Non-volcanic Soils Research Articles

Perspective of soil carbon sequestration in Chilean volcanic soils

We analysed a large dataset consisting of 457 soil profiles of Andisols and Ultisols of volcanic origin compared to 60 non-volcanic soils. We hypothesised that soil pH has a greater impact on the development of Al-organomineral complexes in volcanic soils compared to non-volcanic soils, in the latter, the silt and clay fractions play a crucial role. Soil pH >4.5 strongly influenced the formation of Al-organomineral complexes in volcanic soils, while an increase in allophane content led to a decrease in SOC. Ultisols with more crystalline clays, such as halloysite and disordered kaolinite, the pH had a weaker impact and there was no effect on non-volcanic soils. Instead, a positive correlation (R2 = 0.63, p < 0.01) was found between silt and clay and SOC in non-volcanic soils, supporting our second hypothesis. Soil pH played a significant role in the interplay between Al-organomineral complexes and allophane formation, while crystalline mineralogy has a direct effect on SOC levels in non-volcanic soils.

Effects of soil and phylogeny on sulfur and phosphorus concentrations in wild plants on volcanic and non-volcanic soils in Japan

ABSTRACT Andosols are soils characterized by relatively high sulfur concentrations, but also by their low phosphorus availability for crops and vegetables. We assessed the effect of soil type on the concentrations of sulfur and phosphorus in plants using handheld X-ray fluorescence (XRF) analysis on herbarium specimens collected from Andosols and non-volcanic soils in Japan. The sulfur concentrations in plants from Andosols were higher than plants from non-volcanic soils, but there was no significant difference between their foliar phosphorus concentrations. Only three specimens out of 1203 herbarium specimens were below the sulfur concentration (1000 mg kg−1) needed for adequate growth of crops, but about half of specimens were below that for phosphorus (2000 mg kg−1). The sulfur concentrations were high in herbaceous plants, especially in plants from the Brassicaceae and Liliaceae families. Overall, the results show that the sulfur concentrations in wild plants from Japan were higher in Andosols, with a low risk for sulfur deficiency. In contrast, the effect of soil type on the phosphorus concentrations in plants was small, and this may be explained because most wild plants grow under phosphorus-limiting conditions. Finally, the analysis reveals a strong correlation between sulfur and phosphorus concentrations in plants, suggesting the existence of a mechanism that controls the sulfur and phosphorus concentration ratios.

Upper limit of mineral-associated organic carbon in temperate and sub-tropical soils: How far is it?

Soil organic carbon (SOC) is the main terrestrial C pool and is roughly divided into stable mineral-associated organic carbon (MAOC) and particulate organic matter carbon (POC). However, the sequestration capacity of MAOC remains unquantified. Currently, soils are considered to have a limited capacity to accumulate MAOC, primarily due to the presence of fine fractions, i.e. silt and clay particles. However, it is unlikely that saturation will occur in all soils due to land use. Therefore it is necessary to investigate whether soils from different latitudes and their silt and clay fractions that comprise MAOC are saturated. We selected 71 soil samples that were physically fractionated from a Mexican inventory of vegetation with a wide range of SOC (4–186 g kg−1 soil) and clay (126–777 g kg−1 soil) contents. Soils were grouped into non-volcanic soils and allophanic Andosols. In the first group, we found a positive and highly significant linear relationship between SOC and MAOC contents, but no upper limit was detected. We found a common slope of 0.86 (R2 = 0.97, p < 0.01), i.e. 86% of the SOC was contained in MAOC irrespective of soil types and management, a value very similar to that in other studies. Conversely, for allophanic Andosols, which had SOC content twice that of non-volcanic soils, a second-order polynomial function (R2 = 0.98, p < 0.01) was established, the upper limit of which exceeded 186 g SOC kg−1 for a MAOC of 134 g kg−1. This was also supported by an increasing polynomial function of particulate organic carbon (POC) as the SOC increased. In both types of soils, maximum MAOCs were found between 700 and 800 g kg−1 of silt and clay in medium-textured soils. The amount of silt and clay particles was limited by SOC accumulation in the silt fraction as clay became saturated. These results are influenced by the mass proportion of silt and clay that follows a unique pattern in allophanic Andosols and non-volcanic soils. An investigation of a comprehensive database comprising 21,315 soil profiles sampled 0–30 cm across Mexico showed that most soils are below 186 g SOC kg−1 the bending point above which the upper limit does exist.

