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1.
Volcanic ash soils along the western edge of the Omiya tableland, Japan, are covered with thick anthropogenic soil horizons. The formation of anthropogenic soil horizons occurs because of the soil dressing practice known as “Dorotsuke,” where alluvial soil materials are deposited on fields and mixed with volcanic ash topsoil by tillage over the years. To clarify the chronology of this anthropedogenesis, carbon-14 (14C) age profiles were estimated using humic acid fractions from three pedons: an anthropogenic soil, an undressed Andosol, and a Fluvisol. Soil charcoal fragments were also dated to estimate maximum burial age. Charcoal fragments displayed vertically random age distributions, indicating that the fragments may have had multiple origins. However, the age of charcoal in the lower part of the anthropogenic soil horizons indicated that the initiation of anthropedogenesis occurred later than the late 13th century. The 14C age profile of humic acid in the Andosol exhibited little variation in age with depth in the subsoil. The 14C age profile of humic acid in the Fluvisol suggested that the humic acid fraction included allochthonous old carbon (C), although the soil itself had been formed from recent sediments. The 14C age profile of humic acid in the anthropogenic soil showed features of its two component soils. The 14C ages in the volcanic ash subsoil matched with those in the Andosol, whereas the ages increased in the anthropogenic soil horizons because of supplementation with old C from alluvial soil materials. However, the peak 14C ages occurred in the lower part of the anthropogenic horizons, whereas the middle part on the peak position displayed a gradual age-depth gradient. This feature was interpreted as a sign of 14C activity equilibrium throughout anthropedogenesis. On the basis of this postulated 14C activity equilibrium, the linear age-depth gradient at the peak position was derived from differences in burial time, and burial ages were calculated by estimating steady-state 14C. The calculated ages were lower than the charcoal ages. These age estimates suggest that anthropedogenesis was initiated in the Middle Ages and reached an intermediate stage before or during the first half of the Edo period.  相似文献   

2.
It has been reported by many workers that various soil properties influence the retention of boron added to soils, but there is little infomration on the relative importance of these properties to boron retention and there is something controversial in the published results regarding the effects of different soil properties such as organic matter content, soil reaction, available calcium content and texture on boron retention (15). The present study was undertaken to obtain more detailed informations on the relationships between boron adsorption and different properties of soils, and on comparative contribution of soil constituents such as organic matter, sesquioxides and inorganic colloids to boron adsorption of soils. In Japan, boron deficiency symptoms of crops often appear in the fields of volcanic ash soils, and many experiments on boron application have been conducted to amend the boron deficiencies of the soils. It is considered that volcanic ash soils may have special characteristics concerning boron retention in comparison with nonvolcanic ash soils. In the present study, therefore, some volcanic ash soils were also taken as samples in addition to non-volcanic ash soils to confirm their speciality to boron retention.  相似文献   

3.
3-(3′,4′-Dihydroxyphenyl)-L-alanine (L-DOPA), which is a component of velvetbean (Mucuna pruriens), displays a high inhibitory activity to plant growth. The inhibitory activity is influenced by the presence of soils, because L-DOPA is eliminated in soils. In the present study, the effect of several soil types (volcanic ash, calcareous, and alluvial soils) on the L-DOPA disappearance was investigated at constant equilibrium pH values. In the presence of soils, L-DOPA disappeared with the reaction time, and the disappearance was associated with three reactions: adsorption reaction (characterized by fast and sudden disappearance of L-DOPA within the initial 8 h period), catalytic transformation reaction (constant L-DOPA disappearance throughout the reaction period), and biotransformation caused by microbial activity (accelerated L-DOPA disappearance observed after 72 h of reaction time). The adsorption and transformation reactions consisted of physicochemical reactions mediated by the presence of soils. The amount of L-DOPA adsorbed was largest in the presence of volcanic ash soil among the three soil types. It is likely that the mechanism of L-DOPA adsorption includes a ligand exchange reaction. In the presence of soils, L-DOPA transformation was observed at equilibrium pH values higher than 4 and it increased with increasing equilibrium pH values. In the absence of soil, however, L-DOPA transformation did not occur at an equilibrium pH value lower than 6.0, indicating that L-DOPA transformation was accelerated by the presence of soil. The rate of L-DOPA transformation mediated by soils at constant equilibrium pH value was in the following order: alluvial soil > calcareous soil > volcanic ash soil. The plant-growth-inhibitory activity of L-DOPA was also reduced by the presence of soils, and the reduction in the case of L-DOPA was more obvious than in the case of 2,4-dichlorophenoxyacetic acid (2,4-D). Based on the reduction effect of soils on the plant-growth-inhibitory activity of L-DOPA (without pH-adjustment), calcareous soil ranked first, followed by volcanic ash soil, then alluvial soil. This was because the calcareous soil showed the highest soil pH value (7.8), and thereby the L-DOPA transformation reaction was accelerated. In soils with high pH values, the plant-growth-inhibitory activity of L-DOPA could therefore not be detected.  相似文献   

