Effectiveness of Chloride Compared to 3,4-Dimethylpyrazole Phosphate on Nitrification Inhibition in Soil

Microbial oxidation of ammonium to nitrate may impose dangers to ecosystem functioning through soil and atmosphere contamination with end products or intermediate gases. A wide range of chemicals can inhibit nitrification under soil and laboratory conditions. In the present study, the effectiveness of chloride compared to 3,4-dimethylpyrazole phosphate (DMPP) as a standard nitrification inhibitor was evaluated. The results showed that DMPP (especially with double concentrations) inhibited nitrification for a longer time, until the end of incubation period. Chloride in the form of ammonium chloride (NH₄Cl) or potassium chloride (KCl) also significantly inhibited nitrification compared to the control during the 7-week incubation period. This inhibition was positively correlated with applied chloride concentrations in soil. During a 5-week incubation period, the strongest concentration (500 mg/kg soil) showed more inhibition than concentrations of 250 or 100 mg/kg soil, particularly when compared to control. The results suggest that beside commercial nitrification inhibitors, chloride can significantly inhibit microbial nitrification in soil. Therefore, when chloride is not a soil problem, the chloride form of nitrogen fertilizers (e.g., ammonium chloride) could be a proper nitrogen fertilizer.     

Distribution and Availability of Zinc in Soil Fractions to Wheat on Some Alkaline Calcareous Soils

Experiments under laboratory and greenhouse conditions were conducted to investigate the response of wheat to Zn application in five loess-derived alkaline calcareous soils and to assess the contribution of Zn in various soil fractions on its uptake by plants. Zinc in soil extracted by different reagents was also determined. Total Zn ranged from 58 to 81 mg/kg. On an average 45% of total Zn in all soil fractions was associated with sand, silt and clay. Whereas silt alone held 33% of total Zn among soil fractions in the five soils. Ammonium acetate extractable and acid residual Zn (Sand, silt and clay) explained 98% of variation of Zn in plants, and 70 or 75% of Zn in the AB-DTPA extract and DTPA extract respectively. Application of 10 mg Zn/kg soil significantly (P < 0.01) increased plant shoot dry weight, Zn concentration and total Zn content in plants over control. Concentration of Zn in plants was significantly positively correlated with Zn extracted with DTPA and AB-DTPA in soils.     

Effect of Liming on the Plant Availability and Distribution of Zinc and Copper among Soil Fractions

Abstract

Information on the redistribution of applied micronutrients into different fractions as a result of lime application is important to predict plant accumulation of nutrients and to select appropriate chemical extraction procedures for evaluation of micronutrient availability. The present work was carried out to study the influence of liming on the availability and redistribution of zinc (Zn) and copper (Cu) among soil fractions. Additionally, the effect of liming was evaluated on the recovery of these micronutrients by different chemical extractants (Mehlich‐1, Mehlich‐3, and diethylenetriaminepentaacetate (DTPA), which were correlated with Zn and Cu concentrations in corn (Zea mays L.) plants and soil fractions (exchangeable, organic matter, amorphous iron oxides, and crystalline iron oxides). The results showed that Zn added to soil samples that did not receive lime was retained mainly in the exchangeable and organic matter fractions. The liming resulted in distribution of Zn into iron oxides and as a result decreased the plant accumulation of Zn. Mehlich‐3 was the most efficient extractant to predict the plant accumulation of Zn in the acid soils, whereas DTPA was the most efficient in the limed soils. The oxide crystalline fraction was the major fraction responsible for retaining Cu in the soils. However, Cu added to soil was distributed mainly into organic matter. Mehlich‐3 was the most suitable extractant for predicting the bioavailability of Cu in limed or unlimed soils.     