Effect of surfactants on the sorption-desorption, degradation, and transport of chlorothalonil and hydroxy-chlorothalonil in agricultural soils

The fungicide chlorothalonil (CTL) and its metabolite hydroxy chlorothalonil (OH-CTL) constitute a risk of soil and water contamination, highlighting the need to find suitable soil remediation methods for these compounds. Surfactants can promote the bioavailability of organic compounds for enhanced microbial degradation, but the performance depends on soil and surfactant properties, sorption-desorption equilibria of contaminants and surfactants, and possible adverse effects of surfactants on microorganisms. This study investigated the influence of five surfactants [e.g., Triton X-100 (TX-100), sodium dodecyl sulphate (SDS), hexadecyltrimethylammonium bromide (HDTMA), Aerosol 22 and Tween 80] on the sorption-desorption, degradation, and mobility of CTL and OH-CTL in two volcanic and one non-volcanic soil. Sorption and desorption of fungicides depended on the sorption of surfactants on soils, surfactants' capacity to neutralize the net negative charge of soils, surfactants’ critical micellar concentration, and pH of soils. HDTMA was strongly adsorbed on soils, which shifted the fungicide sorption equilibria by increasing the distribution coefficient (Kd) values. Contrarily, SDS and TX-100 lowered CTL and OH-CTL sorption on soils by decreasing the Kd values, which resulted in an efficient extraction of the fungicide compounds from soil. SDS increased the degradation of CTL, especially in the non-volcanic soil (DT50 values were 14 and 7 days in natural and amended soils, with final residues <7% of the initial dose), whereas TX-100 enabled an early start and sustenance of OH-CTL degradation in all soils. CTL and OH-CTL stimulated soil microbial activities without noticeable deleterious effects of the surfactants. SDS and TX-100 also reduced the vertical transport of OH-CTL in soils. Results of this study could be extended to soils in other regions of the world because the tested soils represent widely different physical, chemical, and biological properties.

Mineral characteristics of volcanic ash‐derived soils affecting boron adsorption

AbstractVolcanic ash‐derived soils are naturally deficient in the essential micronutrient B, but they also have maximum adsorption capacities (bB) that are as much as 40 times greater than in nonvolcanic soils, further exacerbating B availability. Because short‐range‐order (SRO) aluminosilicates (allophane and imogolite) and iron (Fe) oxyhydroxides are the main clay‐sized minerals in these soils, we hypothesized that their relative abundances would explain variations in boron sorption capacity (bB). We characterized 23 volcanic ash‐derived soils (Andisols and non‐Andisols) from the Pacific coastal plain of Guatemala by X‐ray diffraction, oxalate and pyrophosphate extractions, and thermal analysis, with four selected soils further examined by Mössbauer spectroscopy (MBS). Only soils with andic character (high SRO Si–Al content) contained considerable amounts of imogolite, with allophane in the clay fraction. Overall, soil SRO Al–Si phases were strongly correlated with clay B adsorption capacity (R = 0.65, p &lt; 0.001) and clay specific surface area (R = 0.88, p &lt; 0.001) suggesting that SRO Al–Si phases are the dominate influence on B behavior in these soils. Fe mineral composition was dominated (39%–71% of total Fe) by SRO Fe(III) oxyhydroxides (nanogoethite and ferrihydrite) of various crystallinities. In low allophane soils, SRO Fe phase abundance correlated with bB as did the abundance of low crystallinity kaolinite phases, suggesting these phases are important when SRO Si–Al content is low. Any efforts to predict B behavior or plan soil fertility treatments in volcanic‐influenced soils needs to consider the impact of SRO phases.

The mass water content of paddy soil after harvest is strongly associated with the accumulation of organic matter as the source of available nitrogen

ABSTRACT Paddy soils are the dominant source of nitrogen for rice via mineralization, and knowledge about the available nitrogen (AN) in paddy soil is important for rice cultivation. Although the relationship between AN and soil physicochemical parameters has been studied, no systematic studies of the relationships between AN and the soil moisture content of various soil types in Japan have been studied. Therefore, we examined the impacts of soil types and treatment of organic matter application or paddy–upland rotation on these relationships. We sampled topsoils from 30 paddy fields throughout Japan. We compared the relationships between AN and soil physicochemical properties, such as total nitrogen (TN), cation exchange capacity, soil water-holding capacity (WHC), mass water content after harvest (MWH), and water content after harvest (WCH). The scatter diagram revealed that AN and either MWH or WCH (p < 0.01) had the highest positive linear correlation coefficient; the pattern became clearer after separating Andosols and non-Andosols. We analyzed the relationship between AN and either TN or MWH in 100 topsoils, including soils from treatment plots with successive organic matter application or paddy-upland rotation. A significantly positive correlation between AN and TN was observed, although the regression slopes for volcanic or non-volcanic soils differed. The decrease in AN due to frequent paddy–upland rotation was greater than that for TN. On the other hand, a highly positive correlation between AN and MWH was observed, and the coefficient of determination was higher than that for AN and TN. TN and the WHC increased when the accumulation of organic matter in paddy soil was greater. As there was a positive correlation between WHC and MWH, a positive correlation was also observed between AN and MWH. Additionally, we investigated year-to-year variation in MWH using topsoil samples collected before autumn tillage, for 3–5 consecutive years in 24 plots, for various soil types throughout Japan. In order to eliminate the effects of precipitation and to minimize the fluctuation of MWH in paddy topsoil, it was desirable to collect topsoil samples within 24–96 hours of the last precipitation of 1 mm h−1 or more, for the measurement of moisture content.

