灰壤形成中的化学过程

灰壤中灰化淀积层的形成是一系列化学反应的结果，主要的化学过程有氧化还原反应，有机络合反应和等电点沉淀反应。

台湾红壤及森林土壤中之氧化铁

本文综合汇整近年来在台湾，应用高梯度磁场分离技术，配合一般化学分析，Ｘ－射线衍射法，磁测分析，电子显微镜观察与电子衍射鉴定，以及铁－５７穆斯堡尔谱学分析等方法，研究红壤与森林土壤中，氧化铁的分布及其结构性质之成果回顾；关于氧化铁之分布情形，其研究结果显示：台湾红壤中普遍存在有赤铁矿与针铁矿等氧化铁矿物，而在化育自大屯山更新世纪安山岩母质与澎湖列岛更新世纪玄武岩母质的红壤中，以及兰屿绿岛海边之银白色海砂，由于亦存在有磁铁矿与磁赤铁矿等强磁性矿物，致使其具有强磁感率。在寿卡一带之红壤以及标高约２０００ｍ高山的森林土壤中，则发现含有纤铁矿，利用Ｘ－射线衍射鉴定以及穆斯堡尔谱学分析，证实寿卡红壤经高梯度磁分离后之磁性粘粒部分，含有针铁矿、纤铁矿，晶性不良之赤铁矿，以及含铁绿泥石，其中含铁绿泥石构造中之两价铁，乃位于类似滑石之顺式配位座落中；而从电子显微镜观察高山灰化土中，与纤铁矿共存之针铁矿，发现其为表面平滑，透光度规则之条状晶体，以电子衍射鉴定证实此构形乃由钉铁矿（１００）面上俯瞰之结果。

酸雨、土壤酸化与森林衰亡

本文主要综述酸雨通过土壤酸化导致森林衰亡方面的国外最新研究进展。对于森林衰亡的原因目前主要有几种假说:综合胁迫;土壤的酸化——铝毒害;气态污染物(SO_2,O_3);酸雨——镁亏缺和过量营养物铵/氮沉降等。这些假说都有一定的事实依据,并直接或间接涉及酸雨问题。酸雨在很大程度上是通过土壤——植物系统间接危害森林的。长期持续的酸雨输入导致土壤酸度升高,减少可利用态磷,降低有机质的分解速率,抑制氮的矿化作用;土壤酸度升高使钙、镁等离子易被淋失造成营养元素亏缺,溶出铝和某些重金属离子毒害植物。

我国灰土的分类

讨论了灰土的成土条件、成土特点、形态特征及灰土的分类。

酸雨对酸性土壤的影响—一种新见解

普遍认为,北美和北欧地区土壤和水的酸化是酸雨所致.然而,通常认为,使地表易受酸雨酸化作用影响的因素,与早已了解的在土壤自然形成的整个过程中使土壤严重酸化的因素是相同的.正在遭受酸化的地区,又已经恢复了极其粗略的土地利用制度.显然,在由于土地利用及随之发生的植物演替变化所引起的长期酸化作用下,又增加了酸雨的酸化作用.因此,必须以评价所提出的减少二氧化硫及氮氧化物排放量的预期效益为基准,仔细考察酸雨、酸性土壤和植被之间的相互作用,

1957～1990年西北威尔士地区土壤酸性的增加

由自然界或人类活动排出的氧化硫或氧化氮所造成的酸沉降,会加剧土壤中阳离子的淋溶。如果土壤排水析出的主要离子是硫或氮,那么,为了保持土壤电荷呈中性就需要当量浓度阳离子。析出的阳离子常常被土壤交换体系用氢离子替代,结果,土壤的酸度增加。欧洲许多国家都报道过这种主要由人为排放二氧化硫和二氧化氮造成的土壤酸化问题。然而。

