Volcanic ash additions control soil carbon accumulation in brown forest soils in Japan

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 (Al_ox) 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 Al_ox content with no gravel (H-Al_ox-NGv), high Al_ox with a high gravel content (H-Al_ox-Gv), moderate Al_ox (M-Al_ox), and low Al_ox (L-Al_ox), and then analyzed for carbon content, carbon amount, carbon stock, Al_ox amount and pyrophosphate extractable aluminum (Al_py) amount. The correlation between the carbon and Al_py amounts and the relationship between the Al_py and Al_ox 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 Al_ox 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-Al_ox-NGv = H-Al_ox-Gv > M-Al_ox > L-Al_ox. 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-Al_ox-NGv BFS. Our results suggest that volcanic ash additions control the soil carbon accumulation of forest soil in Japan.     

Oxalate-soluble compounds of Al, Fe, and Si in soils of cold humid regions as a function of weathering

Original and published data on the contents of X-ray amorphous oxalate-soluble compounds of Al, Fe, and Si in mesomorphic eluvial soils of cold, moderately cold, and moderately warm continental humid and semihumid regions are generalized. The groups of soils developed from mafic igneous, metamorphic, and pyroclastic rocks are considered. It is shown that the content of oxalate-soluble oxides (OSOx) in the horizons of their maximal accumulation varies from less than 1% to 20–30%; the Al_ox/Fe_ox ratio varies from 1 to 6.5. The leading factor dictating the amount and quality of the OSOx in the soils is the presence or absence of volcanic glass in the parent materials. The boundary between the soils with and without volcanic glass corresponds to the OSOx content of 5% and the Al₂O_3ox/Fe₂O_3ox ratio equal to 2. These criteria are more reliable than the Al_ox/Fe_ox ratio used by foreign soil scientists to specify Andosols (Al_ox/Fe_ox > 2). The contents of oxalate-soluble oxides of Al and Fe do not depend on the total contents of these oxides in the parent material and seem to be related to the presence of these elements in minerals with different resistance to weathering. Under the natural conditions described in this paper, the content of OSOx shows a very weak response to zonal (temperature-controlled) climatic changes and/or to changes in the degree of humidity and the continentality of the climate.     

General Chemical Properties of Brown Forest Soils Developed from Different Parent Materials in the Submontane Zone of the Kanto and Chubu Districts, Japan

It is essential to analyze chemical properties including the amount of various materials and the soil colloid characteristics in forest soils to forecast wood production and the distribution of and variations in the environmental functions of forest soils, such as conservation of stream water and carbon sequestration. Approximately 70% of the forest soils in Japan consists of Brown Forest Soils (BFS), which are considered to be typical zonal soils under the humid-temperate and warm-temperate regime of Japan. BFS were subclassifled into several groups according to the soil moisture environment along the slope and morphological properties. However, even the same type of soil may display different properties depending on the climatic conditions, parent materials and vegetation types. In the present study, the variations in the carbon content, nitrogen content, cation exchange capacity and some properties depending on the parent materials, were clarified by using 34 sola of BFS, and 3 sola of black soils (BLS) for comparison, which were distributed in the submontane zone of the Kanto and Chubu districts in central Japan under the same climatic conditions. We observed differences in the pH, cation exchange capacity, base saturation and clay content among BFS samples derived from various parent materials. The BFS derived from volcanic ash contained obviously larger amounts of carbon and nitrogen than the BFS derived from other parent materials. However, the BFS derived from volcanic ash differed from the BLS derived from volcanic ash in the vertical distribution pattern of carbon and nitrogen. Thus, even in the submontane zone of the Kanto and Chubu districts, the chemical properties of BFS varied considerably with the parent materials. It was concluded that the classification of BFS by the parent materials was useful for evaluating the ability of the BFS, that cover 70% of the forests in Japan, to store various materials.     

Assessing alternative approaches to predicting soil phosphorus sorption

Twenty‐five pasture soils were sampled from high‐rainfall zones of southeastern Australia to examine relationships between soil properties, and between soil properties and P buffering capacity (PBC) measures. Correlations between PBC values and soil properties were generally poor, with the exception of oxalate‐extractable Al (Al_ox) (r ≥ 0.97). Predictions of PBC were further improved when clay, as well as Al_ox, was included in a linear regression model (r² ≥ 0.98). When Al_ox and oxalate‐extractable Fe were excluded from the modelling exercise, a more complex three‐term linear regression model, including pH_H2O, exchangeable H and cation exchange capacity, adequately fitted both PBC values of the 25 soils examined in this study (r² ≥ 0.76). However, the Al_ox, Al_ox plus clay and the three‐term models gave poor predictions of the PBC values when the models were validated using 28 independent soils. These results emphasize the importance of model validation, because predictive models based on soil properties were not robust when tested across a broader range of soil types. In comparison, direct measures of PBC, such as single‐point P sorption measures, are more practical and robust methods of estimating PBC for Australian soils.     