五大连池火山土壤细菌多样性及其群落结构

火山熔岩生境孕育了独特的土壤微生物群落。为了解火山生态系统土壤细菌群落多样性和群落结构及其关键影响因子，选择五大连池新、老期火山为研究样点，非火山为对照，基于高通量测序方法，分析不同采样点土壤细菌群落结构和多样性，结合土壤理化指标，进一步分析影响火山生态系统土壤细菌群落多样性的环境因子。结果表明：细菌操作分类单元（OTUs）、Ace指数、Chao1指数和Simpson指数变化趋势一致，表现为非火山 > 新期火山 > 老期火山。三个样点土壤的共有OUTs数量为713个，各自特有的OTUs数量不尽相同。三个样点土壤中检测到共有细菌16个类群，其中变形菌门、酸杆菌门、放线菌门和绿弯菌门为优势菌群，老期火山土壤中酸杆菌门、疣微菌门、Rokubacteria相对丰度最大，而Patescibacteria相对丰度最小。三个样点的土壤细菌群落具有明显的空间关系，相似性差异较大，但不符合随地理距离的增加而降低的模型。土壤理化性质测定结果标明：老期火山土壤pH、有机质、全氮、全磷、铵态氮和硝态氮显著高于新期火山和非火山，新期火山土壤含水量和速效磷显著低于老期火山和非火山。喷发时间和火成岩基质等特性会导致不同火山土壤理化性质的差异，进而影响土壤细菌多样性和群落结构。Pearson相关性分析表明：土壤pH显著影响细菌的多样性指数。冗余分析（RDA）结果表明：土壤氮含量、pH和有机质是影响火山森林生态系统土壤细菌群落结构的主要因子。;Volcanic lava habitats breed unique soil microbial communities. Soil bacterial diversity, community structure, and key factors influencing volcanic ecosystems were explored using soil microorganisms in new volcano soils and old volcano soils in Wudalianchi, Heilongjiang Provice. Non-volcano soils were used as the control. Using the Illumina high-throughput sequencing method, we analyzed soil bacterial community structure and diversity at three sampling sites. Combined with soil physical and chemical characteristics, environmental factors affecting the diversity of soil bacterial community in a volcanic ecosystem were analyzed. Results showed that the operational taxonomic units (OTUs) and the diversity index (the Ace index, the Chao 1 index, and the Simpson index) of bacteria presented the same trends and followed the order Non-volcano > new volcano > old volcano. The number of OTUs unique to new volcano soils, old volcano soils and Non-volcano soils were 852, 820, and 879 respectively, as well as the number of their common OTUs was 713. The three plots soils contained same 16 kinds of bacterial groups, and Proteobacteria, Acidobacteria, Actinobacteria, and Chloroflexi were the most dominant bacteria groups. Acidobacteria, Verrucomicrobia, and Rokubacteria had the highest relative abundances, whereas Patescibacteria had the lowest in the old volcanic soils. In the three plots, the soil bacterial communities had obvious spatial relationships, and their similarity in community structure varies greatly, It did not conform to the model of beta diversity, which similarity in bacterial composition gradually decreased with increasing geographical distance. We think it could be related to the volcanic eruption characteristics or magma composition. The obtained soil physicochemical properties indicated that soil pH, Soil organic matter (SOM), total nitrogen (TN), total phosphorus (TP), ammonium nitrogen (AN), and nitrate nitrogen (NN) in old volcanic soils were significantly higher than those in the new volcanic soils and non-volcanic soils, while water content and available phosphorus in the new volcanic soils were significantly lower than those in the old volcanic soils and non-volcanic soils. Volcanic eruption is a form of violent large-scale disturbance, the volcanic characteristics of eruption time and igneous rock led to differences among volcanic soils at different stages, and further led to differences among soil bacterial diversity and community structure. Pearson correlation analysis showed that soil pH significantly affected the Simpson index, the Ace index and the Chao 1 index of soil bacteria. The redundancy analysis (RDA) showed that soil nitrogen, soil pH, and SOM were the crucial factors affecting the bacterial community structure of the Wudalianchi volcanic ecosystem.

