土壤硝化作用过程中亚硝态氮的累积研究

在实验室条件下比较了９种土壤硝化过程中ＮＯ２＾－的累积能力和ＮＯ２＾－在不同土壤中的稳定性,并在３种代表性土壤上检测了ＮＯ２＾－累积的动态变化。结果表明,红壤和黄棕壤在所有施氨（ＮＨ４＾＋－Ｎ）水平下均未出现ＮＯ２＾－的累积;但砂姜黑土、潮土、滨海盐士、潮棕壤、褐土、灌漠土和灰钙土等均出现不同程度的ＮＯ２＾－累积,且随着施ＮＨ４＾＋－Ｎ水平提高而增加ＮＯ３＾－在红壤和黄棕壤中的累积与施ＮＨ４＾＋－Ｎ水平无关,但在其它７种ｐＨ大于７的土壤中的累积受到浓度ＮＨ４＾＋的抑制。此外,试验还表明,ＮＯ２＾－在红壤和黄棕壤中不稳定,但在其它７种土壤中相当稳定。土壤硝化过程中产生ＮＯ２＾－累积的问题应引起重视。     

HGMS技术与NaOH溶液浓缩土壤铁锰氧化物的效果比较

以我国中南地区几种土壤和土壤锰结核为材料，比较了高梯度磁分选仪与５ｍｏｌ．ｌ＾－１ＮａＯＨ溶液对土壤铁锰氧化物的浓缩效果。结果表明：（１）以１：１型高岭石为主的土样，经５ｍｏｌ．Ｌ＾－１ＮａＯＨ溶液处理后，其氧化铁浓缩倍数高于ＨＧＭＳ处理后的样品，以２：１型层状酸盐矿物为主的土壤浓缩倍数则相反。（２）ＨＧＭＳ处理浓缩土样锰结核中的锰氧化物，其浓缩倍数比５ｍｏｌ．Ｌ＾－１ＮａＯＨ溶液处理的低；但前者     

土垫旱耕人为土地球化学特征

研究了汾渭盆地的土壤旱耕人为土地球化学状态与有关影响因素。１．土垫旱耕人为土受施土粪堆垫作用改变了成土方向与过程，也改变了土壤地球化学特征。２．土垫旱耕人为土在成土过程受淋溶淀积、生物迁移富集，蒸发等作用，但被Ｃａ＾＋＋、Ｍｇ＾＋＋等离子饱和，使土壤呈偏碱性。３．土垫旱耕人为土不同亚类在成土过程中因生态环境的差异，其土壤地球化学特征稍有差异。     

砖红壤和黄棕壤Zn^2＋吸附特性的研究

测定了黄棕壤和砖红壤在不同浓度,不同ｐＨ下的总吸附Ｚｎ＾２＋及不同浓度下的专性吸附Ｚｎ＾２＋和交换吸附Ｚｎ＾２＋,结果表明,２种土壤３种吸附Ｚｎ＾２＋浓度增加而增大,两者关系较好地符合Ｌａｎｇｍｕｉｒ吸附方程,Ｚｎ＾２＋吸附量随ｐＨ升高而增加呈Ｓ形,Ｚｎ＾２＋分配系数的对数与ｐＨ呈极显著的线性正相关,吸附一个Ｚｎ＾２＋所释放Ｈ＾＋的平均数,砖红壤（１．２８）大于黄棕壤（１．０６）,但黄棕壤总吸附Ｚ     

滇桂地区变性土的发生特性和系统分类研究

本文研究了我国西南地区变性土的形成条件和发育程度，并结合世界主要分类系统进行了分类研究。结果表明，相对于地带性土壤而言，变性土风化成土作用较弱，发育程度较低，土壤中元素的淋溶迁移及相对富集程度也远低于地带性土壤。由于粘粒含量尤其是粘粒矿物组成的差异，变性土表现出极高的膨胀潜势。通过研究，本文还对我国土壤系统分类中变性土土钢、亚纲、土类等的划分标准和依据及变性土性土的确立等提出了见解。     