4.
The spatial distribution of major soil horizons and layers of pyroclastic deposits in Kamchatka was analyzed with the use of GIS technologies. For this purpose, the attribute soil database and the computer-supported cartographic database were developed. Their analysis with the help of GIS technologies made it possible to study the dependence of the morphology of soil profiles on the bioclimatic conditions and on the stratification of ash layers in the particular areas of Kamchatka and to develop the cartographic model of the areas of soil horizons. The concept of tephra stratotypes—the particular combinations of ash layers in the profiles of volcanic soils—was verified on the basis of factual materials. It was shown that tephra stratotypes affect many important soil properties and specify the direction of soil formation in Kamchatka. Several major tephra stratotypes differing in their morphology and environmentally important features were distinguished in Central Kamchatka. The method of soil mapping on the basis of the concept of tephra stratotypes with due account for the specificity of surface organic horizons of soils was developed. It is argued that this method makes it possible to reflect the specificity of soil formation in volcanic regions.  相似文献   

5.
Soils found on fan surfaces in the Kokoda Valley are derived from both volcanic ash and river alluvium. The alluvium is variable, some of it being mixed with volcanic ash. The main differences in the micromorphology of the soils appear to be related to the relative amounts of volcanic ash present in the soil profile. The plasma of soils formed on volcanic ash is isotropic in thin section. The plasma of alluvial soils exhibits increasing birefringence with decreasing amounts of volcanic ash. It is suggested that random structures in the clay fraction of the volcanic ash may account for its isotropic nature.  相似文献   

6.
《Geoderma》2005,124(3-4):253-265
To test the applicability of the Soil Reference Base of Soil Resources (ISSS/ISRIC/FAO, 1998. World Reference Base for Soil Resources, World Soil Resources Report 84, FAO, Rome) for soils derived from anthropogenic substrates, soils developed on lignite ashes in Germany which have some similarities with andosols were compared with natural volcanic soils from different countries. Soil parameters used for comparison were bulk density, clay content, Alo+0.5 Feo, and P-retention, as they serve as diagnostic criteria to define either vitric or andic horizons. For Alo+0.5 Feo, and P-retention, there was no statistically significant difference between both soil groups, the bulk densities of the lignite ash-derived soils were even significantly lower than those of the natural volcanic soils. Moreover, pH, total organic carbon, cation exchange capacity as well as the contents of carbonates and gypsum were collated and differences emerged between both soil groups concerning the contents of carbonates, gypsum and total organic carbon. In case of the lignite ash-derived soils, these parameters as well as the contents of oxalate soluble oxides were strongly influenced by the composition of the anthropogenic parent material. Up to now, such soil materials are not included as soil-forming materials in the World Reference Base for Soil Resources. We therefore suggested the introduction of a new diagnostic soil material, the so-called technogenic soil material into the anthropogeomorphic soil materials and to introduce “technogenic anthrosols” as a new reference subunit. In our proposition, technogenic materials are defined as anthropogeomorphic materials which are formed by technical processes including a distinct degree of transformation and/or new formation of soil-forming materials. Soil materials are categorised as “technogenic” when they consist of more than 70% (by volume) of soil material derived from technical processes like, e.g. combustion products of fossil energy sources, sewage sludges, blast furnace slags, etc.To include as much information as possible into the name of a soil, we developed a concept of reference soil series for the WRB combining pedogenetic and lithogenic information. Within this concept, these soils should be considered to be a subunit of anthrosols (vitri- or andi-technogenic anthrosols) and the specific properties of the soil-forming material (coaly, calcaric, gypsiric) should be given as additional information as Reference Soil Series as well as texture and kind of parent material.  相似文献   

7.
Abstract

An Investigation was conducted to determine the content and distribution of total and DTPA‐extractable Zn in the genetic horizons of 72 agriculturally important soils from the six major mineral soil areas in Louisiana.

