施用有机肥料对土壤胡敏酸结构特征的影响──胡敏酸的光学性质

本工作通过田间试验和模拟试验研究了施用有机物料对棕壤、草甸土和水稻土中胡敏酸光学性质的影响。结果表明，施用有机物料后使土壤胡敏酸的吸光值和相对色度下降，色调系数升高，甚至发生类型改变。还使胡敏酸紫外２８５ｎｍ和红外２９２０ｃｍ＾－１吸收增强，１７２０ｃｍ＾－１和萤光强度减弱，激发光谱最大强度波长紫移。说明胡敏酸的分子结构变得脂族化，简单化和年轻化。两种有机物料相比，玉米秸杆对胡敏酸的木质素特征作用     

苜蓿培肥对灰漠土养分及胡敏酸特性的影响

通过荒地和苜蓿地土壤养分、土壤胡敏酸热解特性和红外光谱特征的比较，研究了灰漠土上种植苜蓿培肥对土壤养分和土壤有机质特性的影响。结果表明，种植苜蓿可以增加土壤有机质、全N和碱解N的含量，但速效磷和速效钾含量则下降，土壤pH不变。苜蓿地胡敏酸的脂肪族侧链较多，胡敏酸较年轻，而荒地胡敏酸侧链较少，胡敏酸相对较老。苜蓿地胡敏酸的脂族性强于荒地。种植苜蓿培肥后土壤胡敏酸变得简单化和年轻化。     

不同施肥处理土壤胡敏酸及其级分 与 Fe2+的络合特征 Ⅰ.胡敏酸原样与 Fe2+的络合特征

采用 17年不同施肥处理 (无肥、化肥、秸秆、厩肥 )土耕层土样 ,在对土壤胡敏酸性质研究的基础上 ,着重研究不同施肥处理土壤胡敏酸与Fe2+的络合特征 ,揭示络合作用与胡敏酸性质以及环境条件的关系。结果表明 ,不同施肥处理土壤胡敏酸与Fe2+的络合能力不同。和无肥处理相比 ,化肥处理胡敏酸的络合能力加强 ,logk值 (络合稳定常数 )增大 ,有机肥处理则使胡敏酸的络合能力下降 ,logk值减小。logk值大小与胡敏酸的羧基、酚羟基以及总酸度有关。pH值、温度、离子强度是影响络合稳定常数大小的环境因素 ,pH值由 4到 7,各处理胡敏酸的logk值增大 ,络合配位数也有增加趋势。温度升高 ,离子强度增大 ,logk值降低。胡敏酸与Fe2+络合反应是一个自发的放热反应 ,络合后整个体系的有序性增强 ,熵值减小。     

稻草腐解过程中形成胡敏酸的组成和结构研究

通过稻草腐解实验,采用化学分析方法,研究了稻草腐解过程中土壤胡敏酸的化学特征的动态变化,旨在丰富农作物秸秆还田过程中的胡敏酸化学组成、性质与结构变化的特征。在试验培养条件下,施用稻草后土壤的有机碳含量提高了31.71%,腐殖质含量增加了51.93%,都在90d时达到最大值。施用稻草45d时的PQ值(HA在HS中所占的比例)明显降低,在90d和135d时的PQ值与45d时变化不大。施用稻草后土壤胡敏酸的色调系数(ΔlogK)逐渐减少,相对色度(RF)值迅速增大,胡敏酸的氧化程度和芳构化程度增强。胡敏酸的元素组成以碳为主,含量在52%左右,其次为氧。H/C的比值逐渐降低,O/C的比值不断增大。羧基和酚羟基为主要的酸性基团。羧基含量先降低,后随着腐解的进行,其含量不断升高;酚羟基的含量变化与羧基的含量变化趋势相反;羰基含量逐渐增加。施用稻草会引起紫色水稻土胡敏酸化学组成和结构的变化。     