希腊香料烟主要品种介绍

1989年5月至8月,我们随中国烟草总公司代表团在希腊考察香料烟生产技术。了解到地处欧洲巴尔干半岛南端的希腊,境内地势起伏、山区、半山区、平原兼有、土壤类型多样.代表性土壤为砂性灰壤和褐红色地中海山地土,含石度较高、通透性强、土层浅薄、硅和锰含量高、养分含量低。希腊自然气候差异较大,南部为亚热带地中海型气候,北部和西北部为大陆性气候。

Relationships between Application Amount of Quicklime and Soil Nutrients,Flue-cured Tobacco Quality in Panzhihua City

[Objective] This study aimed to investigate the improving effect of quick- lime on acid soil in tobacco-growing areas in Panzhihua City. [Method] The effects of four application amounts （450, 900, 1 350 and 1 800 kg/hm2） of quicklime on soil nutrients and flue-cured tobacco quality were observed for two consecutive years. [Result] In acid soil, the application of quicklime significantly improved soil pH. In addition, it showed significant effects on soil nutrients, flue-cured tobacco quality, tobacco output and tobacco leaf chemical components. When the application amount of quicklime was increased to 1 350 kg/hm2, the improving effect of quick- lime on soil nutrients was best, the flue-cured tobacco yield and quality all reached the highest, and the chemical components of tobacco leaves were closest to the in- herent indicators of high-quality tobacco leaves. [Conclusion] This study will provide certain reference for accurate application of quicklime in tobacco-growing area in Panzhihua City.

Phosphorus Changes and Sorption Characteristics in a Calcareous Soil Under Long-Term Fertilization

Knowledge of phosphorus （P） behavior in long-term fertilized soils is essential for programming fertilization practices and for sustaining environmental quality. The long-term （1984-1997） effects of various fertilization treatments on P changes and sorption isotherms as well as the relationship of soil properties to P sorption and P forms were evaluated in an Ustic Isohumisol, a calcareous soil, on the Loess Plateau, China. Compared to 1984, after 13 years of crop production, total soil P in the no-P treatments （control and N treatment） decreased by 5%-7%, but in the phosphorus fertilizer alone （P）, nitrogen and phosphorus fertilizers in combination （NP）, manure alone （M）, and nitrogen and phosphorus fertilizers and manure in combination （NPM） treatments, it increased by 22%, 19%, 28%, and 58%, respectively. Residual fertilizer P was found mainly in NH4Ac-soluble P （Cas-P）, followed by NaHCO3-soluble P （NaHCO3-P）, and NH4F-soluble P （Al-P）. Phosphorus sorption in the soils with different fertilization practices fit the Langmuir equations. Phosphorus sorption capacity in the no-P treatments increased, whereas it decreased in the P-included treatments （P, NP, and NPM treatments）. Phosphorus sorption maximum （Qm） was significantly and negatively correlated to inorganic P including NaHCO3-P, Cas-P, NaOH-Na2CO3-soluble P （Fe-P）, and Al-P （P ≤ 0.01）. Moreover, long-term fertilization increased soil organic carbon in the NP, M, and NPM treatments and decreased pH in the NP and NPM treatments. Thus, the ability of the soil to release sorbed P to the environment increased under long-term P fertilization.

Response of Tomato on Calcareous Soils to Different Seedbed Phosphorus Application Rates