火山岩海岛土壤硒元素空间分异及富集机制研究——以广西涠洲岛为例

选择广西北海涠洲岛作为研究区,网格化采集涠洲岛表层土壤样品106件、成土母岩16件,对亚热带环境下火山岩海岛土壤硒元素空间分布特征及赋存形态进行研究,并探讨其影响机制.结果表明,涠洲岛表层土壤中全硒自然变化范围为0.005～0.567 mg/kg,平均为0.287 mg/kg,足硒和富硒土壤占全岛总面积的70.87％....     

High gradient magnetic separation of some soil clays from Nigeria, Brazil and Colombia.

High gradient magnetic separation was used to fractionate the clay from some tropical soils. Acid-oxalate-extractable iron (Fe_ox) and aluminium (Al_ox) and total carbon were measured in the whole clay, the magnetic fraction and the tailings. The magnetic separation resulted in a wider range of concentrations of these elements than in the whole clays. In each of the clays Fe_ox was greater in the magnetic fraction than in the tailings; Al_ox was more variable. Carbon was also concentrated in the magnetic fraction suggesting that it is associated more with Fe_ox than Al_ox. The relationships between Fe_ox, Al_ox and carbon depend on soil classification and soil age.     

Phosphate sorption by Egyptian,Ethiopian and German soils and P uptake by rye (Secale cereale L.) seedlings

Phosphate sorption was studied in samples (0 - 20 cm depth) of five soils from Egypt (pH 7.4 - 8.7), four soils from Ethiopia (pH 3.9 - 5.3) and six soils from Germany (pH 3.3 - 7.2). Sorption parameters were calculated according to Pagel and Van Huay (1976) and according to Langmuir (Syers et al., 1973). Phosphate sorption parameters and oxalate extractable Fe and Al (Fe_ox, Al_ox) were related to the phosphate uptake by young rye plants in Neubauer pot experiments. P sorption parameter after Pagel and Van Huay (A) correlated significantly positively with the Fe_ox and Al_ox content in acid (r = 0.73) as well as in calcareous soils (r = 0.89) if the whole equilibrium concentration range (0 - 14 mg P/L) was considered. The relations calculated after Langmuir (B) were similar. P uptake by rye in acid soils was negatively correlated with the affinity constant n (r = ?0.76, (A)). In calcareous soils, a negative correlation between P uptake and affinity constant was calculated in the lower P equilibrium range (0 - 2.8 mg P/L) only for (B). Thus, P uptake decreased with increasing strength of P bonding to soil. From these results it is concluded that phosphate sorbed to Fe/Al oxides is an important P source for plants in acid and calcareous soils.     

Grade of weathering and fertility of volcanic ash soils of Aso volcano

Texture is one of the major criterions in soil classification, probably because it has a decisive influence on soil properties. This is particularly true for volcanic ash soils. Most ashes are largely composed of sand and silt particles with little clay (11, 15). The ash weathers very rapidly (1), and clay site particles less than 2 microns in diameter occur even within a few months, as shown by Ishii at the authors' laboratory. Those clay size particles produced in the early stage of weathering are slightly weathered ones (2), and are still subject to rapid weathering, losing bases and silica under humid and well drained conditions. In consequence the clay fraction of volcanic ash soils is composed of particles which vary in degree of weathering from slightly altered glass and feldspar to true clay mineraloids and minerals. The clay fraction of younger soils as a whole is less and that of older ones is more weathered. Weathering brings a remarkable change in the properties of volcanic ash soils; for example, an inerease in soil acidity, lowering of base saturation and bulk density, or accumlation of organic matter. These changes must exert a great influence on soil fertility directly or indirectly.     