The concentration of total Zn appeared to vary more with the clay constituents of the soils and the amount of the element in the parent materials than with soil depth. The majority of the soils had the largest amounts of total Zn in the subsurface horizons. The range in total Zn for all soils and horizons was from 7.0 to 150.0 ppm.

The DTPA‐extractable Zn in all of the soils and horizons ranged from 0.08 to 4.22 ppm. In the majority of the soil profiles the highest concentration of extractable Zn was in the surface horizons. There was a decrease in the extractable Zn with increasing soil depth. The alluvial soils along the Ouachita and Mississippi Rivers, and the Mississippi Terrace soil areas contained relatively large amounts of DTPA‐extractable Zn.

In some soils the extractable Zn significantly correlated with total Zn. There was also a close relationship between extractable Zn and organic matter content, especially in the Ap horizons.  相似文献   

8.
Abstract

An experiment was conducted to help understand the contributions of different soil layers to soil fertility, plant growth, and response to fertilization. Douglas‐fir (Pseudotsuga menziesii) seedlings were used in a pot bioassay to delimit the effects of volcanic ash soils, urea fertilization at 100 and 200 ppm, and the technique of using undisturbed soil as a growth medium. Volcanic ash horizons contained more available phosphorus and mineralized more nitrogen than underlying horizons. Best seedling growth occurred in ash horizons fertilized with 200 ppm of urea‐N. Fertilization decreased soil pH, mycorrhizae formation and foliar‐P levels but increased foliar‐N. The technique of using undisturbed soil had little effect on seedling growth in the weak structured ash horizons but did decrease root weights in the moderate structured sub‐ash layers.  相似文献   

9.
Montane volcanic ash soils contain disproportionate amounts of soil organic carbon and thereby play an often underestimated role in the global carbon cycle.Given the central role of Al and Fe in stabilizing organic matter in volcanic ash soils,we assessed various extraction methods of Al,Fe,and C fractions from montane volcanic ash soils in northern Ecuador,aiming at elucidating the role of Al and Fe in stabilizing soil organic matter(SOM).We found extractions with cold sodium hydroxide,ammonium oxalate/oxalic acid,sodium pyrophosphate,and sodium tetraborate to be particularly useful.Combination of these methods yielded information about the role of the mineral phase in stabilizing organic matter and the differences in type and degree of complexation of organic matter with Al and Fe in the various horizons and soil profiles.Sodium tetraborate extraction proved the only soft extraction method that yielded simultaneous information about the Al,Fe,and C fractions extracted.It also appeared to differentiate between SOM fractions of different stability.The fractions of copper chloride-and potassium chloride-extractable Al were useful in assessing the total reactive and toxic Al fractions,respectively.The classical subdivision of organic matter into humic acids,fulvic acids,and humin added little useful information.The use of fulvic acids as a proxy for mobile organic matter as done in several model-based approaches seems invalid in the soils studied.  相似文献   

