Soil Acidity Changes in Bulk Soil and Maize Rhizosphere in Response to Nitrogen Fertilization

The capacity of nitrogen (N) fertilizers to acidify the soil is regulated principally by the rate and N source. Nitrogen fertilizers undergo hydrolysis and nitrification in soil, resulting in the release of free hydrogen (H⁺) ions. Simultaneously, ammonium (NH₄ ⁺) absorption by roots strongly acidifies the rhizosphere, whereas absorption of nitrate (NO₃ ^?) slightly alkalinizes it. The rhizosphere effects on soil acidity and plant growth in conjunction with N rate are not clearly known. To assess the impact of these multiple factors, changes in the acidity of a Typic Argiudol soil, fertilized with two N sources (urea and UAN) at two rates (equivalent to 100 and 200 kg N ha^?1), were studied in a greenhouse experiment using maize as the experimental plant. Soil pH (measured in a soil–water slurry), total acidity, exchangeable acidity, and exchangeable aluminum (Al) were measured in rhizospheric and bulk soil. Plant biomass and foliar area (FA) were also measured at the V₆ stage. Nitrogen fertilization significantly reduce the pH in the bulk soil by 0.3 and 0.5 units for low and high rates respectively. Changes in the rhizosphere (the “rhizospheric effect”) resulted in a significant increase in soil pH, from 5.9 to 6.2. The rhizospheric effect × N source interaction significantly increased exchangeable acidity in the rhizosphere relative to bulk soil, particularly when UAN was added at a low rate. Only total acidity was significantly increased by the fertilizer application rate. In spite of the bulk soil acidification, no significant differences in exchangeable aluminum were detected. Aerial biomass and FA were significantly increased by the higher N rate, but N source had no effect on them. Although changes in acidity were observed, root biomass was not significantly affected.     

Soil Acidification Induced by Ammonium Sulphate Addition in a Norway Spruce Forest in Southwest Sweden

The contributions of different acidifying processes to the total protonload (TPL) of the soil in control plots (C) and ammonium sulphate treatedplots (NS) were studied in a Norway spruce stand in Southwest Sweden during 1988–1998. The annual deposition of inorganic nitrogen and sulphate was on average 18 kg N and 20 kg S ha^-1. In addition the NS treated plots received 100 kg N and 114 kg S ha^-1 annually. The amounts of nutrients added to the ecosystem by wet and dry deposition and the leaching at 50 cm depth were calculated. The net atmosphericproton load, the proton load by nitrogen transformations in the soil, the sulphate sorption/desorption in the soil and the excess base cation accumulation in biomass were calculated. There was no leaching of inorganic nitrogen from control plots during the study period. The net atmospheric proton deposition, originating from sulphuric and nitric acid deposition, was the main contributor to TPL in control plots. The addition of ammonium sulphate increased the leaching of ammonium, nitrate, sulphate, magnesium and calcium but not of potassium. The TPL in NS plots was about ten times that in control plots. The nitrogen transformation processes were the main contributors to TPL to NS soil, in the beginning by ammonium uptake and later also by nitrification. The pH decreased by 0.4 units in the mineral soil. The between-year variation in TPL during the eleven year period in C plots (200–1500 mol_c ha^-1 yr^-1) and in NS plots (1000–13000 mol_c ha^-1 yr^-1) was mainly dependent on the sorption or release of sulphate. Both in C and NS, the TPL was buffered mainly by dissolving solid aluminium compounds, most probably some Al(OH)₃ phase.     

硝化抑制剂双氰胺对褐土中尿素转化的影响

采用好气土壤培养法,研究北京地区典型褐土中添加不同浓度水平硝化抑制剂双氰胺（Dicyandiamide,DCD）条件下土壤中铵态氮、硝态氮变化规律。结果表明,44d培养期内,DCD施用显著提高土壤中NH4＋-N浓度,降低NO3--N浓度,1%、2%、3%、4%和5%DCD用量处理条件土壤NH4＋-N平均浓度比单施尿素对照处理分别升高29.50%、71.84%、99.73%、98.90%和139.69%,NO3--N平均浓度降低3.71%、15.61%、21.07%、33.57%和37.90%。综合反映NO3--N和NH4＋-N变化规律的土壤表观硝化率指标变化结果表明,1%、2%、3%、4%和5%DCD用量处理比对照分别降低12.18%、35.35%、44.82%、48.18%和59.93%;1%、2%、3%和4%DCD处理达到平衡时间分别延迟7d、14d、14d和21d,5%DCD处理表观硝化率一直较低,直到培养结束仍呈升高的趋势;2%、3%、4%DCD处理表观硝化率升高速率显著下降（分别降低39.32%、40.00%和52.27%）。综合考虑作物氮素需求规律、环境效应和使用经济效益,4%DCD用量效应最佳,具有较好的土壤铵氧化抑制效果,有助于提高氮素利用率,减少环境流失。     