Field experiments were conducted with five rates （0, 75, 150, 225, and 450 kg P205 ha^-1） of seedbed P fertilizer application to investigate the yield of tomato in response to fertilizer P rate on calcareous soils with widely different levels of Olsen P （13-142 mg kg^-1） at 15 sites in some suburban counties of Beijing in 1999. Under the condition of no P fertilizer application, tomato yield generally increased with an increase in soil test P levels, and the agronomic level for soil testing P measured with Olsen method was 50 or 82 mg kg^-1 soil to achieve 85% or 95% of maximum tomato yield, respectively. With regard to marketable yield, in the fields where Olsen-P levels were 〈 50 mg kg^-1, noticeable responses to applied P were observed. On the basis of a linear plateau regression, the optimum seedbed P application rate in the P-insufflcient fields was 125 kg P205 ha^-1 or about 1.5-2 times the P removal from harvested tomato plants. In contrast, in fields with moderate （50 〈 Olsen P 〈 90 mg kg^-1） or high （Olsen P 〉 90 mg kg^-1） available P, there was no marked effect on tomato fruit yield. Field survey data indicated that in most fields with conventional P management, a P surplus typically occurred. Thus, once the soil test P level reached the optimum for crop yield, it was recommended that P fertilizer application be restricted or eliminated to minimize negative environmental effects.

Acidity Regimes of Soils Under Different Vegetations in the Changbai Mountains Region

The acidity regimes of representative soils on the north slope of the Changbai Mountains were examined through determinations of PH and pCa of the soil paste as well as in-site determinations. For soils under broad-leaf forest or broad-leaf-Korean pine forest, the pH decreased from the litter to lower layers gradually until it did not change or decreased further slightly. For soils under coniferous forest or Ermans birch forest,there was a minimum in pH at a depth of 3～6 cm where the content of humus was high. The pCa increased gradually from the soil surface downward to a constant value. The lime potential (pH-0.5pCa) showed a similar trend as the PH in its distribution. For a given soil, the measured pH value of the thick paste, ranging from 4.5 to 5.5, was lower by about 0.5 units than the value determined by the conventional method with a water to soil ratio of 5:1. The PH determined in site was even lower. It was found that there was a fairly close relationship between soil acidity and the type of vegetation. The pH showed a trend of decreasing from soils under broad-leaf forest through broad-leaf-conifer mixed forest and coniferous forest to Ermans birch forest, and the pCa showed an opposite trend in variation.

Geographical Tendencies of Trace Element Contents in Soils Derived from Granite,Basalt and Limestone of Eastern China

92 soil samples were collected from granite, basalt and limestone areas of eastern China and determined for 13 trace element contents. The geographical tendencies of and factors affecting trace element contents in soils were studied.The sequences of soil trace element contents (especially the transitional elements in the 4th period) were: basalt soils > limestone soils > granite soils.The contents of trace elements in soils of granite areas and basalt areas showed great inheritance of trace element contents from the relevant parent rocks. The contents of trace elements in limestones were very low, but they became very high in limestone soils. Trace element contents of soils derived from limestone and basalt'increased significantly from north to south, these tendencies were similar to the tendency of ferric oxide contents in soils.There were differences of contents of trace elements bound to ferric oxide in different kinds of parent material and in different types of soil. The correlations between the contents of trace elements and the contents of ferric oxide were better in basalt soils than in granite soils.

Effect of Composts,Lime and Diammonium Phosphate on the Phytoavailability of Heavy Metals in a Copper Mine Tailing Soil

Soil samples from a historic copper mine tailing site at the Parys Mountain,North Wales(UK) were amended with green waste compost(GC),GC+30% sewage sludge(GCS),lime and diammonium phosphate(DAP),to determine the effect of amendments on DTPA-and Ca(NO3)2-extractable metals in the mine tailing and on the phytoavailability of heavy metals by a lettuce(Lactuca sativa L.).Both compost were added at the rate of 10% by weight,lime was added as calcium carbonate equivalent(pH = 7) and DAP at a 2300 mg kg-1 soil level.The experiment was arranged in randomised complete design with three replicates in pots under control environment.Addition of lime resulted in the largest reduction in metal extractability with DTPA and Ca(NO3)2 and phytoavailability of Cu,Fe and Zn while DAP was effective in lowering Pb extractability and phytoavailability.With exception of Zn,all other metals extracted decreased with time after amendment applications.The distribution of heavy metals between and within the four procedures of potentially bioavailable sequential extraction(PBASE) varied significantly(P < 0.001).Stronger relationships were noted between the metals extracted with PBASE SE1 and Cu,Pb(P < 0.01) and Fe(P < 0.001) in the lettuce.These results indicate that addition of lime is sufficient to restore the vegetative cover to a high metal mine waste while DAP is good for stabilizing Pb,but its detrimental role on plant growth and the risk associated with presence of N in DAP(through N leaching) may restrict its chances for remediation of contaminated sites.