10.
The soil chemical properties and microbial numbers in three volcanic ash soils and two non-volcanic ash soils, which had been continuously subjected to the same tea cultivation practices (21 y), were investigated. The results obtained were as follows. 1) pH values of all the soils gradually decreased from the original pH value (near neutral or mildly acid pH) to strongly acid values of about 4 or lower. In contrast, long-term tea cultivation practices resulted in the increase of the total C and N contents in the surface layers (0–20 cm) while the contents remained stable in the subsurface layers (20–40 cm). The increase in the organic matter content in non-volcanic ash soils was presumably due to the accumulation of microbial residues. The availability of P increased markedly. 2) Numbers of bacteria, actinomycetes, fungi, and denitrifiers were higher in volcanic ash soils than in non-volcanic ash soils, and also higher in surface layers than in subsurface layers. The results suggest that in spite of the same cultivation practices, the soil depth and soil type affected the microbial numbers in the tea soils. Numbers of autotrophic NH4 + oxidizers were low in comparison with the numbers of autotrophic NO2 - oxidizers. Influence of soil type and soil depth on autotrophic nitrifiers was not clear. 3) Total C and N contents in the tea soils were parameters closely related to the numbers of bacteria, actinomycetes, and fungi. For actinomycetes and fungi, the prediction could be more accurate, especially for total N content, if the estimations could be made within the same soil layers. The numbers per unit of C or N were higher in the surface layers than in the subsurface layers. 4) High concentration of NO3 --N in the tea soils used suggests that nitrification could occur despite the low pH value (3.2-3.8). The negative relationship between the number of total bacteria or actinomycetes and soil NH4 +-N concentration suggests that some NH4 +-N was converted to organic microbial biomass-No.  相似文献   

11.
Volcanic ash soils contain very large stocks of soil organic matter (SOM) per unit area. Consequently, they constitute potential sources or sinks for the greenhouse gas carbon dioxide. Whether soils become a net carbon source or sink with climate and/or land‐use change depends on the stability of SOM against decomposition, which is influenced by stabilization mechanisms in the soil. To quantify organic carbon stocks and to clarify the importance of chemical and physical soil characteristics for carbon stabilization in volcanic ash soils, we applied selective extraction techniques, performed X‐ray diffraction analysis of the clay fraction and estimated pore‐size distribution of soils under natural upper montane forest and grassland (páramo) in the Ecuadorian Andes. Our results show that organic carbon stocks under both vegetation types are roughly twice as large as previously reported global averages for volcanic ash soils. SOM stabilization is suggested to be dominantly influenced by the following chemical and physical soil characteristics: (i) direct stabilization of SOM in organo‐metallic (Al‐humus) complexes, explaining at most 40% of carbon accumulation, (ii) indirect protection of SOM (notably aliphatic compounds) through low soil pH and toxic levels of Al, and probably also (iii) physical protection of SOM caused by a very large micro‐porosity. Moreover, in the case of the forest soils, inherent recalcitrance of OM itself was responsible for substantial accumulation in ectorganic horizons. Both vegetation types contributed to soil acidification, thus increasing SOM accumulation.  相似文献   

12.
Abstract

Alkaline‐soluble, acid‐precipitable organic matter from the Ah and Bm horizons of Chernozemic soils developed on four parent materials in each of three soil zones was analyzed for total and carboxyl acidity, and methoxyl groups. The values are expressed as meq/g dry ash‐free organic matter.

Total acidity generally was higher in the Black Chernozems than in the Brown Chernozems and higher in the Bm horizon than in the Ah horizon. The distribution of carboxyl acidity between the Ah and companion Bm horizons of individual soils appeared to be related to texture and rainfall.

The. methoxyl group content of the Brown Chernozems was larger than that of the .Dark Brown Chernozems, which in turn had a larger methoxyl group content than that of the Black Chernozems. It was concluded that the organic matter in the Ah horizons of the Brown Chernozems was not as humified as that of the Black Chernozems. The pH value and a minimum clay content are possible determining factors as to the amounts of methoxyl carbon present.  相似文献   

13.
Abstract

A method to determine the contents of imogolite and Al-rich allophane (Sil Al ? 1 : 2) in volcanic ash soils was presented. The method is based on the (1) assessment of the presence of Al-rich allophane in clays by successsive extraction with dithionite-citrate and oxalate-oxalic acid, (2) trimethylsilylation of soil clay with a mixture of hexamethyldisiloxane, HCl, and isopropyl alcohol, and determination of the content of monomeric Si based on the trimethylsilyl derivative of monomeric orthosilicate anion by gas / liquid chromatography, (3) determination of the total content of imogolite and Al-rich allophane based on the content of monomeric Si from imogolite, (4) determination of the imogolite content by Thermogravimetry (TG )-Differential Thermal Analysis (DTA) based on the weight loss due to endothermic dehydroxylation with maximum values at ca. 386°C, (5) calculation of the Al-rich allophane content by subtracting the imogolite content from the total content of these minerals, and (6) evaluation of the imogolite and Al-rich allophane content of soil by multiplying clay content of soil and the two mineral content of clay. The trimethylsilylation analysis was found to be reproducible, and the estimated total amounts of two minerals in clays by this method were adequately approximated to those evaluated from the amount of Si (= Sio) extracted with oxalate-oxalic acid after extraction with dithionite-citrate. The variation in the abmldance of two minerals in the soil horizons of volcanic ash soils from the San'in region indicated that this method is suitable for the profile-study of volcanic ash soils.  相似文献   

