well as subsoil P immobilization, in three alkaline coarse-textured GVP soil profiles with 5(S5), 15(S15), and 30(S30) years of cultivation in Tongshan, Southeast China. For each profile, soil samples were collected at depths of 0–10(topsoil), 10–20, 20–40, 40–60, 60–80, and 80–100 cm. Phosphorus accumulation was estimated from the difference in P contents between topsoil and parent material(60–100 cm subsoil). Phosphorus mobility was assessed from measurements of water-soluble P concentration(PSol). Finally, P sorption isotherms were produced using a batch sorption experiment and fitted using a modified Langmuir model. High total P contents of 1 980(S5), 3 190(S15), and 2 330(S30) mg kg~(-1) were measured in the topsoils versus lower total P content of approximately 600 mg kg~(-1) in the 80–100 cm subsoils. Likewise, topsoil PSol values were very high, varying from 6.4 to 17.0 mg L~(-1). The estimated annual P accumulations in the topsoils were 397(S5), 212(S15), and 78(S30) kg ha~(-1) year~(-1). Sorption isotherms demonstrated the dominance of P desorption in highly P-saturated topsoils, whereas the amount of adsorbed P increased in the 80–100 cm subsoils with slightly larger P adsorption capacity. The total P adsorption capacity of the 80–100 cm subsoils at a solution P concentration of0.5 mg L~(-1) was 15.7(S5), 8.7(S15), and 6.5(S30) kg ha~(-1), demonstrating that subsoils were unable to secure P concentrations in leaching water below 0.5 mg L~(-1) because of their insufficient P-binding capacity.     

Influence of soil phosphorus status,texture, pH and metal content on the efficacy of amendments to pig slurry in reducing phosphorus losses

Cost‐effective strategies for using chemically amended organic fertilizers need to be developed to minimize nutrient losses in surface and groundwater. Coupling specific soil physical and chemical characteristics with amendment type could increase their effectiveness. This study investigated how water‐extractable phosphorus (P) was affected by chemical amendments added to pig slurry and how this effect varied with soil properties. A 3‐month incubation study was conducted on 18 different mineral soils, stored at 10 °C and 75% humidity and treated with unamended and amended slurry which was incorporated at a rate equivalent to 19 kg total P (TP )/ha. The amendments examined were commercial‐grade liquid alum, applied at a rate of 0.88:1 [Al:TP ], and commercial‐grade liquid poly‐aluminium chloride (PAC ), applied at a rate of 0.72:1 [Al:TP ]. These amendments were previously identified by the authors as being effective in reducing incidental losses of P. The efficacy of the amendments varied with the soil test P, the degree of P saturation (DPS ) and the Mehlich aluminium, iron and calcium, but not soil texture. Chemical amendments were most effective in soils with DPS over approximately 20%. Due to their high cost, the incorporation of amendments into existing management practices can only be justified as part of a holistic management plan where soils have high DPS .     

蔬菜安全生产管理及质量追溯系统设计与实现

可追溯体系作为控制农产品质量安全的有效方法日益受到世界各国重视.以蔬菜初级产品为研究对象,从信息技术的角度构建了一个以实现质量追溯为目的的蔬菜安全生产管理及质量追溯系统,设计了系统主要功能实现的流程,探讨了关键技术,综合采用数据库技术、网络技术、产品编码技术和生产预警技术,以.net为平台,开发了安全生产管理及质量追溯系统;系统实现了生产企业端的产前管理、产中管理、产后管理、.生产预警、统计分析、条码打印、短信发送和消费者端的质量追溯、质量反馈、健康指导等功能.该系统在北京市多家企业应用,运行结果表明:使用该系统提高了企业生产管理水平,增强了消费者的农产品安全意识.从信息技术的角度,提出了一套从蔬菜初级产品生产直接到消费的管理和追溯模式,为实现全程追溯打下了基础.     