傅立叶变换红外光谱法表征玉米秆茬培肥土壤胡敏酸的变化

土壤腐殖质是土壤肥力的重要物质基础,在土壤有机碳库中占有相当大的比重,腐殖质可分成三个组分:胡敏酸(HA,不溶于酸),富里酸(FA,溶于酸)[1]和胡敏素(HM)。其中胡敏酸是土壤腐殖质中的活跃成分,其存在形态、分子组成、理化性质的变化对土壤的肥力特征都会产生巨大影响[2-3]。玉米植株残体作为有机肥的一个重要组成部分,施入土壤后必然对土壤HA的数量、组成、结构及存在形式产生影响,并使其理化性质发生改变,从而起到改善土壤环境和培肥土壤的作用。研究证明,玉米植株残体施入土壤后,土壤胡敏酸的理化性质得到显著的改善[4-5]。张晋京等…     

施用有机肥料对胡敏酸结构特征的影响─—胡敏酸的1H-核磁共振波谱

通过在棕壤，草甸土和水稻土上进行田间试验和模拟试验表明，施用有机肥料一般使胡敏酸的脂族Ｈ的相对含量增加，聚亚甲基链长，变短，芳香Ｈ相对含量和由之计算的芳香度下降，从而导致ＨＡ中脂族Ａｌｉ－Ｈ与Ａｒ－Ｈ的比值增加，即发生了脂族化。     

秸秆深还对土壤腐殖质组成和胡敏酸结构特征的影响

以辽宁省阜新县试验基地培肥3年的草甸褐土为研究对象,设CK(不施秸秆)和CS(秸秆深还施用量为24 000 kg hm-2)2个处理,每个处理随机选取3个采样点,采集深度为0～20 cm和20～40 cm。采用腐殖质组成修改法提取水溶性物质(WSS)、胡敏酸(HA)、富里酸(FA)和胡敏素(Hu),研究秸秆深还对土壤腐殖质各组分含量的影响,并提取土壤胡敏酸(HA)固体样品进行结构表征。研究表明:秸秆深还更有助于表层土壤及其各腐殖质组分WSS、HA、FA和Hu有机碳含量的积累,分别较CK增加了33.11%、26.39%、11.09%、9.197%和18.55%,亚表层土壤WSS有机碳含量变化不显著,但HA和Hu的含碳量降低;表层和亚表层土壤PQ值的变化不显著;表层和亚表层土壤HA,缩合度变大,分子结构变复杂,芳香结构增加,热稳定性相对提高,亚表层土壤HA脂族结构稳定性增强。     

胡敏酸的氮素形态分布及其未知态氮的部分鉴定

作者比较研究了水稻土和旱地土壤胡敏酸(和新形成胡敏酸)的氮素形态分布,并对胡敏酸水解液中铵态氮的来源、水解性未知态氮中非α-氨基酸态氮的含量和非水解性氮中N—苯氧基氨基酸的含量进行了研究。供试的土壤胡敏酸有3组,同组胡敏酸提取自发育于同一母质且地块毗邻的水田和旱地(或自然土壤)的表土。新形成胡敏酸也分为3组,同组胡敏酸提取自pH条件相同但水分状况不同的稻草腐解产物。     

有机物料施用下原生盐碱土胡敏酸结构特征

为研究不同有机物料对原生盐碱土胡敏酸官能团组成的影响,以吉林省大安市原生盐碱地为研究对象,设置空白处理(CK)、颗粒状秸秆处理(KL)、正常玉米秸秆处理(JG)、牧草处理(MC)和羊粪处理(YF),通过红外光谱与主成分分析(Principal component analysis,PCA)相结合,研究不同有机物料施用下土壤胡敏酸红外光谱特征。结果表明,有机物料各处理与CK处理相比增加了土壤胡敏酸中脂肪碳和芳香碳的相对含量,减少了羧基碳的含量。除KL处理外,其他处理均增加了土壤胡敏酸中氨基化合物的相对含量。同时有机物料的施用增加了土壤胡敏酸的脂族碳/羧基碳和脂族碳/芳香碳比值,表征有机物料的施用使得土壤胡敏酸结构缩合度和氧化度下降,脂族性增强,芳香性降低,胡敏酸结构趋于脂族化、简单化、年轻化。对比两种秸秆处理,发现KL处理更有利于土壤新形成结构年轻化、简单化、脂族性强的胡敏酸分子。根据PCA结果,有机物料的施用是土壤中脂族性碳、芳香族碳以及氨基化合物的主要来源之一,为探讨胡敏酸官能团的来源提供依据。通过红外光谱结合PCA,发现了土壤胡敏酸官能团组成对有机物料的不同响应,为研究有机物料的施用对土壤胡敏酸性质的影响机制提供理论依据。     