Effects of different long-term crop straw management practices on ammonia volatilization from subtropical calcareous agricultural soil

Ammonia(NH3)volatilized from agricultural production and its secondary aerosols contribute greatly to air pollution.Different long-term crop straw management practices may significantly affect the soil fertility and soil nitrogen cycle,however,the effect on NH3 volatilization has not been well studied.Therefore,a one-year field experiment was conducted to evaluate the effect of straw incorporation on NH3 volatilization from subtropical calcareous agricultural soil from a longterm perspective,including four treatments:synthetic fertilizer(CK);synthetic fertilizer incorporation with 100%or 50%of the previous season’s crop straw(SI1 and SI2,respectively);and synthetic fertilizer incorporation with 50%burned crop straw(SI2B).Soil NH3 volatilizations were monitored through a wheat–maize rotation year by using a dynamic chamber method.The results demonstrated that NH3 volatilization primarily occurred within 38 days and 7–10 days following nitrogen fertilization events for the wheat and maize seasons,respectively.Different crop straw management practices mainly impacted the NH3 flux of the basal fertilization rather than the topdressing fertilization;long-term crop straw incorporation effectively lowered NH3 loss(35.1%for SI1 and 16.1%for SI2 compared to CK;and the inhibiting effect increased with increasing straw amount,possibly contributed by the high straw carbon/nitrogen ratio,and enhanced microbial activity,which contributed to inorganic nitrogen immobilization and lower ammonium content in the topsoil.However,SI2B significantly increased(29.9%)the annual NH3 flux compared with SI2,indicating that long-term 100%straw incorporation could be a promising straw management practice for mitigating NH3 loss and increasing soil fertility.

Alleviation of Subsoil Acidity of Red Soil in Southeast China with Lime and Gypsum *1

Application of lime or gypsum is a common agricultural practice to ameliorate soils with low pH which prohibits crop production. Its integrated effect on soil properties in a red soil derived from Quaternary red clay in Southeast China is discussed in this paper. Application of gypsum in the topsoil without leaching raised soil pH and promoted the production of soil NH 4, but lime addition had a contrary effect. Generally, application of lime and/or gypsum has little effect on soil electrical properties. Gypsum had a little effect on soil exchange complex and its effect went down to 30 cm in depth. The effect of lime reached only to 5 cm below its application layer. With leaching, Ca transferred from top soil to subsoil and decreased exchangeable Al in subsoil. Gypsum application led to a sharp decrease in soil exchangeable Mg but had no effect on K.

Transformation of Applied Phosphorus in a Calcareous Fluvisol

A new inorganic phosphorus (IP) fractionation scheme developed by Jiang and Gu was used in an incubation experiment to investigate the transformation of applied P in a calcareous fluvisol. The results show that after addition of common superphosphate (CSP), the Ca2-P in the soil decreased gradually and transformed largely to the less available Fe-P, Al-P and Ca8-P, rather than to the unavailable forms of Ca10-P and O-P. The different IP fractions ranked in the following order with respect to the increment by addition of CSP after 120 days of incubation: Fe-P> Al-P>Ca8-P>Ca2-P. After addition of pig manure, the content of Ca2-P in the soil increased rapidly at first and then decreased slowly, and the amount of different IP fractions accumulated after 120 days of incubation ranked in the following order: Ca2-P > Fe-P > Ca8-P > Al-P. Evidently, the variation in content of Ca2-P and the order of increase in different IP fractions in incubation induced by application of pig manure were quite different from that of CSP. The increase in IP fractions in the incubation of broad bean green manure (BBGM)for 120 days was in the rank of Fe-P > Ca2-P > Ca8-P > Al-P; but because organic phosphorus (OP) of BBGM degraded relatively slowly, the increment in IP fractions was lower than that of pig manure. Wheat straw was difficult to mineralize and induced a strong biological fixation of soil P, resulting in a decrease of the content of Ca2-P, even Ca8-P, Fe-P and Al-P.