铵钾施用次序和比例对油菜生长和氮钾养分吸收的影响

通过油菜盆栽试验研究了铵(NH4 )钾(K )离子施用次序和比例对这两种离子在土壤中的交互作用及其对油菜生长和N、K养分吸收的影响.结果表明:当NH4 、K 摩尔比为1:1时,先NH4 后K ,油菜的生物产量和N、K养分吸收量均较低,该结果与后施入的K 促进了先施入的NIL4 的固定,降低了土壤NH4 -N含量有关.而当NH4 、K 质量比为1:1(其摩尔比约为3:1)时,施用次序对该土壤油菜的生长和养分吸收影响不大,这也说明了合适的N、K比例对作物生长的重要性.     

施用蚯蚓粪对杨树苗根际土壤生物学特征的影响

通过盆栽试验,研究了CF(单施化肥)、VC(蚯蚓粪)和VC+CF(蚯蚓粪和化肥各提供50%的氮)处理对一年生欧美I-107杨根际土壤微生物数量、酶活性、根系建造水平及理化性状的影响。结果表明,VC+CF处理有利于协调土壤C/N比,并且化肥的施入补充了土壤中氮的消耗,从而明显提高了根际土壤中微生物数量及脲酶、过氧化氢酶、多酚氧化酶和蔗糖酶活性,其中细菌数量分别比CK,CF和VC处理提高165.99%,67.34%和31.73%,蔗糖酶活性分别提高90.37%,45.31%和32.34%。施用蚯蚓粪有利于杨树苗细根的生长,但对地上部的增长速度显著快于地下部。此外,VC+CF处理使根际土壤pH值明显降低,显著增加了根际土壤中养分离子的有效性。与VC+CF处理相比,VC处理对根际土壤生物学特征的影响较小。因此,蚯蚓粪与化肥配施更好地改善了杨树苗根际区域的微生态环境。     

玉米根际和非根际土壤细菌微多样性与土壤有机碳矿化的关系

[目的]运用高级别分类学分辨率揭示玉米根际和非根际土壤中细菌群落微多样性,并探讨微多样性与土壤有机碳矿化的关系,从更精细的分类学分辨率水平上为玉米根际土壤中微生物驱动的碳循环提供理论依据。[方法]以西北农林科技大学曹新庄试验农场为依托,采取田间生长条件下玉米根际和非根际两种土壤类型。利用高通量测序技术,比较OTUs和ASVs两种分类学分辨率水平上玉米根际和非根际土壤中的细菌群落结构,揭示细菌群落的微多样性。同时通过培养试验检测根际和非根际土壤的有机碳矿化特性。[结果]通过比较OTUs和ASVs两种分类学分辨率水平上的细菌群落,OTUs和ASVs两种方式显示出相似的细菌群落结构。在玉米根际和非根际土壤类型中,ASVs在更高分类学分辨率水平上描绘细菌群落组成,同时揭示了普遍存在于OTUs内的不同菌株或生态型。此外,两种不同生长策略(r-策略和K-策略)细菌物种的相对丰度差异是导致根际和非根际土壤细菌群落结构不同的主要因素。培养试验表明,根际土壤有机碳矿化量显著高于非根际土壤。3 a的连续采样分析结果表明,根系是田间成熟玉米根际和非根际土壤理化性质差异的主要因素而受时间(2019—2021年...     

14C-吡虫啉在苗期油菜中的吸收、转运与分布特性

为深入了解吡虫啉在植物体内的行为规律,本研究以14C-吡虫啉为研究对象,采用种衣剂拌种法,设低药种比(4.8和5.4 g ? kg-1)以及高药种比(6.0和7.2 g·kg-1)处理,利用同位素示踪技术及现代仪器分析技术,探讨了吡虫啉在苗期甘蓝型油菜中的动态吸收变化和转运分布规律.结果表明,药种比6.0 g·kg-1...     