有机物料对白土土壤胡敏酸结构特征的影响

【目的】研究有机物料施入对白土土壤的腐殖质含量组成和胡敏酸(HA)结构特征的影响,为明确不同腐殖质组分对土壤肥力的影响提供理论依据。【方法】供试土壤为江苏省溧阳市南渡镇"白土改良大田示范试验核心区"的南方中低产水稻土(白土)。试验设秸秆还田(ST)、施有机肥(OM)和对照(CK,不施有机物)3个处理,培肥3年。同时采集试验田周围相邻的江苏省耕地质量监测点(2007~2013年)的每年施化肥(LAF)和长期不施肥(NF)的两种处理土壤进行比对研究。分别测定土壤的基本理化性质及其腐殖质含量的组成,并提取土壤胡敏酸(HA)固体样品利用红外光谱和元素分析来进行结构表征。【结果】秸秆还田和施有机肥处理的有机碳、全氮含量明显高于对照;与对照相比,施有机物料土壤HA的E4/E6比值增加,且秸秆还田施有机肥对照。红外光谱显示,试验区域和耕地监测点的不同处理土壤HA均在1650 cm-1处(酰胺I带)和1550 cm-1处(1500~1580 cm-1酰胺II带伸缩振动)有特征吸收。施有机肥和秸秆还田处理土壤HA的2920/1720、2920/1650比值显著大于对照。在元素组成上,OM、ST处理的土壤腐殖质(HA)中C、H、N的含量比均高于CK,相对长期施化肥(LAF)和不施肥(NF)的土壤有明显提高,而氧元素的含量呈降低的趋势;OM和ST处理土壤HA的[H]/[C]和[O]/[C]原子数比均低于CK;与LAF和NF处理相比,试验区域各处理土壤腐殖质的[H]/[C]和[O]/[C]原子数比均有明显降低。【结论】有机物料施入土壤后可增加土壤有机碳含量,改善土壤理化性质,提高作物产量和品质,且施入土壤的有机物料可转化为新的腐殖质,降低土壤的腐殖化程度。土壤腐殖质(HA)的红外光谱分析说明,白土土壤HA具有明显的酰胺类化合物特征。有机物料施入后使得土壤脂族性增强,羧基量减少,芳香度降低;秸秆还田和施有机肥处理与对照相比,土壤HA的[H]/[C]和[O]/[C]比均有下降的趋势,且HA的氮素含量明显增加,这显示有机物料施入后白土土壤腐殖质发生"脱水"过程,同时也反映了白土土壤腐殖质形成的特征。     

非饱和土壤水分运动与热力学函数关系初探

在不同的温度条件下,研究了土壤水势对水分运动的影响,结果表明,在同一温度条件下,提高土壤水势可增加土壤非饱和导水率,呈现黄绵土＞lou土,在相同的土壤含水量条件下,增加温度可提高土壤非饱和导水率,其导水率温度效应值（dk/kt)lou土＞黄绵土。土壤含水量一定时,随着相对偏摩尔自由能亦[△（△-/G）]和相对偏摩尔焓变[△（△-/H）]增大,土壤非饱和导水率也增大,并且呈出黄绵土＞lou土,拟合得出的相对偏摩尔自由能变[△（△-/G）]和相对偏摩尔焓变[△（△-/H）]与土壤非饱和导水率方程,具有较好的适应性。     

腐殖酸的数均分子量测定

腐殖酸是广泛存在于土壤、污泥、泥炭、煤和水域中的天然大分子电解质,它对土壤肥力、植物生长、环境中元素的迁移和富集有重要作用,近廿年来日益为人们所重视,但其化学结构和分子量的确切范围目前尚不甚清楚。迄今为止,尚没有一种测定各种腐殖酸分子量的良好方法^[11]。     