硝化抑制作用机理研究进展

总结了氨氧化细菌(AOB)和氨单加氧酶(AMO)的特性及氨(NH3)的催化氧化过程,综述了烷烃、烯烃、炔烃、芳烃、含硫(S)化合物、氮(N)杂环化合物和双氰胺(DCD)的硝化抑制作用机理。     

赤泥颗粒对韭菜吸收污染土壤中铅锌的抑制效应研究

采用盆栽试验方法,通过添加赤泥颗粒修复铅锌污染土壤,按照火焰原子吸收分光光度法测定不同时期种植韭菜的土壤中重金属的含量,分析赤泥颗粒对土壤中重金属的钝化行为与机理,确定赤泥颗粒对土壤修复和对韭菜生长促进最佳的添加量。结果表明,赤泥颗粒能缓释OH-,促进重金属铅、锌化学形态转化和抑制生物吸收。铅、锌污染土壤修复的最佳赤泥颗粒添加量为5%,此时,土壤中铅、锌的生物有效态含量在修复期内分别降低了41.03%、26.55%;结合铅锌污染土壤修复与韭菜生长影响,初步确定赤泥颗粒的最佳施用量为1%,此时,土壤中铅、锌的生物有效态含量在修复期内分别降低了24.81%、15.9%;赤泥颗粒对铅锌污染土壤的修复能力大小为铅〉锌。     

黄绵土铅形态与土壤酶活性关系的研究

采用添加外源铅和室内培养的方法,研究了黄绵土盆栽小青菜后土壤中铅的形态分布规律及土壤酶活性对铅污染的响应,并分析了土壤铅形态与土壤酶活性的关系。结果表明,未污染黄绵土中铅各形态的比例为：可交换态0.77%,碳酸盐结合态6.27%,铁锰氧化物结合态1.82%,有机结合态13.4%,残渣态77.74%。铅污染后黄绵土中各形态铅的浓度随着外源铅浓度的增加而极显著增加,土壤受到铅污染后,各形态铅的比例发生了显著变化,上列各形态所占比例依次为0.346%、18.464%、0.496%、46.532%、34.168%。铅污染对过氧化氢酶和碱性磷酸酶产生极显著影响（[R过氧化氢酶=0.841 1,P过氧化氢酶〈0.001,n=18;R碱性磷酸酶=-0.986 9,P碱性磷酸酶〈0.001,n=18）],二者可以作为土壤铅污染的评价指标;总铅对过氧化氢酶、碱性磷酸酶和脲酶的活性变化没有任何贡献,进一步说明不能采用总铅含量作为土壤铅污染的评价指标。在铅的各化学形态中除有机结合态外,过氧化氢酶与其余各形态铅含量均呈极显著正相关;碱性磷酸酶与各形态铅均呈极显著负相关;碳酸盐结合态对过氧化氢酶和碱性磷酸酶的直接影响最大,而且铅的其他化学形态通过碳酸盐结合态的间接影响亦最大,表明各形态铅中以碳酸盐结合态对两种酶的影响为主,该两种酶与碳酸盐结合态相结合可作为土壤铅污染评价指标。     

施磷处理对中性紫色土土壤硝化作用的影响

针对长期定位试验站长期不施化肥的低磷土壤,设置了不同水平的磷素添加共9个处理(P2O5 0~150 mg kg-1土),通过75 d的室内培养实验,探讨磷素处理对土壤硝化细菌及硝化作用的影响。结果表明,适量磷素添加显著刺激了硝化细菌生长,但高浓度磷素添加将抑制硝化细菌数量。进一步通过好氧培养法和悬液法分别测定了土壤硝化潜势,发现不同水平的磷素短期培养后,土壤硝化潜势均出现不同幅度的增加,并且均在P2O5 40~60 mg kg-1土之间最高,但磷素供应水平影响硝化作用的机制仍待进一步研究。     

冬种绿肥对水稻土硝化作用的影响

冬闲田种植绿肥是传统的水稻土培肥增产措施,但绿肥-水稻种植系统中,不同绿肥种类对硝化作用的影响规律及调控机制尚不明确.采用盆栽试验,研究了冬种紫云英、油菜、黑麦草对土壤性状及硝化作用的影响,并通过特异性细菌抑制剂(卡那霉素和大观霉素)研究了氨氧化细菌(AOB)和氨氧化古菌(AOA)对硝化作用的相对贡献.结果表明,冬种三...     