盐渍土盐分指标及其与化学组成的关系

用一元回归方法统计了分析了南皮县涝洼盐荒地开发区盐化土壤的盐分测定数据间的相关性。混合型土壤，全盐量０．１－１．５％范围，１：５土水比土壤浸提液电导率Ｅ与全盐有显著的直线正相关关系；不同Ｃｌ＾－／ＳＯ＾２－３比率的土壤中，同样存在显著的相关性；盐分组成不同，回归系数有所不同。     

恒电荷土壤和可变电荷土壤动电性质的研究 Ⅱ.阴离子吸附和pH的影响

本工作研究了阴离子吸附和ＰＨ对恒电荷土壤（黄棕壤和黑土）和可变电荷土壤（砖红壤）动电性质的影响。结果表明,砖红壤吸附不同阴离子后的ζ电位随ＰＨ升高由正电位移至负电位,在ζ电位－ＰＨ曲线上均有一个等电点（ＩＥＰ）在ＰＨ３．５～８之间,相同ＰＨ升高由正电红壤的ζ电位随吸附阴离子的负移顺序是ＨＰＯ４＾２－〉Ｆ＾－〉ＳＯ４＾２－〉Ｃｌ＾－〉ＮＯ３＾－。作为恒电荷土壤的黄棕壤和黑土,在不同电解发质溶液中的ε     

塿土不同粒级组分K~ 吸附研究

塿土各粒级Ｋ十吸附特征有很大区别。在一定平衡液浓度下，颗粒越细，土壤固相吸附量越大，不同粒级固相吸附量大小顺序是：（＜０．１μｍ）＞（＜１μｍ）＞（１－２μｍ）＞（２－５μｍ），不同粒级土壤有效阳离子交换量也具有相同的变化规律。混合样中不同粒级组分对吸附的贡献可用吸附贡献率表示，■土各粒级饱和吸附贡献率大小顺序为：（＜１μｍ）＞（１－２μｍ）＞（＞５μｍ）＞（２－５μｍ），其中粘粒部分的饱和吸附贡献率为８５％左右。在供试混合土样中＜１μｍ粒级吸附贡献率随平衡液浓度增大呈幂函数形式增大，相反，１～２μｍ、２－５μｍ粒级吸附贡献率随平衡液浓度增大则呈幂函数形式减小。实验证明混合样中不同粒级Ｋ＋吸附存在交互作用，吸附交互作用大小可用吸附交互作用系数表征，＜１μｍ和１－２μｍ之间存在吸附负交互作用，且随平衡液浓度增大而增强。＜１μｍ和２－５μｍ之间存在吸附正交互作用，且随平衡液浓度增大而减弱。论述了建立土壤多粒级组分吸附方程的必要性，提出了多粒级组分吸附方程：     

黄土性土壤K+吸附、解吸动力学研究

采用连续液流法研究了５种黄土性土壤吸附、解吸Ｋ＾＋的动力学性质。结果表明：（１）供试土壤Ｋ＾＋吸附、解吸反应分别在１６－２４及２６－６０ｍｉｎ达到平衡。吸附平衡时间及平衡吸附量与ＣＥＣ及粘粒含量有关。（２）平衡前不同时段的吸附解吸速度及吸附解吸率与反应时间ｌｎｔ间存在极显著的线性关系。其中反应速度直线和解吸率直线的斜率、初始反应速度及初始解吸率均与ＣＥＣ及粘粒含量密切相关。（３）一级反应方程和Ｅｌ     

氢醌在土壤水稻系统中的分布、降解和累积

用＾１４Ｃ－氢醌和＾１５Ｎ－尿素为标踪剂，通过棕壤盆栽试验，研究了氢醌在土壤中分布，存在形态及迁移机制。氢醌的残留量随土壤垂直深度的增加而增多，平均土壤残留量为０．０４１ｍｇ／ｋｇ土。由于土壤理化和生化作用，约有１３％的氢醌分解成ＣＯ２和水。残留于土壤的＾１４Ｃ，４９％进入土壤主子有机化合物，不能再被溶剂所提取。实验测定了水稻对氢醌的吸收，分配和代射，糙米和茎叶中氢醌的含量分别为０．０７ｍｇ／ｋｇ     