Estimation of the phosphorus sorption capacity of acidic soils in Ireland

The test for the degree of phosphorus (P) saturation (DPS) of soils is used in northwest Europe to estimate the potential of P loss from soil to water. It expresses the historic sorption of P by soil as a percentage of the soil's P sorption capacity (PSC), which is taken to be α (Al_ox + Fe_ox), where Al_ox and Fe_ox are the amounts of aluminium and iron extracted by a single extraction of oxalate. All quantities are measured as mmol kg soil^?1, and a value of 0.5 is commonly used for the scaling factor α in this equation. Historic or previously sorbed P is taken to be the quantity of P extracted by oxalate (P_ox) so that DPS = P_ox/PSC. The relation between PSC and Al_ox, Fe_ox and P_ox was determined for 37 soil samples from Northern Ireland with relatively large clay and organic matter contents. Sorption of P, measured over 252 days, was strongly correlated with the amounts of Al_ox and Fe_ox extracted, but there was also a negative correlation with P_ox. When PSC was calculated as the sum of the measured sorption after 252 days and P_ox, the multiple regression of PSC on Al_ox and Fe_ox gave the equation PSC = 36.6 + 0.61 Al_ox+ 0.31 Fe_ox with a coefficient of determination (R²) of 0.92. The regression intercept of 36.6 was significantly greater than zero. The 95% confidence limits for the regression coefficients of Al_ox and Fe_ox did not overlap, indicating a significantly larger regression coefficient of P sorption on Al_ox than on Fe_ox. When loss on ignition was employed as an additional variable in the multiple regression of PSC on Al_ox and Fe_ox, it was positively correlated with PSC. Although the regression coefficient for loss on ignition was statistically significant (P < 0.001), the impact of this variable was small as its inclusion in the multiple regression increased R² by only 0.028. Values of P sorption measured over 252 days were on average 2.75 (range 2.0–3.8) times greater than an overnight index of P sorption. Measures of DPS were less well correlated with water‐soluble P than either the Olsen or Morgan tests for P in soil.     

Potential Iron and Phosphate Mobilization During Flooding of Soil Material

This study shows that mobilization of phosphate from soils under anaerobic conditions can be intimately coupled with reductive dissolution of iron from iron oxides. Among four soil samples from the reclaimed Skjernå estuary in Denmark incubated anaerobically and amended with glucose, 28–39% of the dithionite-citrate-bicarbonate-extractable iron and 10–25% of the oxalate-extractable phosphorus (P_ox) were released to the soil solution after 31 days. Significant correlation (r = 0.992**) between the molar ratio P_ox/(Fe_ox + Al_ox) for the aerobic samples and (P_{P sol}/Fe_sol) (the molar ratio between phosphate and iron in solution during anaerobic incubation), indicates that the phosphate saturation status of the soil is an important determinant of the amount of phosphate released during flooding of moderately acid soils.     

Field and chemical Evaluation of volcanic ash deposition in some soils of Malaysia

A study was conducted to determine the extend of volcanic ash deposition and distribution in some soils of Malaysia. A total of 12 soil types of different geology and locations from Peninsular Malaysia and West Sarawak were collected and analysed for their physico‐chemical and dissolution analysis. All soils under study belonged to either the order of Inceptisols, Ultisols or Oxisol. They were acidic and had relatively low CEC and exchangeable bases. The Al saturation percent were higher in the Ultisols as compared to the Oxisols. Field and laboratory investigations, and the dissolution analysis comprising of the binary ratio, ferrihydrite percent and allophane content, suggested that the soils under study were highly weathered and non‐allophanic. The soils of West Sarawak, however, may contain a reasonable deposits of the volcanic ash materials, as shown by the higher pH_NaF values of near 9.4, but other laboratory analysis were still not conclusive of the result.     

Influences of aluminum ions on the determination of zpc (zero point of charge) of variable charge soils

Influence of Al dissolution on soil ZPC (zero point of charge) measured by a potentio-metric titration (PT) method and a modified salt titration (STPT) method was examined using two strongly weathered soils from Thailand and two volcanic ash soils from Japan. The amount of dissolved Al ions increased with the increase in the concentration of a supporting electrolyte for the strongly weathered soils, while the increase was negligible for the volcanic ash soils.

ZPC value of the strongly weathered soils determined by the PT method was lower than that by the STPT method, due to the greater Al dissolution associated with the higher electrolyte concentration used in the PT method. Al ions adsorbed onto the soil surface would shift the ZPC to a higher pH value not as a result of the formation of hydroxy Al polymers, but due to the blocking of permanent negative charge sites, which could otherwise lower the ZPC. The σp value, as a measure of permanent charge or the amount of 11 or O11 adsorbed by a soil required to attain the ZPC, could be used to describe this phenomenon.