2-氯-5-氟-硝基苯对硝化抑制作用及玉米增产效应的研究

通过对实验室培养试验和田间试验结果综合分析 ,表明与硝化抑制剂 ,2 ,5 二氯硝基苯有相似结构的 2 氯 5 氟 硝基苯也具有硝化抑制作用 ,但在不同的土壤上 ,其效果存在明显差异 ,在土壤肥力高的潮土上的效果显著 ,抑制剂的施用与否可使用土壤中NO3 N的含量相差 2— 3倍。玉米以碳铵作N源 ,减少正常N肥用量 2 0 % ,施用 2 氯 5 氟 硝基苯 ,玉米产量较对照增产 12 6% ,达到极显著水平     

我国几种农田土壤硝化势的研究

对我国三种土壤类型的农田土壤剖面的硝化势进行研究 ,结果表明 ,培育 2 8天时的土壤硝化势与土壤pH值存在着极显著的正相关 ,r =0 75 0 ,土壤剖面各层土壤有机质含量与土壤硝化势也呈正相关 ,但统计没有达到极显著。说明土壤 pH和土壤有机质含量是影响硝化作用的主要因素。同时对 3种土壤上氮肥通过淋洗和反硝化损失的可能性进行了推测     

不同硝化抑制剂的复配施用对尿素转化及土壤中氮的影响

通过室外模拟田间培养试验,研究不同硝化抑制剂及其复配后的硝化抑制效果。结果表明:不同硝化抑制剂,明显抑制了NH4+-N向NO3--N的转化。硝化抑制剂1-甲胺酰基-3,5-二甲基吡唑(CMP)有明显的抑制效果,优于4氨基-1,2,4-三唑盐酸盐(ATC)、双氰胺(DCD);硝化抑制剂CMP与DCD复配的抑制效果显著,硝化抑制率为35.6%。为了结合生产实际获得最优性价比,在硝化抑制剂复配比率方面尚需进一步研究。     

Soil Organic Matter Fractions in Experimental Forested Watersheds

Recent concerns about climate change and atmospheric greenhousegas concentrations have demonstrated the importance ofunderstanding ecosystem C source/sink relationships. Soilorganic matter fractionation was carried out in three paired,forested watershed sites where one of each watershed pairrepresented a different ecosystem perturbation. Theperturbations were 8 years of experimental N amendments at theBear Brook Watershed in Maine (BBWM), a 50 year old intensewildfire and subsequent regeneration at Acadia National Park(ANP), and a 17 year old whole-tree harvest at the Weymouth PointWatershed (WPW). At each site, mineral soils were sampled byuniform depth increments. Mineral soil (< 2 mm) was separatedinto light, occluded light, and heavy density fractions byfloatation in NaI solution (1.7 g cm^-3). Mineral soil (< 2mm) was also separated into particle-size fractions of sand (2.0to 0.05 mm), silt (0.05 to 0.002 mm), and clay (< 0.002 mm) bywet sieving and centrifugation. Whole soils, and density andparticle-size fractions were analyzed for total C and N. Bothfractionation schemes showed that all soil organic matterfractions had lower C/N ratios as a result of N enrichment atBBWM. At ANP, soil organic matter fractions generally had lowerC/N associated with the wildfire and subsequent shift fromsoftwood to hardwood regeneration. Few significant whole soiland soil organic matter fraction differences were associated withthe whole-tree harvest. Within watershed pairs, both density andparticle-size fractionation techniques usually indicated similarresponses. Soil organic matter fractionation results indicatedthat there were no consistent shifts in fraction distributions inresponse to perturbation that were consistent across all pairedwatershed study sites.     

土壤中硝化抑制剂DMPP含量的气相色谱测定法

建立了一种检测土壤中吡唑类硝化抑制剂DMPP含量的气相色谱法。DMPP在NaOH溶液中可定量转化为DMP,从5种有机溶剂中选择氯仿作为DMP的萃取剂。本文采用吡啶做为内标物,内标校正因子fDMP和fDMPP分别为1.6775和3.3884。通过DB-1701气相色谱柱,氢火焰离子化检测器(FID)定量检测氯仿溶液萃取相中的DMP。本法添加回收率为97.4%～98.8%;RSD为0.70%～2.09%;土壤中DMPP的检出限为0.4mgkg-1。应用本法测定在潮棕壤中10℃、20℃和30℃时DMPP的降解半衰期分别为大于28d、14d和7d。     