Base cation,aluminum, and phosphorus release potential in Danish forest soils

Long‐term nutrient supply in forest ecosystems is due to the dissolution of primary and secondary minerals in soils. The potential of nutrient release in 19 forest soils in a cool humid climate was examined. The soil profiles are classified as Alfisols (10), Spodosols (2), Entisols (4), Ultisols (1), and Mollisols (2), thus covering a gradient in soil fertility. Short‐term and long‐term release of calcium, magnesium, potassium, phosphorus, and aluminum was evaluated by a batch extraction using dilute nitric acid (0.1 M) for 2 hours, followed by 2 days (48 h), and 7 days (168 h). The solution was renewed after 2 and 50 hours extraction time. Nutrient pools expressed as g m^–2 to soil depth 100 cm, and a base index (Ca²⁺+ Mg²⁺+ K⁺ (mol_c m^–2) : Ca²⁺ + Mg²⁺ + K⁺ + Al³⁺ (mol_c m^–2)) were interpreted in relation to soil texture classes. Subsoil texture classes: Coarse: < 5 % clay; medium 5–10 % clay or (> 5 % silt or > 50 % fine sand), or fine > 10 % clay were evaluated as an indicator of forest soil quality. Base cation and phosphorus release decreased in the order fine > medium > coarse. Texture classes explained base cation release by about 80 % of total variation, and phosphorus release by 40–50 %. The base index generally increased by extraction time for sandy soils and decreased for loamy soils. This indicated that sandy soils released accumulated reactive aluminum in the 0–2 hour extraction. Subsoil texture class is suggested as a pedotransfer function for long‐term nutrient release potential in Danish forest soils.     

Profile Distribution of Carbon Fractions Under Long‐term Rice‐wheat and Maize‐wheat Production in Alfisols and Inceptisols of Northwest India

The knowledge of profile distribution of soil organic carbon (SOC) in long‐term agricultural systems could help to store atmospheric carbon in the soil. We investigated profile distribution of easily oxidisable Walkley–Black SOC pool (SOC_WB) under long‐term rice‐wheat (R‐W) and maize‐wheat (M‐W) cropping systems under soils of different pedogenesis. The soil samples were collected from the characteristic genetic horizons and analysed for carbon fractions. The SOC_WB was the highest in soils under R‐W systems in both Alfisols and Inceptisols. The SOC_WB stock in the deeper profile horizons under R‐W system was significantly (p < 0·05) higher than that under M‐W system especially in Typic Hapludalfs. Long‐term R‐W system could store on average 3·55 Mg ha⁻¹ more SOC_WB than M‐W system in the Ap horizon. The SOC_WB stock in the Ap horizon of all pedons was significantly (p < 0·05) higher in Alfisols than that in Inceptisols. About 60–90% of the total profile SOC_WB stock was contributed by B‐horizon because of its greater extent. Considering the whole profile, clay was negatively correlated with SOC fractions; however, the SOC fractions were closely related to each other. This study reveals that the distribution of SOC_WB is different in long‐term R‐W and M‐W systems not only in surface but also in the deeper horizons and the magnitude of the variation is influenced by the specific pedogenic processes. This indicates the significance of profile SOC_WB stock instead of topsoil SOC_WB stock in quantifying carbon retention potential of the long‐term management practices. Copyright © 2014 John Wiley & Sons, Ltd.     

Soil micronutrient contents and relation to other soil properties in Ethiopia

Abstract

Alfisols, Vertisols, Inceptisols, Aridisols, Mollisols, and Entisols were sampled (0–30 cm) from 32 locations across Ethiopia. The soils were analyzed for copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe) contents using 0.005 M diethylene triamine pentaacetic acid (DTPA), 0.05 M hydrochloric acid (HC1), and 0.02 M ethylene diamine tetraacetic acid (EDTA) extractants. EDTA extracted more of each micronutrient than DTPA, which extracted greater amounts than HC1. The quantities of EDTA and DTPA‐extractable micronutrients were significantly correlated, and were in the order: Mn>Fe>Cu>Zn. The order of HCl‐extractable micronutrients was Mn>Fe>Zn>Cu. Micronutrient contents of Mollisols, Vertisols, and Alfisols were usually greater than those of the other soils, and Entisols usually had the lowest micronutrient contents. The contents were mostly positively correlated with clay and Fe₂O₃ contents, but negatively correlated with soil pH and A1₂O₃contents. While comparison of DTPA‐ and EDTA‐extractable micronutrients with critical levels showed that most soils had adequate amounts of the micronutrients for crops, the amounts extracted by HC1 were below critical levels in most soils. Since the critical levels that were used in the comparisons were not established in Ethiopia, calibration of the soil contents of these micronutrients with crops grown in Ethiopia is required to identify the most suitable extractant(s).     