Volcanic deposits affect soil nitrogen dynamics and fungal–bacterial dominance in temperate forests

Volcanic deposits increase soil organic carbon storage. However, little is known about the effect of volcanic deposits on forest soil nitrogen (N) dynamics and microbial communities. We explored gross and net N transformation rates and microbial community structure using a phospholipid fatty acid (PLFA) method across eight forests with soils derived from different parent material in Japan. Volcanic mineral soils had approximately three-fold greater total N and inorganic N contents and gross nitrification, ammonium immobilization, and nitrate immobilization rates that were one order of magnitude higher than in non-volcanic soils. Moreover, volcanic mineral soils had a 1.7-fold lower N turnover rate, which was estimated as net N mineralization rate per soil N. This was likely caused by a higher gross N immobilization rate, potentially due to the mineral traits of volcanic soils. Volcanic mineral soils had approximately four- and three-fold greater microbial biomass-N and bacterial PLFA contents, respectively, and the fungal:bacterial PLFA ratio was lower in volcanic mineral soils than in non-volcanic soils. Microbial community structure, analyzed using non-metric multidimensional scaling, was distinct between volcanic and non-volcanic soils, and was significantly affected by soil characteristics. This study demonstrates that aside from soil carbon storage, volcanic deposits are related to increases in soil N immobilization, N content, bacterial biomass, and N transformation rates in forest ecosystems.

Conditions favoring local podzolization in soils developed from flysch regolith – A case study from the Bieszczady Mountains in southeastern Poland

Podzolization occurs mainly in soils developed from highly leached and coarse-textured parent materials in areas that remain under the influence of humid climate conditions and where forest or heath vegetation supply enough organic matter to form organic horizons on the surface of mineral soils. However, in certain environmental conditions Podzol development was found also in extremely unfavorable types of parent material, e.g. ultramafic rocks or even regoliths containing carbonates. Flysch rock regolith found in many geographic regions is an example of soil parent material considered to be unfavorable for podzolization in its major part due to its high clay, Ca, and Mg contents. Areas formed of materials considered to be rather unfavorable to Podzol development but characterized by very local occurrence of podzolized soils may be helpful in assessing the factors which favor the occurrence of this process and its thresholds. The main objective of the present study was to determine an optimal combination of conditions that trigger podzolization in soils in the uppermost part of mid-mountain slopes formed of flysch rocks in the Bieszczady Mountains in southeastern Poland. At the same time, an attempt was made to determine pedogenic thresholds of local podzolization in soils in the studied area. The studied soils showed large variability in soil processes and were classified according to the WRB as four different Reference Soil Groups: Podzols, Cambisols, Umbrisols and Leptosols. Two out of the eight soil profiles exhibited well-developed spodic horizons, while the properties of the two other profiles may be explained by either cryptopodzolization and/or formation of andic properties in non-volcanic soil material. Evidence of podzolization was observable in changes in soil morphology (i. e. color and consistence of soil material), vertical distribution of labile C and Fe and Al pedogenic forms, changes in mineral composition (mainly dissolution of chlorite, formation of mixed layered clay minerals and the redistribution of various amorphous phases), and also micromorphological features (presence of monomorphic fine coatings consisting of Fe- and Al-organic compounds). However, the occurrence of Podzols was strongly limited across the study area and determined by a combination of environmental conditions such as the co-occurrence of four key factors: (1) humid and cool climate, (2) sandy texture and mineral composition of parent material dominated by quartz, (3) location on the uppermost part of consequent slopes (ridge crests) and (4) predominance of berry (Vaccinium sp.) thickets in the vegetation cover in tandem with the occurrence of mosses (Polytrichum strictum and Sphagnum sp.). Moss cover facilitated a pedogenic feedback setup by increased water storage which promoted more advanced weathering and increase in dissolved organic carbon content in the soil. In the consequence the pedogenic threshold of podzolization was crossed.