盐碱草甸植被退化对土壤硝化作用强度的影响

为了解不同退化阶段盐碱草甸草原土壤硝化作用强度特征及其影响因素,采用空间代替时间的方法,以松嫩平原盐碱草甸草原植被退化过程中4种典型植物群落为对象,以未做处理为参照,设置刈割、施氮和刈割同时施氮3种处理,测定了土壤的硝化作用强度(NI)、pH值、电导率(EC)、含水量(SMC)和有效磷(OP)、硝态氮(NO^-₃-N)、铵态氮(NH+4-N)及全氮(TN)的含量。结果显示:(1)土壤NI与pH值、电导率、含水量、OP和NO^-₃-N呈极显著正相关关系(p<0.01);通过逐步回归分析的方法得出土壤NI的重要影响因子,重要影响因子对土壤NI影响强弱表现为:pH值>有效磷含量>含水量>硝态氮含量,并推断土壤硝态氮含量可作为土壤NI的一个重要表征参数。(2)未作处理时,星星草群落与碱蓬群落土壤硝化作用强度分别为13.4,13.5 mg/(kg·h),显著高于羊草群落和退化羊草群落的5.0,2.5 mg/(kg·h),刈割和施氮处理分别使星星草群落土壤NI提高96.88%,253.77%,混合处理使其提高413.70%,显著高于其他3种植物群落,由此可见,在人为刈割和施氮肥的干预下,星星草群落土壤铵态氮可能更易转变为硝态氮,氮素流失的风险也更大,因此可认为星星草群落处于盐碱草甸退化过程中的关键阶段。     

不同开垦年限白浆土土壤磷库特征

以我国三江平原地区不同开垦年限的白浆土为研究对象,采用Hedley等首次提出经Agbenin J.O.Tiessen H改进的方法对土壤磷库组成成分进行研究,即连续浸提法对土壤中不同形态磷素变化特征进行研究,结果表明:长期开垦施肥可显著增加土壤中活性无机磷(Resin-Pi和NaHCO3-Pi)和有机磷(NaHCO3-Po)的含量,NaOH-Pi随开垦年限增加含量升高,且其占总无机磷的比例随开垦年限增加而增加,开垦0 a最低(3.89%),开垦30 a后比例达到最高值(41.98%)。难溶性无机磷(1M HCl-Pi和Conc-HCl-Pi)占总无机磷的比例随开垦年限增加而降低(65.98%³0.98%),NaOH-Po是有机磷库的主要组成部分(57.91%30.98%),NaOH-Po是有机磷库的主要组成部分(57.91%⁸4.41%),开垦0 a比例最高(84.41%),开垦30 a后比例最低(57.91%)。在开垦前20 a有机磷是该地区白浆土土壤磷库的主要组成部分。     

保护性耕作对土壤有机碳组分的影响

为了探讨土壤有机碳及活性有机碳组分对不同耕作措施的响应,在黄土高原半干旱区的定西市李家堡镇进行了长期田间定位试验,采用免耕、秸秆覆盖及小麦和豌豆轮作等保护性耕作措施,对0-5 cm,5-10 cm,10-30cm 3层土壤的有机碳(SOC)、易氧化有机碳(ROC)、微生物生物量碳(MBC)的动态进行了系统的研究,结果表明,与传统耕作相比,保护性耕作的3个处理均能不同程度地提高两种轮作次序下SOC,ROC,MBC的含量,这说明保护性耕作有利于碳的固定和生态农业的健康发展,其中免耕和秸秆覆盖两部分结合效果最佳.同时,各处理土层的含碳量均随土壤深度的增加而降低.相关分析表明,ROC,MBC,ROC/SOC,MBC/SOC对不同耕作措施产生的响应与SOC基本一致,它们可以作为对土壤SOC影响的评价指标,与SOC的相关系数大小排序依次为MBCROCMBC/SOCROC/SOC,在表征土壤有机碳变化上它们比SOC更敏感,其灵敏度排序为MBCROC/SOCMBC/SOCROC,因此,在ROC,MBC,ROC/SOC,MBC/SOC等指标中,MBC更要值得重视和采用.     