The nature and composition of amorphous material and free oxides in some temperate region and tropical soils

Abstract

Amorphous clay separated from pedons of a highly weathered soil previously classified as Oxisol and an Ultisol of the Southern States and, from the surface horizons of an Oxisol and two Andepts of the tropics were studied by chemical, DTA, infrared and X‐ray analysis.

Considerable amounts of amorphous material, 20–37% in temperate region and 29–40% in tropical soils, were extracted by differential dissolution using 0.5 N NaOH. The molar SiO₂/Al₂O₃ ratios of the dissolved material varied from sesquioxidic to siliceous (0.36–9.1) in temperate region soils, whereas those of the Andepts were allophonic (1.5–1.7). DTA and infrared analysis confirmed these results, however the strong gibbsite peaks in the X‐ray analysis of temperate region soils suggested that the aluminum fraction dissolved was in part, if not all, crystalline in nature. Indications were obtained with DTA and infrared that Na‐dithionite treatment might have altered the nature of the clay.     

Biodegradation kinetics of monosaccharides and their contribution to basal respiration in tropical forest soils

Low molecular weight (LMW) organic compounds in soil solution are easily biodegradable and could fuel respiration by soil microorganisms. Our main aim was to study the mineralization kinetics of monosaccharides using ¹⁴C-radiolabelled glucose. Based on these data and the soil solution concentrations of monosaccharides, we evaluated the contribution of monosaccharides to basal respiration for a variety of tropical forest soils. Further, the factors controlling the mineralization kinetics of monosaccharides were examined by comparing tropical and temperate forest soils. Monosaccharides comprised on average 5.2 to 47.7% of dissolved organic carbon in soil solution. Their kinetic parameters (V _max and K_M ), which were described by a single Michaelis-Menten equation, varied widely from 11 to 152?nmol?g^?1?h^?1 and 198 to 1294?µmol?L^?1 for tropical soils, and from 182 to 400?nmol?g^?1?h^?1 and 1277 to 3150?µmol?L^?1 for temperate soils, respectively. The values of V _max increased with increasing microbial biomass-C in tropical and temperate soils, while the K_M values had no correlations with soil biological or physicochemical properties. The positive correlation between V _max values and microbial biomass-C indicates that microbial biomass-C is an essential factor to regulate the V _max values in tropical and temperate forest soils. The biodegradation kinetics of monosaccharides indicate that the microbial capacity of monosaccharide mineralization far exceeds its rate at soil solution concentration. Monosaccharides in soil solution are rapidly mineralized, and their mean residence times in this study were very short (0.4–1.9?h) in tropical forests. The rates of monosaccharide mineralization at actual soil solution concentrations made up 22–118% of basal respiration. Probably because of the rapid and continuous production and consumption of monosaccharides, monosaccharide mineralization is shown to be a dominant fraction of basal respiration in tropical forest soils, as well as in temperate and boreal forest soils.     

Influence of vegetation types and soil properties on microbial biomass carbon and metabolic quotients in temperate volcanic and tropical forest soils