Characteristics and distributions of humic acids in two soil profiles of the southwest China Karst area

Characteristics and distributions of humic acid(HA) and soil organic matter(SOM) in a yellow soil profile and a limestone soil profile of the southwest China Karst area were systematically investigated to reveal their evolutions in different soils of the study area. The results showed that characteristics and distribution of SOM along the two soil profiles were notably different. Total organic carbon(TOC) contents of soil samples decreased just slightly along the limestone soil profile but sharply along the yellow soil profile. TOCs of the limestone soils were significantly higher than those of the corresponding yellow soils, and C/N ratios of SOMs showed a similar variation trend to that of TOCs, indicating that SOM can be better conserved in the limestone soil than in the yellow soil. The soil humic acids were exhaustively extracted and further fractionated according to their apparent molecular weights using ultrafiltration techniques to explore underlying conservation mechanisms. The result showed that C/N ratios of HAs from different limestone soil layers were relatively stable and that large molecular HA fractions predominated the bulk HA of the top soil, indicating that HA in the limestone profile was protected while bio and chemical degradations were retarded. Combined with organic elements contents and mineral contents of two soils, weconcluded that high calcium contents in limestone soils may play a key role in SOM conservation by forming complexation compounds with HAs or/and enclosing SOMs with hypergene CaCO_3 precipitation.

Uptake of Organic Phosphorus by Arbuscular Mycorrhizal Red Clover

The capacities of two arbuscular mycorrhizal (AM) fungi, Glomusmosseae and Glomus versiforme, to mineralize added organic P werestudied in a sterilized clacareous soil. Mycorrhizal (inoculated witheither of the AM fungi) and non-mycorrhizal red clover (Trifoliumpratense L.) plants were grown for eight weeks in pots with upperroot, central hyphal and lower soil compartments. The hyphal and soilcompartments received either organic P (as Na-phytte) or inorganic P(as KH_2PO_4) at the rate of 50 mg P kg^-1. No P was added to theroot compartments.

Application of NaHCO_3/ DTPA Extractant-ICP Spectrometry Technique in Soil Test for Availability of Nutrients and Heavy Metals

Soil test for availability of nutrients and heavy metals is extensively served as a means for the evaluations of soil fertility, and environmental effects and phytotoxicity of pollutants in soils, and for the fertilizer recommendation in agricultural and environmental sciences. Therefore, great attention has been paid to the measurement of elemental availability in soil test.

Effect of Perched Water Tables on Aluminosilicate Stability and Soil Genesis

The mineral stability and solute activities of soil solution extracted from selected horizons of seven studied pedons of Alfisols in Kentucky, USA, and the relationship between distribution of iron-manganese concretions and the restrictive layers were investigated. The results showed that the genesis and development of these soils and mineral weathering trends were strongly influenced by the depth of bedrock and the presence of perched water tables at lithic (limestone) interfaces due to the dissolution and buffering effect of limestone bedrock. The extractable Mg/Ca ratio as depth function and soil depth above bedrock could be used as indices of weathering and degree of soil development. Maximum iron-manganese concretion accumulation was found to occur in the horizon overlying clay horizon (>40% clay) with a sharp increase in clay content (>10%), which suggested that zones of Fe-Mn concretion accumulation in soils of the Inner Bluegrass Region appeared to be a sensitive genetic indicator of argillic horizons with restrictive permeability.