14.
Abstract

The objective of the present study was to clarify the influence of volcanic ash addition on soil carbon stocks and the carbon accumulation process in brown forest soils (BFS) in Japan. The degree of volcanic ash addition to the soil was estimated according to the acid ammonium oxalate extractable aluminum (Alox) and lithic fragment contents, and their vertical distribution patterns. The BFS was classified in order of increasing volcanic ash influence on the soil into the following types: high Alox content with no gravel (H-Alox-NGv), high Alox with a high gravel content (H-Alox-Gv), moderate Alox (M-Alox), and low Alox (L-Alox), and then analyzed for carbon content, carbon amount, carbon stock, Alox amount and pyrophosphate extractable aluminum (Alpy) amount. The correlation between the carbon and Alpy amounts and the relationship between the Alpy and Alox amounts in the BFS samples indicated that the amount of carbon is determined by Al—humus complex formation, which is defined by the active Al generated from additional volcanic ash in BFS soil samples of BFS. Therefore, soils with thicker horizons and greater amounts of Alox had higher carbon levels in deeper horizons. For this reason, soil carbon stocks at depths of 0–30 cm and 0–100 cm, and in the effective soil depth of BFS, were larger and followed the order H-Alox-NGv = H-Alox-Gv > M-Alox > L-Alox. Furthermore, successive accumulations of volcanic ash on the soil surface promoted soil carbon accumulation as a result of the development of the surface horizon in H-Alox-NGv BFS. Our results suggest that volcanic ash additions control the soil carbon accumulation of forest soil in Japan.  相似文献   

15.
《Geoderma》1986,37(2):137-147
P sorption curves (18 hours, 0.01 M CaCl2) were determined for various A, AB, B and C horizons of six Andepts. Two of these soils were formed in alluvially sorted and redeposited volcanic ash. P buffer capacity (PBC) and equilibrium solution P concentration (EPC) were derived from the curves. PBC was high for all samples indicating large sorption capacities. Soils formed in alluvial ash had lower PBC than those developed in airfall ash. In the latter soils, PBC was affected by degree of weathering. Multiple regression indicated that most variation in PBC was accounted for by citrate-dithionite minus pyrophosphate extractable Al, oxalate minus pyrophosphate extractable Al, and pyrophosphate extractable Fe. This suggests that allophane, crystalline and non-crystalline aluminium hydrous oxides, and Fe associated with organic matter, account for the predominant P-sorbing sites. The low EPC figures, which were correlated with Olsen extractable P, indicate potential P deficiency as a limitation to crop production.  相似文献   

16.
The adsorption of the silica in water by soils was investigated using principal river waters and soils collected in central Chile from about 34° to 41° south latitude. The adsorption of silica in water (y) was linearly proportional to the silica concentration in river waters (x) as shown by the following equation:

y=bx-a

where a and b were constants being subject to the nature of the soils. The silica contentration in river waters appeared to relate closely to the rocks in the catchment area. and was high in rivers from volcanic ash areas. However, the salt concentration had no correlation with the silica concentration, and tended to lower to the southward with an increase in annual precipitation and a decrease in annual mean temperature. Sulphate appreciably lowered the adsorption of silica by soils, although chloride and nitrate had little effect on the adsorption. The a-value, dissolution of silica in pure water, was the largest in paddy and alluvial soils, and both the a- and b-values were less in surface soils .in comparison with those of lower horizons. Soils caused neither adsorption nor dissolution of silica at a certain silica concentration. This silica zero adsorption concentration differed greatly from soil to soil, and the largest value which was observed in the surface soil of an irrigated paddy soil was so large that it could not adsorb silica from any river water in the central Chile. In contrast to this soil, an imogolitic subsoil of an Ando soil exhibited the highest adsorption concentration, i.e. it was possible to adsorb silica from every river water in the central Chile. Humus seemed to protect soil silica from dissolution and at the same time to prevent adsorption of silica by soils. Allophanic colloids were labile in water without humic-material, readily releasing silica into the water.  相似文献   