Abstract

There is limited knowledge about the differences in carbon availability and metabolic quotients in temperate volcanic and tropical forest soils, and associated key influencing factors. Forest soils at various depths were sampled under a tropical rainforest and adjacent tea garden after clear-cutting, and under three temperate forests developed on a volcanic soil (e.g. Betula ermanii and Picea jezoensis, and Pinus koraiensis mainly mixed with Tilia amurensis, Fraxinus mandshurica and Quercus mongolica), to study soil microbial biomass carbon (MBC) concentration and metabolic quotients (qCO₂, CO₂-C/biomass-C). Soil MBC concentration and CO₂ evolution were measured over 7-day and 21-day incubation periods, respectively, along with the main properties of the soils. On the basis of soil total C, both CO₂ evolution and MBC concentrations appeared to decrease with increasing soil depth. There was a maximal qCO₂ in the 0–2.5 cm soil under each forest stand. Neither incubation period affected the CO₂ evolution rates, but incubation period did induce a significant difference in MBC concentration and qCO₂ in tea soil and Picea jezoensis forest soil. The conversion of a tropical rainforest to a tea garden reduced the CO₂ evolution and increased the qCO₂ in soil. Comparing temperate and tropical forests, the results show that both Pinus koraiensis mixed with hardwoods and rainforest soil at less than 20 cm depth had a larger MBC concentration relative to soil total C and a lower qCO₂ during both incubation periods, suggesting that microbial communities in both soils were more efficient in carbon use than communities in the other soils. Factor and regression analysis indicated that the 85% variation of the qCO₂ in forest soils could be explained by soil properties such as the C:N ratio and the concentration of water soluble organic C and exchangeable Al (P < 0.001). The qCO₂ values in forest soils, particularly in temperate volcanic forest soils, decreased with an increasing Al/C ratio in water-soluble organic matter. Soil properties, such as exchangeable Ca, Mg and Al and water-soluble organic C:N ratio, were associated with the variation of MBC. Thus, MBC concentrations and qCO₂ of the soils are useful soil parameters for studying soil C availability and microbial utilization efficiency under temperate and tropical forests.     

The fate of catechol in soil as affected by earthworms and clay

The effect of endogeic earthworms (Octolasion tyrtaeum) and the availability of clay (Montmorillonite) on the mobilization and stabilization of uniformly ¹⁴C-labelled catechol mixed into arable and forest soil was investigated in a short- and a long-term microcosm experiment. By using arable and forest soil the effect of earthworms and clay in soils differing in the saturation of the mineral matrix with organic matter was investigated. In the short-term experiment microcosms were destructively sampled when the soil had been transformed into casts. In the long-term experiment earthworm casts produced during 7 days and non-processed soil were incubated for three further months. Production of CO₂ and ¹⁴CO₂ were measured at regular intervals. Accumulation of ¹⁴C in humic fractions (DOM, fulvic acids, humic acids and humin) of the casts and the non-processed soil and incorporation of ¹⁴C into earthworm tissue were determined.Incorporation of ¹⁴C into earthworm tissue was low, with 0.1 and 0.44% recovered in the short- and long-term experiment, respectively, suggesting that endogeic earthworms preferentially assimilate non-phenolic soil carbon. Cumulative production of CO₂-C was significantly increased in casts produced from the arable soil, but lower in casts produced from the forest soil; generally, the production of CO₂-C was higher in forest than in arable soil. Both soils differed in the pattern of ¹⁴CO₂-C production; initially it was higher in the forest soil than in the arable soil, whereas later the opposite was true. Octolasion tyrtaeum did not affect ¹⁴CO₂-C production in the forest soil, but increased it in the arable soil early in the experiment; clay counteracted this effect. Clay and O. tyrtaeum did not affect integration of ¹⁴C into humic fractions of the forest soil. In contrast, in the arable soil O. tyrtaeum increased the amount of ¹⁴C in the labile fractions, whereas clay increased it in the humin fraction.The results indicate that endogeic earthworms increase microbial activity and thus mineralization of phenolic compounds, whereas clay decreases it presumably by binding phenolic compounds to clay particles when passing through the earthworm gut. Endogeic earthworms and clay are only of minor importance for the fate of catechol in soils with high organic matter, clay and microbial biomass concentrations, but in contrast affect the fate of phenolic compounds in low clay soils.     