Variation of Greenhouse Gases Fluxes and Soil Properties with Addition of Biochar from Farm-Wastes in Volcanic and Non-Volcanic Soils

The decomposition of organic wastes contributes to greenhouse gas (GHG) emissions and global warming. This study evaluated the effect of biochar (BC) produced from different farm wastes (chicken, pig and cow manures) on greenhouse gas emissions and soil chemical and biological properties in different grassland soils (volcanic and non-volcanic soils). A 288-day laboratory experiment was carried out, monitoring CO2, N2O and CH4 emissions and evaluating total C, soil pH, microbial biomass and enzymatic activity in three grassland soils. The results varied depending on the soil type and feedstock of BC produced. BC-cow decreased emissions of CO2 and CH4 fluxes for volcanic and non-volcanic soils, probably due to decreases in β-glucosidase activity. Biochars from cow and pig manures increased soil C content, favouring the persistence of C into the soil at 288-days of incubation. Soil pH increased with the application of BC in the soils.

Degradation kinetics of chlorpyrifos and diazinon in volcanic and non-volcanic soils: influence of cyclodextrins.

The intensive use of insecticides such as chlorpyrifos (CPF) and diazinon (DZN) in the agricultural activities worldwide has produced contamination of soils and/or transport to non-target areas including their distribution to surface and groundwaters. Cyclodextrins (CDs) have been proposed as an alternative in remediation technologies based on the separation of contaminants from soils because they could allow a higher bioavailability for their degradation with a low environmental impact. In this work, the degradation pattern of CPF and DZN and the formation and dissipation of the major degradation products 3,5,6-trichloro-2-pyridinol (TCP) and 2-isopropyl-6-methyl-4-pyrimidinol (IMPH) was established in four agricultural volcanic and non-volcanic soils belonging to Andisol, Ultisol, and Mollisol orders. Both pesticides were highly adsorbed in these soils, consequently, with a greater probability of contaminating them. In contrast, the adsorption of their two main metabolites was low or null; therefore, they are potential groundwater contaminants. The degradation processes were studied in the natural and amended soils with β-cyclodextrin (β-CD) and methyl-β-cyclodextrin (Mβ-CD) for CPF and DZN, respectively. A slow degradation of CPF and DZN was obtained for volcanic soils with observable residues until the end of the incubation time (150-180days). In Mollisols, the higher degradation rate of CPF was favored by the neutral to basic pH, and for DZN it was related to the lower adsorption and higher bioavailability. The amendment of soils with CDs produced slower degradation rates which led to a greater concentration of the compounds at the end of the incubation time. This effect was more pronounced for DZN. The exception was the Andisol, with no significant changes for both compounds regarding the unamended soil. No residues of TCP were observed for this soil in both conditions during the whole incubation time; nevertheless, the accumulation of TCP was significant in the Ultisol and Mollisols, but the concentrations were lower for the amended soils. The accumulation of IMPH was important in Mollisol amended soils; however, their residues were observed in the volcanic soils during the whole incubation period in the natural and amended soils. An important enhancement of the microbial activity occurred in the system β-CD/CPF in Mollisols, without a more effective degradation of the insecticide. The opposite effect was observed in the system Mβ-CD/DZN mainly in the oxidative activity in all soils. The higher degradation of DZN and IMPH in natural Mollisols was related to the higher hydrolytic and oxidative activities. The stability of the inclusion complexes formed could play an important role for explaining the results obtained with the amendments.

Soil properties and debris flows in Italy: potential relationships

Debris flows are known to be very dangerous hazards that can produce fatalities and severe damages. In the Campania region they involve Andosols with a unique set of morphological, chemical, physical, and hydrological properties that give them high fertility but, at the same time, high fragility as concerns land degradation processes, such as erosion and landslides. Because of the shallow character of some debris flows (e.g. Campania), they can strongly involve and evolve in and over the soil cover. Therefore, a better understanding of the soil properties is crucial in an integrated approach finalized to evaluate the landslide susceptibility of mountain ecosystems. The aim of this work is to investigate the soil (chemical, physical, and hydrological) properties of the detachment areas of eight debris flows occurred in non-volcanic mountain ecosystems (NVME) of Italy in the last 70 years. In this framework, we will mainly focus on the assessment of the soil andic properties, in order to verify if in the studied landscapes the debris flows involve soils characterised by these properties, as it happens in the Campania region.The analyzed events occurred on moderate to high slope gradient (ranging from 25° and 50°) and at different altitudes. Despite the lithological heterogeneity of the bedrock, the analyzed soils show remarkably similar features. Specifically, soils are generally deep and characterized by well developed topsoils, demonstrating that investigated sites were not subjected to intense erosion, which would have been expected considering the slope gradient. Moreover, these soils are markedly chemically and physically fertile, as indicated by the high organic carbon content and the prevalent loamy texture. As concerns the soil type, the preliminary analyses show that the investigated non-volcanic soils have andic and vitric features (except for Ceriana).These findings shed new light on the similarity of the materials involved by debris flows both in volcanic and non-volcanic mountain ecosystems of Italy, suggesting a pedological control on the debris flow hazard.