结实期土壤水势对水稻籽粒品质及其粒间差异的影响

为探讨结实期土壤水分对水稻籽粒品质的影响, 以中熟籼稻“扬稻6 号”和中熟粳稻“扬粳9538”为材料, 在盆栽条件下, 研究了不同土壤水势(0 kPa、-15 kPa、-30 kPa、-45 kPa)对水稻籽粒品质的影响, 并进一步探讨了不同粒位间的差异。结果表明, 结实期土壤水分对稻米籽粒品质有较大影响, 且影响程度因品种、粒位不同而异。与对照(0 kPa)相比, 土壤轻度胁迫(土壤水势在-15~-30 kPa 之间)籽粒的精米率、整精米率和崩解值增加, 垩白度和消碱值降低; 不同粒位间比较, 土壤轻度胁迫对水稻穗上二次枝梗或同一枝梗上较迟开花籽粒的影响较大。随土壤水势进一步降低稻米品质变劣。在0 ~ -45 kPa 范围内, 随土壤水势的降低,粗蛋白含量和胶稠度增加。灌浆期土壤轻度落干(土壤水势在-15 ~-30 kPa)有利于稻米品质的改善。     

水土保持的水环境质量效应研究进展

 随着点源污染逐步得到有效的控制,非点源污染对经济社会可持续发展的危害更加突显。根据水土流失与非点源污染的联动关系,界定了水土保持水环境质量效应的概念;将国内外与水土保持和水土流失有关的非点源污染研究归纳为3个方面:污染物运移的影响因子与机制分析、非点源污染模型的研发和非点源污染控制措施研究。对其研究进展分别进行了介绍和评述,并展望了发展趋势。     

控释尿素在水及不同类型土壤中的养分释放特征

试验采用静水培养和土壤培养研究控释尿素的养分释放特征,比较其在不同类型土壤和静水中的养分释放差异, 探讨土壤类型对其养分释放的影响。结果表明,试验选用的控释尿素在250.5℃静水条件下, 初期养分溶出率为1.7%, 28 d养分累积释放率为59.2%, 释放期为50 d, 控释尿素在土壤培养的前50 d, 水稻土中的氮素表观释放率显著低于潮土和黄棕壤中, 50~140 d在水稻土中的氮素表观释放率最高,140 d之后在三种类型土壤中的氮素表观释放率无显著差异。控释尿素在不同类型土壤中的养分表观释放率均与在静水中的显著相关。     

Tillage and amendment effects on soil carbon and nitrogen mineralization and phosphorus release

The influence of tillage and nutrient amendment management on nutrient cycling processes in soil have substantial implications for environmentally sound practices regarding their use. The effects of 2 years of tillage and soil amendment regimes on the concentrations of soil organic matter variables (carbon (C), nitrogen (N) and phosphorus (P)) and C and N mineralization and P release were determined for a Dothan fine-sandy loam soil in southeastern Alabama. Tillage systems investigated were strip (or conservation) and conventional tillage with various soil nutrient amendments that included no amendment, mineral fertilizer, and poultry waste (broiler litter). Surface soil (0–10 cm depth increment) organic matter variables were determined for all tillage/amendment combinations. Carbon and N mineralization and P release were determined on surface soils for each field treatment combination in a long-term laboratory incubation. Soil organic P concentration was 60% greater in soils that had been conventionally tilled, as compared with strip-tilled, both prior to and following laboratory incubation. Carbon and N mineralization results reflected the effects of prior tillage amendment regime, where soils maintained under strip-till/broiler litter mineralized the greatest amount of C and N. Determination of relative N mineralization indicated that strip tillage had promoted a more readily mineralizable pool of N (6.1%) than with conventional till (4.2%); broiler litter amendments had a larger labile N fraction (6.7%) than was found in soils receiving either mineral fertilizer (4.1%) or no amendment (4.7%). Tillage also affected P release measured during the incubation study, where approximately 20% more inorganic P was released from strip-tilled soils than from those maintained under conventional tillage. Greater P release was observed for amended soils as compared with soils where no amendment was applied. Results from this study indicate that relatively short-term tillage and amendment management can significantly impact C, N, and P transformations and transfers within soil organic matter of a southeastern US soil.