草萘胺在黄泥土不同粒径微团聚体上的吸附行为

采用超声分散法提取了太湖地区黄泥土中不同粒径的团聚体颗粒,用批次吸附试验的方法研究了除草剂草萘胺在各团聚体颗粒组上的吸附特点。结果表明,不同粒径微团聚体的草萘胺吸附等温线均可用Freundlich方程定量描述,Kf值介于5.56~11.40之间,以粒径<0.002mm和2.00~0.25mm两个粒组吸附容量最大,粒径0.25~0.02mm和0.02~0.002mm两个粒组吸附容量较小。在各团聚体粒组中对土壤吸附草萘胺相对贡献率最大的是粒径<0.002mm粒组。由于颗粒细小的微团聚体更易于在土壤-水环境中迁移,因此,草萘胺在黄泥土上的这种分布特点对环境的潜在影响不容忽视。     

Degradation of AM Nitrification Inhibitor in Soil of Subtropical Region

The aim of the study was to evaluate the degradation and persistence of 2-amino 4-chloro 6-methyl pyrimidine (AM), nitrification inhibitor at 1 and 2 µg g^?1 application rates in soil. The extraction of AM was done by QuEChER’s (Quick, Easy. Cheap. Rugged and Safe) method and the quantitative analysis by high-performance liquid chromatography (HPLC). AM decreased with time at both the levels of application with the decline being faster in the beginning up to 7 d. Dissipation of AM occurred in a single phase with the persistence data fitting well to the first-order kinetics. Half-lives of AM were determined to be 14.33 and 16.7 d at 1 and 2 µg g^–1 levels application rates. Since AM remains effective for an adequate period of time, it can be used for increasing efficiency of nitrogenous fertilizers in rice–wheat cropping systems as well as a safeguard for controlling environmental pollution in subtropical soils.     

Changes in Fractions of Iron,Manganese, Copper,and Zinc in Soil under Continuous Cropping for More Than Three Decades

The effect of continuous cropping with maize and wheat on soil characteristics and various forms of micronutrient cations in an Incetisol over the years was studied in an ongoing long‐term experiment in New Delhi, India. The soil samples collected in the years of 1993, 1995, 1997, 1999, 2001, 2003, and 2004 were analyzed for different fractions of iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) by following a sequential extraction procedure. The pH, electrical conductivity (EC), and calcium carbonate (CaCO₃) content of the soil varied from 8.28 to 8.53, 0.40 to 0.43 dSm^?1, and 0.92 to 1.05%, respectively. Organic carbon content ranged from 0.38 in the control to 0.67% in 100% NPK + farmyard manure (FYM). Diethylenetriaminepentaacetic acid (DTPA)–extractable Fe and Mn (but not Zn and Cu) in soil declined from their respective initial (1971) values as a result of intensive cropping for more than three decades. It also resulted in a decrease in the concentrations of all the four metallic cations bound to organic matter, in addition to Fe and Zn, associated with carbonates in all the treatments in surface soil.     

Effect of Soil Organic Matter on Adsorption of Nitrification Inhibitor Nitrapyrin in Black Soil

ABSTRACT

Experiments were conducted to study the adsorption kinetics and isothermal adsorption mechanism of nitrification inhibitor nitrapyrin onto the black soil of northeastern China. The nitrapyrin adsorption kinetics of the black soil were fitted with a quasi-second-order kinetics equation before and after organic matter removal (R² ≥ 0.8320, p < .05). The adsorption isotherm was obtained by the Langmuir equation (R² ≥ 0.9400, p < .05). Isothermal adsorption requires less energy and is a spontaneous endothermic reaction with an L-type isothermal curve (n > 1), dominated by surface physical adsorption. With the decrease of organic matter content in black soil, the adsorption mechanism of nitrapyin changed from distribution mechanism to surface adsorption. The black soil’s organic matter content exhibited a quadratic relation with the maximum adsorption capacity and adsorption constant (Kf) at the different temperatures, reaching significant levels (R² ≥ 0.6484, p < .05).