盐碱胁迫对香樟幼苗根际土壤酶活性的影响

以2年生盆栽香樟幼苗为材料,分别施用0、50、100、200 mmol/L的Na2CO3和Na HCO3(1︰1)混合溶液,研究盐碱胁迫对香樟幼苗根际土壤酶活性的影响。结果表明:随着盐碱胁迫时间的延长,各处理土壤p H不断上升,且随盐碱处理浓度越高,p H越大;对照的脲酶活性呈不断上升的趋势,盐碱胁迫处理的脲酶活性呈先升后降的趋势,盐碱处理浓度越高,土壤脲酶活性越小;过氧化氢酶活性呈不断上升的趋势,盐碱处理浓度越高,过氧化氢酶活性越大;土壤蔗糖酶活性呈先升后降的趋势,盐碱处理浓度越高,土壤蔗糖酶活性越小;轻度(0~50 mmol/L)盐碱胁迫程度促进碱性磷酸酶活性,而重度盐碱(50~200 mmol/L)胁迫抑制碱性磷酸酶活性;0 mmol/L处理的蛋白酶活性不断上升,而盐碱胁迫抑制蛋白酶活性。盐碱胁迫影响了土壤中有效养分的转化。     

硫酸法钛石膏作为土壤调理剂在油菜上的施用效果研究

为研究钛白粉生产过程中经无害化处理的副产品钛石膏作为土壤调理剂的施用效果及安全性,试验对供试钛石膏通过成分鉴定—土柱淋溶—盆栽种植的方式,研究了钛石膏和钛石膏淋溶液中的有害元素含量以及钛石膏与土壤不同比例掺混后对油菜生长、产量和功能叶光合速率影响。结果表明:钛石膏主要成分为CaSO_4和Fe_2O_3,固体中的重金属含量均符合国家安全标准。钛石膏淋溶液中含有较少量的Ca~(2+)、Mg~(2+),不含其他有害物质,施用后不会随雨水和灌溉污染土壤和地下水。随着钛石膏添加比例的增加,油菜产量呈先增高后降低的趋势,过量的钛石膏施用会抑制油菜的生长。钛石膏与土壤按照1∶4体积比混合施用后效果最好,与常规土壤栽培方式相比,油菜出苗20天后功能叶蒸腾速率提高了11.86%;出苗30天后功能叶SPAD值增加了4.33%,收获时油菜株高提高了12.97%,产量增加了14.08%。相关性分析显示,油菜产量(y)与钛石膏添加比例(x)的关系为y=0.0001x~3-0.0212x~2+0.6966x+41.815(R~2=0.999 4),综合考虑函数及其他因素,在实际生产中若每公顷施用300t的钛石膏能起到最佳增产效果。     

Selenium Speciation and Distribution Characteristics in the Rhizosphere Soil of Rice (Oryza sativa L.) Seedlings

A five-step sequential extraction procedure was used for the fractionation of selenium (Se) in rhizosphere and nonrhizosphere soils with rice (Oryza sativa L.) seedlings. Results showed that in rhizosphere soils without the addition of Se, the soluble Se (Sol-Se), exchangeable Se and Se bound to carbonates (Exc-Se), Se bound to organic-sulfide matter and elemental Se (OM-Se), and total Se contents were significantly greater than those in nonrhizosphere soils, whereas the residual Se (Res-Se) was less than that in the nonrhizosphere soils. After the addition of Se, the Sol-Se and OM-Se contents in the rhizosphere soils were still evidently greater than those in nonrhizosphere soils, but the Exc-Se was significantly less in rhizosphere soils than in nonrhizosphere soils. Our overall results suggest that the Se bioavailability in rice rhizosphere soils is greater than that in nonrhizosphere soils. Selenium bioavailability in the rhizosphere soil is not correlated with Se accumulation in rice seedlings.     