Multi-site monitoring for $$\hbox {N}_2\hbox {O}$$ N 2 O emission factors of synthetic fertilizer in various soils with different redoximorphic features across Japan

The use of N fertilizers for agricultural production acts as a sources of atmospheric $$\hbox {N}_2\hbox {O}$$ . Fertilizer induced $$\hbox {N}_2\hbox {O}$$ emission considerably varies in accordance with environmental factors. We conducted a $$\hbox {N}_2\hbox {O}$$ flux measurement campaign across 10 different experimental sites with various soil types throughout Japan and investigated the fertilizer induced $$\hbox {N}_2\hbox {O}$$ emission factors (FIEFs) of synthetic fertilizers (mainly urea) in multiple growing periods at each experimental site. FIEFs considerably varied among the 10 sites, and measurement periods ranged from 0.00 to 7.13 % in 40 total observations. Soil profile information divided the experimental sites into two major groups through cluster analysis, which are volcanic or non-volcanic soils. According to this classification, FIEFs were clearly differentiated into high and low FIEF groups (mean values: 2.67 and 0.59 %, respectively). Regression trees selected total soil carbon, the depth to the Fe mottling horizon, and mean air temperature as the key parameters to determine the strength of FIEFs out of 10 explanatory variables (e.g., N fertilizer application rates, fertilizer application times, clay content, total precipitation during measurement periods, pH, total soil carbon, and total soil nitrogen). The existence of shallow Fe mottling layer (up to 42.5 cm) induced high FIEFs in this model, suggesting that upward $$\hbox {N}_2\hbox {O}$$ emissions derived from the intermediate Fe mottling layers presumably contributed high $$\hbox {N}_2\hbox {O}$$ emissions in such soils. Our results suggest that the soil profile information associated with the water regime is an important index for synthetic fertilizer induced $$\hbox {N}_2\hbox {O}$$ emissions.

Kinetics of potassium release in sweet potato cropped soils: a case study in the highlands of Papua New Guinea

Abstract. The present study attempts to employ potassium (K) release parameters to identify soil-quality degradation due to changed land use patterns in sweet potato (Ipomoea batatas (L.) Lam) farms of the highlands of Papua New Guinea. Rapid population increase in the region increased pressure on the land to intensify subsistence production mainly by reducing fallow periods. Such continuous cropping practice coupled with lack of K fertilization practices could lead to a rapid loss of soil fertility and soil-resource degradation. The study aims to evaluate the effects of crop intensification on the K-release pattern and identify soil groups vulnerable to K depletion. Soils with widely differing exchangeable and non-exchangeable K contents were sequentially extracted for periods between 1 and 569 h in 0.01 M CaCl2, and K-release data were fitted to four mathematical models: first order, power, parabolic diffusion and Elovich equations. Results showed two distinct parts in the K-release curves, and 58–80% of total K was released to solution phase within 76 h (first five extractions) with 20–42% K released in the later parts (after 76 h). Soils from older farms that were subjected to intensive and prolonged land use showed significantly (P &lt; 0.05) lower cumulative K-release potential than the farms recently brought to cultivation (new farms). Among the four equations, first-order and power equations best described the K-release pattern; the constant b, an index of K-release rates, ranged from 0.005 to 0.008 mg kg−1 h−1 in the first-order model and was between 0.14 and 0.83 mg kg−1 h−1 in the power model for the soils. In the non-volcanic soils, model constant b values were significantly (P &lt; 0.05) higher than the volcanic soils, thus indicating the vulnerability of volcanic soils to K deficiency. The volcanic soils cropped for several crop cycles need immediate management interventions either through improved fallow management or through mineral fertilizers plus animal manures to sustain productivity.

Sorption-desorption behavior of pesticides and their degradation products in volcanic and nonvolcanic soils: interpretation of interactions through two-way principal component analysis.