昆明地区不同母质对红壤发育的影响

昆明地区位于云南省中部,为我国西南高原红壤的主要分布区。关于本区土壤形成过程及发生分类等同题,虽然曾有人做过不少工作,但至今仍存在着一些分歧;有人认为本区土壤的形成过程以砖红壤化为主,土壤类型为砖红壤及铁质砖红壤性土^[1,2];有人认为棕壤化为本区土壤的主要成土过程,土壤应命名为棕色森林土^[4];另有人认为本区土壤属红壤,目前的成土过程为红壤化^[5],所有这些意见,均因资料不足而难取得统一。     

Classifying soils at the ultimate stage of weathering in the tropics

Oxisols cover ≈ 23% of the land surface in the tropics and are utilized extensively for agricultural purposes in the tropical countries. Under the variable input types of agricultural systems practiced locally, some of these soils still appear to have problems in terms of proper soil classification and subsequently hinder attempts to implement sustainable agro‐management protocols. The definition for Oxisols in Soil Survey Staff (1999) indicates that additional input is still required to refine the definition in order to resolve some of the outstanding classification problems. Therefore, the objective of this study is to examine the properties of some Oxisols and closely related soils in order to evaluate the classification of these soils. Soils from Brazil, several countries in Africa, and Malaysia were used in this study. Field observations provided the first indication that some of the presently classified kandi‐Alfisols and kandi‐Ultisols were closer to Oxisols in terms of their properties. Water‐retention differences and apparent CEC of the subsurface horizons also supported this idea. The types of extractable Fe oxides and external specific surface areas of the clay fractions showed that many kandic horizons have surface properties that are similar to the oxic horizons. Micromorphology indicated that the genetic transition from the argillic to the oxic involves a diminishing expression of the argillic. Properties, such as CEC, become dominant. The kandic horizon is therefore inferred as a transition to the oxic horizon. It is proposed that the Oxisols be keyed out based only on the presence of an oxic horizon and an iso–soil temperature regime. The presence of a kandic horizon will be reflected at lower levels in Oxisols. The Oxisols will now be exclusive to the intertropical belt with an iso–soil temperature regime. The geographic extend of the Oxisols would increase and that of kandi‐Alfisols and Ultisols would decrease. A few kandi‐Alfisols and Ultisols in the intertropical area will have low CEC which would fail the weatherable mineral contents. The kandic subgroups of some Alfisols and Ultisols will be transitional between the low (< 16 cmol_c [kg clay]^–1)‐ and high (> 24 cmol_c [kg clay]^–1)‐activity clay soils. The proposed changes to classification will contribute to a better differentiation of the landscape units in the field. Testing of the proposed classification on some Malaysian soils showed that the new definition for Oxisols provides a better basis for the classification of the local soils and the development of meaningful soil‐management groups for plantations.     

华中黄棕壤和黄褐土粘粒胶膜的微量元素地球化学特征

The relationships between the basic properties and trace elementsin soil argillans and corresponding matrix soils were studied by sampling from the B horizons of 26 Alfisols in croplands of the subtropical area in Central China. The soil elements (K, Na, Ca, Mg, Mn, Co, Cu, Cr, Cd, Li, Mo, Ni, Pb, Ti, V, and Zn) were extracted by acid digestion and their contents were measured using inductively coupled plasma optical emission spectrometry (ICP-OES). The mean contents of clay and organic matter in the argillans were approximately 1.1 and 1.3 times greater than those in the matrix soils, respectively. The pH values and the contents of P₂O₅ and bases (K₂O, Na₂O, CaO, and MgO) in the argillans were higher than those in the corresponding matrix soils. Cu, Cd, Ti, and V were enriched in the argillans. Correlation coefficients and factor analyses showed that Co, Cu, Li, and Zn were bound with phyllosilicates and manganese oxides (Mn-oxides) in the argillans. Cr and Pb were mainly associated with iron oxides (Fe-oxides), while Ni was bound with Mn-oxides. Cd, Ti, and V were chiefly associated with phyllosilicates, but Cr and Mo were rarely enriched in the argillans. In contrast, in the matrix soils, Co and Zn were associated with organic matter and Fe-oxides, Cr existed in phyllosilicates, and Mo was bound to Fe-oxides. Cd, Ti, and V were associated with organic matter. The results of this study suggest that clays, organic matter, and minerals in the argillans dominate the illuviation of trace elements in Alfisols. Argillans might be the active interfaces of elemental exchange and nutrient supply in cropland soils in Central China.