长期不同施肥下小麦离子吸收对土壤酸化贡献能力的比较

农业生产中长期不合理施肥导致土壤严重酸化,除了硝化作用和硝酸盐淋溶,作物对阳离子吸收是另一个重要的土壤酸度来源。本研究基于湖南祁阳红壤实验站农田25年长期定位试验研究了长期不同施肥下小麦阴阳离子吸收对土壤酸化贡献能力的变化。结果表明:长期施用化学氮肥显著降低土壤pH,影响小麦生物量,而施用有机肥可缓解土壤酸化,提高小麦生物量;单位面积土壤中小麦吸收阴阳离子对酸化的潜在贡献能力,即小麦产生的总质子量的大小顺序为:有机肥处理(M)氮磷钾配施有机肥处理(NPKM)磷钾肥处理(PK)氮磷钾肥处理(NPK)不施肥处理(CK)氮磷肥处理(NP)氮钾肥处理(NK)。相关性分析显示,小麦产生的总质子量与土壤pH、有效磷含量和地上部总生物量均呈显著正相关,而土壤pH和有效磷含量均与小麦地上部生物量呈显著正相关。因此,长期施肥的农田土壤中,随着酸化程度的加深,作物通过阴阳离子吸收对土壤酸化的贡献能力减弱,主要原因在于低土壤pH和有效磷含量限制了作物的生长,降低了作物的生物量。     

Rhizosphere Phosphorus Solubility and Plant Uptake as Affected by Crop in a Clay Soil from the Central Plateau Region of Haiti

Phosphorus (P) is commonly a limiting nutrient affecting crop yields in tropical cultivated systems, and a high P-sorption capacity in many of these soils can decrease the effectiveness of fertilizer use. Smallholder farmers, such as those in rural Haiti who do not have sufficient access to P fertilizers, may benefit from crops that are efficient at scavenging for P. To evaluate commonly grown and potentially useful plants for this purpose, a pot study was conducted in a controlled-environment chamber set to approximate ambient May–June conditions in Haiti's Central Plateau with seven treatments (six legume and one grass species) using soil from an Ustalf taken in the region. Velvet bean (Mucuna pruriens [L.] DC) produced the largest amount of biomass, though no difference in P uptake among treatments was observed. Phosphorus uptake and rhizosphere P were positively correlated, indicating plants with a larger capacity to solubilize P took up more P.     

酸雨对黄棕壤的致酸作用与对小麦幼苗膜脂过氧化水平的影响

通过模拟酸雨淋洗土壤,造成了土壤酸化和盐基流失。将小麦幼苗栽培于由酸雨致酸的土壤上,导致小麦幼苗的膜脂过氧化水平提高。其中致酸土壤对根系膜脂过氧化水平的影响大于对叶片膜脂过氧化水平的影响。     

黄河三角洲刺槐根际与非根际细菌结构及多样性

为精确分析黄河三角洲刺槐根际与非根际土壤细菌群落定殖情况,本研究采用高通量测序方法对刺槐根际与非根际土壤细菌结构及多样性进行了研究。研究表明,根际土壤细菌共有36门214属,非根际土壤细菌共有33门153属。变形菌门(Proteobacteria)、放线菌门(Actinobacteria)、酸杆菌门(Acidobacteria)细菌丰度超过15%,是根际与非根际土壤中的优势菌落。根际与非根际土壤中酸杆菌门、硝化螺旋菌门(Nitrospirae)丰度差异显著。根际土壤中红游动菌属(Rhodoplanes)、溶杆菌属(Lysobacter)、热单胞菌属(Thermomonas)、链霉菌属(Streptomyces)及非根际土壤中红游动菌属、溶杆菌属、链霉菌属、Kaistobacter细菌丰度超过4%。根际土壤中固氮菌丰度显著高于非根际土壤,解磷、解钾细菌丰度差异不显著。根际与非根际土壤细菌Chao丰富度分别为2 054、2 376,差异显著。根际与非根际土壤细菌之间的权重(Weighted Unifrac)距离在0.12~0.25之间。综上所述,黄河三角洲刺槐根际与非根际土壤细菌结构具有一定差异,多样性差异显著。     

Kinetic Characteristics of Nitrate Uptake by Wheat and Rape and Their Determination

15－day old seedlings of wheat and rape were grown in a series of solutions with different concentrations of KNO3 for a definite period of time.The changes in NO3^- concentration of the solutions were determined by the double ion-selective electrode method,and then the amount of NO3^- taken up by the plants was estimated and values of Km and Imax of the Michealis-Mentan equation were calculated.Results show that both the method and conditions of determination affected the values of Km and Imax.For example,the Km value was appreciably reduced when the volume of culture solution was increased or when the duration of nutrient uptake was shortened;the Km value obtained with short-term depletion method was higher than that obtained with long-term one.Similar Variations were found for the values of Imax.There was a considerable difference in the characteristics of uptake kinetics between wheat and rape when determined under the same conditions of determination.The isotherm of NO3^- uptake by wheat could be separated into saturated and unsaturated parts,and when the concentration of NO3^- exceeded 180μM,the relationship between the rate of NO3^- uptake and NO3^- concentration tended to be linear.However,the isotherm of NO3^- uptake by rape was found to fit the Michealis-Menten equation and no linear relationship could be found.     