Sorption-desorption behavior of six pesticides and some degradation products was assessed on seven agricultural volcanic and nonvolcanic soils belonging to Andisol, Ultisol, Mollisol, and Alfisol orders. The global interpretation of sorption data was performed by principal component analysis. Results showed exceptionally high sorption of glyphosate and aminomethylphosphonic acid (AMPA) (the breakdown product) on volcanic soils (K f > 1500μg(1 - 1 / n) mL(1 / n) g(-1)) related mainly to contents of amorphous aluminum oxides (Andisols) and crystalline minerals (Ultisols). The lower sorption on nonvolcanic soils was associated to low organic matter contents and lack of significant minerals. Metsulfuron-methyl and 3,5,6-trichloro-2-pyridinol (metabolite of chlorpyrifos) were weakly to substantially sorbed on Andisols and Ultisols, but the first one was not sorbed at pH > 6.4, including nonvolcanic soils. The metabolite of diazinon, 2-isopropyl-4-methyl-6-hydroxypyrimidine, was weakly sorbed on all soils (K f = 0.4 to 3.6μg(1 - 1 / n) mL(1 / n) g(-1)). Acidic compounds would be lixiviated in Mollisols and Alfisols, but they could leach also in Andisols and Ultisols if they reach greater depths. Atrazine and deethylatrazine sorption was related to organic carbon content; therefore, they were weakly retained on nonvolcanic soils (K f = 0.7 to 2.2μg(1 - 1 / n) mL(1 / n) g(-1)). Chlorpyrifos was highly sorbed on all soils reaching K OC values of >8000. Finally, the significant retention of chlorothalonil and diazinon on Mollisols and Alfisols in spite of their low OC contents showed the contribution of clay minerals in the sorption process.

Evidence of aggregate hierarchy at micro- to submicron scales in an allophanic Andisol

Aggregate hierarchy, a fundamental soil feature controlling various physical and biogeochemical processes, is well-studied for soils dominated by crystalline minerals but not for the soils rich in poorly-crystalline or short-range-order (SRO) minerals. We examined the presence and nature of aggregate hierarchy in the surface horizon of an Andisol which is characterized by high concentrations of organic matter and SRO minerals (esp. allophane/imogolite). Several pretreatments were tested to achieve maximum dispersion and the particle-size fractions isolated (<0.2 up to >53μm) were characterized by SEM, XRD, and elemental analyses. Mass distribution as well as physical and chemical characteristics among the isolated size fractions were strongly influenced by the dispersion level, indicating the importance to find optimal dispersion level. Upon minimum dispersion (wet sieving), over 95% of total C was present as >53μm aggregates and the C concentration and C:N ratio remained constant across all size fractions. Even after mechanical shaking, >53μm and 2–53μm fractions accounted for 37% and 41% of total C, respectively. Maximum dispersion was achieved only after sodium saturation pretreatment followed by the sonication at the energy level 5–10 folds higher than normally required for non-volcanic soils (5kJmL−1). While dissolving minor levels of organic matter and metals, the maximum dispersion treatment liberated large amounts of small particles (<2μm) that were enriched in N-rich organic matter, SRO mineral, and organo-metallic complex and that accounted for 48% of total mass, 63% of C, N, and 72 to 91% of extractable phases of Al, Si, and Fe by pyrophosphate and acid-oxalate. The step-wise breakdown of macro- and micro-aggregates with concurrent liberation of micron- to submicron-size particles upon the increased levels of dispersion, therefore, represents clear evidence of aggregate hierarchy on this soil type. Due to their abundance and chemistry, the small particles (<0.2 and 0.2–2.0μm fractions) likely acted as strong binding agents to form both micro- and macro-aggregates. Significant positive correlation of organic matter concentration and C:N ratio against the extractable metal concentrations was found when samples of all size fractions and dispersion treatments were combined. We proposed a simple conceptual model for Andisol aggregate hierarchy to explain the observed variation in the abundance and chemistry of isolated fractions.

Free and intra‐aggregate organic matter as indicators of soil quality change in volcanic soils under contrasting crop rotations

AbstractSoil physical fractionation techniques may provide indicators of changing soil organic carbon (SOC) content; however, they have not been widely tested on volcanic soils (Andisols). In this study, we assessed two fractions as potential indicators in volcanic soils, using two sites in Chile converted from natural grassland to arable and mixed crop rotations, 8 and 16 yr previously. In the 8‐yr experiment, SOC had declined under all rotations, with smaller changes where the rotation included 3 or 5 yr of perennial pasture. Whereas the average SOC was only 76% of the level in the preceding natural grassland, the corresponding value after 16 yr for the second site was 98% (and 93% under continuous arable), probably reflecting its high allophane clay content. The fractionation procedure tested proved applicable to both Andisols, but the intra‐aggregate light fraction (IA‐SOM, isolated in sodium iodide solution at 1.80 g/cm3 after ultrasonic dispersion) accounted for a very small proportion of total SOC (&lt;1%). We suggest that in Andisols, the free light fraction (FR‐SOM, isolated in sodium iodide at solution of the same density, but prior to ultrasonic dispersion) is stabilised to a greater extent than in nonvolcanic soils, and the intra‐aggregate fraction plays a more minor role as a pool of intermediate turnover. The relative value of each fraction needs to be confirmed through dynamic experiments, using more sites, and including situations where SOC content is initially low.