Adsorption strength of zinc for soil humus

Soil humus plays a significant role in the cation exchange of a soil. YOSHIDA (1) showed that, as a general rule, divalent ions such as calcium and magnesium were adsorbed more strongly onto humus than monovalent ions such as ammonium and potassium in an ion-exchange reaction. He did not, however, describe the behavior of heavy metal ions. BREMNER et al. (2) first suggested that soil organic matter forms complexes with polyvalent cations. HIMES and BARBER (3) found that soil organic matter reacts with divalent metal ions in a manner similar to the chelation reaction. Reviews of the soil organic matter-metal complex have been written by BREMNER et al. (2) and KAWAGUCHI, MATSUO and KYUMA (4).     

Evaluation of readily available nonexchangeable potassium in soil by sequential extractions with 0.01 molar hydrochloric acid

Nonexchangeable potassium (K-ne), i.e. 1 M NH₄OAc-nonexchangeable K, often contributes significantly to plant nutrition. However conventional extraction methods often extract much more K-ne than plants even after intensive cropping, suggesting the difficulty in evaluating the amount of readily available soil K-ne. In this study, we used a milder extraction method (0.01 M HCl method) to examine its applicability to evaluate the amount of readily available K-ne in soil. In the first experiment, the concentration of K-ne in twenty surface soils sampled from agricultural fields in Japan and K-bearing minerals was determined by the 0.01 M HCl method, i.e. sequential extraction with 0.01 M HCl over a period of 10 d after removal of exchangeable K, and by conventional methods. The average percentage of the soil K-ne extracted by the 0.01 M HCl method amounted to 0.66% of the total K amount, and was much lower than that by a single extraction with 1 M HNO₃ (2.0%) or with 0.2 M sodium tetraphenylboron for 2 d (22%). In the second experiment, the amount of K-ne removed by chemical extractions was compared with that of K-ne removed by maize plants grown for 29 d in five of the above soils. The amount of the K-ne evaluated by the 0.01 M HCl method gave the highest correlation (p < 0.05) with that of the K-ne utilized by plants among the extraction methods applied. The amount of soil K-ne extracted by the 0.01 M Hel method could therefore become a suitable index of the amount of readily available K-ne in soil. Extraction of K-ne in soils after maize planting further indicated that plants had removed K-ne more intensively than the 0.01 < HCl method probably only from the rhizosphere, although a high correlation was observed between the amount of K-ne removed by the 0.01 M Hel method and that by plants. This implies that the estimation of the amount of K-ne utilized by plants requires not only soil chemical analysis but also the evaluation of the percentage of the soil volume where the plant-induced release of K-ne actually occurs.     

Occurrence of laminar opaline silica in some Oregon Andosols

Laminar opaline silica was first found in the 0.2 to 5 μ fraction and most abundant in the 0.4 to 2 μ fractions of young Japanese Andosols by Shoji and Masui (1969a, b). It was noted that the A horizon of a profile tends to be relatively rich in opaline silica whereas the B or C horizon, in allophane (Shoji and Masui, 1972a, b). They (I972a) distinguished four types of opaline silica particles such as circular, elliptical, rectangular, and rhombic, of which the circular and elliptical types predominate. It has been suggested that the formation of opaline silica is favored by a plentiful supply of soluble silica in the early weathering stage of Andosols, the supersaturation of silica by surface evaporation of soil solution, and the suppression of aluminum activity in the soil solution by the accumulation of soil organic matter (Shoji and Masui, 1972b; Wada and Harward, 1974). The purpose of the present short communication is to describe the occurrence of laminar opaline silica particles in some Oregon Andosols, U.S.A.     

Method of extracting organic acid from flooded soil

Investigations on the extraction and determination of organic acids in flooded soil have been reported by TAKAI (1) and TAKIJIMA (2). TAKAI applied water to extract acids from soil and determined them by BULLEN's method (3). However, TAKIJIMA reported that organic acid could not be completely extracted by TAKAI's procedure, especially in soil with a high organic matter content such as muck and peaty soils, and proposed an extraction procedure with 0.5 N sulfuric acid. He also discussed the absorption of acids by soil.