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。     

鸡粪与化肥配施对杨树根际土壤生物学特征及养分吸收的影响

通过盆栽试验研究鸡粪有机肥(M)与化肥(N)配施对杨树根际土壤的微生物数量、酶活性及养分吸收的影响。结果表明:与单施化肥相比,鸡粪有机肥与化肥配施可不同程度提高根际土壤中的微生物数量,以30%M+70%N处理效果最显著,其中细菌数量比CK,100%N,10%M+90%N和50%M+50%N处理分别提高了108.21%,32.36%,22.09%和10.44%;配施鸡粪有机肥可不同程度增强土壤脲酶、过氧化氢酶、多酚氧化酶和蔗糖酶活性。30%M+70%N处理的酶活性显著高于其他4个处理;此外,鸡粪有机肥与化肥配施可显著提高根系的总吸收面积、活跃吸收面积和氮素利用率。其中30%M+70%N处理的氮素利用率为61.38%,分别比100%N,10%M+90%N和50%M+50%N处理提高了53.52%,26.53%和23.33%。与30%M+70%N处理相比,10%M+90%N和50%M+50%N处理对杨树根际土壤特征改善和养分吸收促进作用有所降低。综合分析认为,鸡粪有机肥与化肥以3∶7比例配施对杨树的根际区域生态环境改善和养分吸收作用效果最佳。     

Metal Concentrations in Aquatic Macrophytes as Influenced by Soil and Acidification

Bioavailability of metals to aquatic plants is dependent on many factors including ambient metal concentration, pH of soil or water, concentration of ligands, competition with other metals for binding sites, and mode of exposure. Plants may be exposed to metals through water, air, or soil, depending on growth form. This paper examines the influence of soil type under two regimens of water acidification on metal uptake by four species of aquatic macrophytes: smartweed (Polygonum sagittatum), burreed (Sparganium americanum), pondweed (Potamogeton diversifolius), and bladderwort (Utricularia vulgaris) in constructed, experimentally acidified wetlands. Soil types consisted of a comparatively high-metal clay or a lower-metal sandy loam. Each pond was either acidified to pH ca. 4.8–5.3 or allowed to remain circumneutral. Metal concentrations tended to be higher in the submerged bladderwort and pondweed than in the emergent burreed and smartweed. Soils were important to plant metal concentrations in all species, but especially in the emergents. Acidification influenced plant concentrations of some metals and was especially important in the submerged pondweed. Bioaccumulation of metals occurred for Mn, B, Sr, Ba, and Zn, compared to soil concentrations.     

电动模拟土壤酸化及其交换性离子组成变化

土壤酸化及其环境效应研究是土壤环境领域的重要内容。自行设计了模拟土壤酸化的电动装置,该装置由直流电源、反应槽、石墨电极组成,并采用四种不同类型土壤,研究了电动模拟土壤酸化后土壤pH、交换性酸和交换性阳离子组成的变化。实验结果显示,经电动处理后土壤pH发生明显变化,土壤pH由阳极到阴极逐渐升高,pH变幅为水稻土燥红土红壤赤红壤,水稻土的pH变化比红壤更为明显;土壤交换性H+和Al~(3+)含量在阳极附近最高,交换性Al~(3+)占交换性酸总量达65%以上;交换性Ca~(2+)、Mg~(2+)、K~+和Na~+表现出离阳极越远,含量越大的规律,其中交换性Ca~(2+)和Mg~(2+)在模拟酸化后含量变化较大,而交换性K~+和Na~+的变化幅度相对较小。结果表明,电动处理可快速获得不同pH梯度的土壤样品,并模拟了土壤酸化过程中的阳离子迁移过程,是模拟土壤酸化及其效应研究的有效方法。