In the STPT method, the salt concentration was not high enough to causc a significant Al dissolution at the ZPC, which is considered to be a more suitable condition than in the PT method because the ZPC value can be evaluated at a low salt concentration as in the ease of field conditions for crop production. Thus, the STPT method is rccommendcd for the determination of the ZPC.     

Comparison of different models for phosphate sorption as a function of the iron and aluminium oxides of soils

Phosphate sorption on topsoil and subsoil samples from different soils located in the eastern part of Germany was studied. Two models were fitted to sorption data obtained after 4 and 40 d of gentle shaking. The models differ with respect to the fractions of iron and aluminium (hydr)oxides that are considered and whether the phosphate initially sorbed in the soil is taken into zccount. Oxalate-extractable P, (P_ox), appears to be a major part of the total soil P. The total P sorption measured, F, was predominantly related to the amounts of amorphous iron (Fe_ox) and aluminium (Al_ox). A significant relation between crystalline iron (Fe_d– Fe_ox) and total P sorption was not found. Reversibly adsorbed phosphate (P_i), measured after 40 d reaction time, was a function of clay content and content of amorphous iron and aluminium (hydr)oxides.     

Semiquantitative determination of imogolite and Al-rich allophane (Si / Al ≃ 1 : 2) in some volcanic ash soils in San'in region by a combination of thermogravimetry-differential thermal analysis and trimethylsilylation analysis of soil clays

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 (= Si_o) 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.     

Studies on the volcanic ash soils in the environs of Mt. Daisen

The environs of Mt. Daisen, Tottori Prefecture, are generally mountainous or hilly, and apart rom small areas of alluvial and coastal flats there is little level ground. The volcanic ash soils derived from the quartz biotite hornblende andesitic ejecta occur on the gently undulating foot-hill and on the level ground with exception of alluvial flats. Considering the fact that these soils were formed from not only volcanic ash but the coarser materials, they may be properly called volcanogenous soils. The volcanic ejecta have been deposited on the soils from diluvial series, andesite, basalt, granite, and tertiary sedimentary rocks. It was recognized that in an eruption the large ejecta, such as fine porous pumiceous lapiili descended first, then the smaller Particles such as sands, and finally the smallest, as ashes. All of these deposits have been highly weathered, but the quartz and hornblende remain in a fresh state¹⁾. The author has studied some characteristics of these volcanic ash soils.     

Classification of anthrosols with vitric/andic properties derived from lignite ash

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, Al_o+0.5 Fe_o, and P-retention, as they serve as diagnostic criteria to define either vitric or andic horizons. For Al_o+0.5 Fe_o, 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.     

Resistance of mineral soils to Fe(III) reduction

Gleying and enhancement of hydromorphism in wetland soils due to Fe(III) reduction entail a series of degradation processes. The resistance of wetlands to degradation can be calculated from the content of potentially reducible iron, Fe(III)_pr, which is found from the van Bodegom equation taking into account the contents of oxalate-soluble iron Fe_ox and dithionite-soluble iron Fe_dit in the soil. In addition, this makes it possible to distinguish relict and actual gleysols. The van Bodegom equation is applicable to soils from which the oxalate solution extracts only amorphous and poorly crystallized iron compounds, which are quickly reduced by Fe-reducing bacteria. These soils have a low proportion of Fe(II) (no more that 15% of the total iron), as well as an accumulative profile distribution of Fe_ox. The van Bodegom equation is unsuitable for calculating the Fe(III)_pr content in soils with a high proportion of Fe(II) and a nonaccumulative profile distribution of Fe_ox.     

Soils of slopes and bottomland positions of the small stream valley in the central forest reserve: Chemical properties and clay mineralogy

Pale-podzolic soils occupying slope positions in a small stream valley are more acidic and contain less pedogenic chlorites in the clay fraction than those soils occupying uplands. These characteristics are thought to be caused by more intensive leaching of matter from eluvial horizons due to intensive lateral interflow of soil water. Soddy-gleyic soils of the stream bottomland are rich in organic matter and have a slightly acidic reaction in the A1 horizon and an alkaline reaction in the calcareous subsoil. Both factors lead to accumulation of Fe_ox and Al_ox supplied to bottomland positions from uplands and slopes and those formed in situ.     

Microbial ecology in tea soils

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.     

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。