Geochemical Distributions of Heavy Metals and Cr Behavior in Natural and Cultivated Soils of Volcanic Jeju Island, Korea

ABSTRACTVolcanic ash soils, representative soil series (Andisols) on Jeju Island, Korea were collected to investigate the geochemical and mineralogical characteristics. Distributions of heavy metals and Cr behavior, in particular, were further assessed according to land uses (natural or cultivated). The natural soil samples had ferromagnesian minerals mostly in mineralogy, high levels of organic matter, silty textures, and acidic pH. Low amounts of SiO2 and high contents of Al2O3 and Fe2O3, were found in the Jeju soils, which are typical characteristics of Andisols compared to other soil orders. The mean total concentrations of Zn (127 mg/kg), Ni (183 mg/kg), Co (84 mg/kg), and Cr (677 mg/kg) were higher than worldwide values in most of the natural soils. Especially, Cr was a main soil contaminant, exceeding 1000 mg/kg in some soil series. The relationships between heavy metals and major elements indicated a ferromagnesian mineral origin for heavy metals and secondary associations with Fe and Al oxides during weathering processes. Cultivated soils also had similar volcanic ash soil properties, but showed more clayey textures, greater SiO2, and lower Al2O3 and Fe2O3 contents compared to natural soils. The average heavy metal content was not affected by cultivation, and characteristic behavior was maintained, except for slight increases in Cu, Pb, and Zn contents in surface soils because of fertilizer inputs. The only distinct decrease was in Cr content in the surface and subsurface of cultivated soils. This decrease might reflect the formation of a soluble organic complex of Cr(III), based on the significant increase in the sodium pyrophosphate-extracted fraction in sequential extractions. However, the high reducing capacities of volcanic ash soils compared to inland non-volcanic soils suggest that the potential for contamination by Cr(VI) can be significantly very low.

Soil methane oxidation and methanotroph responses to afforestation of pastures with Pinus radiata stands

Afforestation of pastures in New Zealand reduces methane (CH 4) production from soil, while also stimulating oxidation of atmospheric CH 4 by soil methanotrophs. However, neither the mechanisms by which soil CH 4 oxidation is enhanced by afforestation, nor how long after forest planting tree-dependent responses in CH 4 oxidation become detectable are fully known. Here, we investigated the effects of different-aged stands (5–20 y) of the exotic pine ( Pinus radiata (D. Don)) on CH 4 oxidation and methanotrophic community structure in soils, compared with adjacent, long-established pastures. Two of the pastures were on volcanic soils and two were on non-volcanic soils. Although the CH 4 fluxes in soils from these young stands were not significantly different from those in the associated pastures, the rate of oxidation of added 13CH 4 was higher in the pine soils. Both fluxes and 13CH 4 oxidation rates were higher in the volcanic than the non-volcanic soils. Combined phospholipid fatty acid (PLFA) and stable isotope probe (SIP) analyses suggested that type II methanotrophs (PLFA C18:1ω7) were most active in all soils followed by uncultivable bacteria (C17:0ai). Molecular analysis of the methanotrophic community structure using pmoA (particulate methane monooxygenase) genes suggested that a particular type II methanotroph (TRF 35) was dominant in all soils, but more so in the pine than in pasture soils. A type I methanotroph (TRF 245) was more prevalent in the pasture than in associated pine soils, whereas TRF 128 (a type II methanotroph) was slightly more dominant in soils under pine. Cloning and sequencing data suggest TRFs 35 and 128, which differ from one another, belong to distant relatives of Methylocapsa sp; TRF 245 is related to Methylococcus capsulatus. Land-use change resulted in changes in soil bulk density, porosity, moisture contents and in methanotrophic community structure. Methane oxidation rates were most closely related to soil moisture, as well as to the methanotrophic community structure, and nitrate-N, extractable C and total C concentrations. Stepwise multiple regression also suggested a weak effect ( P = 0.06) of stand age on CH 4 oxidation rate. By contrast, the responses of the methanotrophic community structure to this land-use change were more readily detected by the specific molecular analyses, and indicated a predominance of type II methanotrophs in pine soils.

Abstracts of Nippon Dojo-Hiryogaku Zasshi

Abstracts of Nippon Dojo-Hiryogaku Zasshi