17.
The clay mineralogy of 22 samples of the Ap horizons of Ando soils was determined by a combination of methods. Of these samples, 15 did and 7 did not contain allophane and imogolite. Opaline silica was found in 4 samples, whereas aluminum—humus complexes, iron oxides and layer silicates were found in all samples. The presence of allophane and imogolite and the absence of opaline silica in a few Ap horizons was related to mixing of A1 horizons and subsoils by cultivation and to lower supplies of organic matter relative to the amounts of aluminum released from volcanic ash by weathering. The contents of 2:1 and 2:1:1 layer silicates and their intergrades were larger in soils in which quartz predominated in fine fractions. It was inferred that aluminum bound with humus and in allophane-like constituents, rather than aluminum in allophane and imogolite, is important in reactions with phosphate and fluoride.  相似文献   

18.
Geochemical sorption and biological demand control phosphorus (P) retention and availability in soils. Sorption and the biota predominantly utilize the same inorganic form of P, from the same soil pool, on the same time scale, and thus are likely to compete for P as it flows through the available pool. In tropical soils, P availability is typically quite low and soil geochemical reactivity can be quite high. We tested whether greater P sorption strength in tropical soils resulted in lower biological uptake of available P. Since the strength of soil sorption and biological demand for P change as ecosystems develop and soils age, we used soils from the two upper horizons from three sites along a 4.1 million-year-old tropical forest chronosequence in the Hawaiian archipelago. We evaluated the strength of geochemical sorption, microbial demand, and the partitioning of added available P into biological versus geochemical soil pools over 48 h using a 32PO4 tracer. Soil sorption strength was high and correlated with soil mineral content. The amount of added phosphate geochemically sorbed versus immobilized by microbes varied more between the organic and mineral soil horizons than among soil ages. Microbial activity was a good predictor of how much available P was partitioned into biological versus geochemical pools across all soils, while sorption capacity was not. This suggests that microbial demand was the predominant control over partitioning of available P despite changes in soil sorption strength.  相似文献   

19.
The horizons of different types in alluvial soils of central Russia are compared with respect to their morphological characteristics using the method of dendrograms. It is argued that diagnostic soil horizons should clearly reflect in their properties the character of pedogenic processes and, thus, be the basis for classification of alluvial soils. Overall, seven types of soil horizons are suggested as diagnostic horizons for flood-plain soils of the Russian Plain.  相似文献   

20.
ABSTRACT

The stability of black soil carbon in the deep layers of Japanese volcanic ash soil (i.e., buried A horizons) is often explained by its unique chemical (molecular structure) and physical (associated with short-range-order minerals) recalcitrance. However, the stability of black soil C in buried A horizons may be changed by labile C supply for soil microbes. Here, we hypothesized that the mineralization of black soil C in buried A horizons of Japanese volcanic ash soil could be easily accelerated by a supply of labile C (i.e., a priming effect; PE). To test our hypothesis, we investigated the direction and magnitude of the PE with a buried A horizon in Japan using 13C-labeled glucose (2.188 atom %) in a short-term (21 days) incubation study. We also investigated the effect of mineral nitrogen (N), which could contribute to microbial activity in this incubation study. We found that a positive PE occurred by glucose supply with (182%) or without (181%) mineral N input over the 21-day incubation, and its values were very similar to the PE ratios previously reported in other deep soils. The estimated mean residence time (MRT) of black soil C considering PE was clearly accelerated by glucose supply, regardless of mineral N input, compared with the initial soil MRT. These results strongly support our hypothesis that the mineralization rate of black soil C in buried A horizons is easily accelerated by a labile C supply, and it also demonstrates important implications for the effects of global warming on buried A horizons (e.g., increased root exudation, fine root biomass supply, and N deposition) in Japanese volcanic ash soils.  相似文献   

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