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Aim: Pheomelanin is a pigment responsible for yellowish‐to‐reddish colours of vertebrate teguments. Its biosynthesis is favoured under high concentration of intracellular thiols, which, in turn, can depend on the environmental exposure to sulphur. Thus, pheomelanin production should be more intense and frequent in environments characterized by high level of sulphur, such as volcanic regions. In this study, we aimed at addressing this hypothesis by investigating variation in plumage colour of insular populations of the cosmopolitan barn owl (Tyto alba species complex) according to the presence of soils of volcanic origin (i.e. andosols) and recent volcanic activity. Location: World. Taxon: Barn owl species complex. Methods: We measured plumage colouration of more than 2000 museum specimens from 50 islands and archipelagos worldwide. We then compared plumage colouration between populations living on volcanic (i.e. where andosols and/or recent volcanic activity are present) and non‐volcanic islands/archipelagos. Results: Consistently with the prediction, plumage colouration is significantly darker (i.e. pheomelanic) on islands/archipelagos where andosols and/or recent volcanic activity are present than absent, although this environmental factor explains a small fraction of plumage colour variability across islands (<10%). Similar results were obtained when specimens' sex and climatic predictors were included in the analyses. Main Conclusions: Because excessive intracellular levels of thiols can be toxic, pheomelanin synthesis may function as a mechanism keeping these compounds below the toxicity threshold and limiting their detrimental effects on physiology. Darker plumage may also be favoured because it promotes background matching against the dark environment typical of volcanic islands (dense vegetation cover and/or dark soil). Our results add to the little evidence that the environmental exposure of compounds that are involved in melanin biosynthesis can affect animal pigmentation and suggest that soil composition may be a factor that affects melanogenesis, possibly contributing to generate spatial variation in pheomelanin‐based traits in animals. [ABSTRACT FROM AUTHOR]

Assessment of phosphorus (P)-infiltrating croplands is essential for the preservation of the water environment. It has been pointed out that a huge discrepancy lies in the different evaluation methods of P adsorption, such as batch experiments and column experiments, which makes it difficult to demonstrate P mobility under flow conditions. The objective of this study was to evaluate the applicability of the convective-dispersion equation using the parameters of the Langmuir-type isotherm obtained from batch experiments with different reaction times: the adsorption capacity of soil (qmax) = 0.112 (g kg-1) for a Gray lowland soil with 24 h reaction time, qmax = 0.484 (g kg-1) for an Andosol (volcanic ash soil) with 24 h reaction time, and qmax = 1.17 (g kg-1) for an Andosol with 32 d reaction time, for describing P mobility in typical Japanese agricultural soils under fast flow conditions. The breakthrough curves of P infiltrating the soil columns demonstrate nonequilibrium P adsorption by the soil. The chemical nonequilibrium model, with a kinetic adsorption rate of α = 0.40 (Gray lowland soil) and 0.098 (Andosol), succeeded in describing the observations in the column experiments. Compared with Gray lowland soil, which is relatively rich in iron oxide, P mobility was largely affected by kinetic sorption in Andosol, which is relatively rich in allophane. It is suggested that the P adsorption capacity of soils should be evaluated reflecting the soil composition in order to simulate the P mobility under flow conditions. In particular, the slow adsorption (long-lasting adsorption) of P by the soil should be considered in the estimation of the P transport. [ABSTRACT FROM AUTHOR]

Soil erosion has been a persistent problem in high‐latitude regions and may worsen as climate change unfolds and encourages increased anthropogenic exploitation. We propose that soil moisture is likely to shape future erosion trends, as moisture stress reduces the capacity of vegetation cover to retard erosive processes. However, the spatial variability of soil moisture in high‐latitude soils—and the ways in which this variability drives the spatial distribution of erosion features—is poorly understood. We addressed this knowledge gap with a study of andosol erosion in southern Iceland. Our study used a combination of high‐resolution (<3 cm) remote sensing data (using normalised difference vegetation index (NDVI) and normalised difference red edge as metrics of plant vitality) and long‐term, in situ measurements of soil moisture to unpick the relationship between moisture stress, vegetation vitality and patchy soil erosion. Mean NDVI increased with distance from eroded areas, varying from ~0.6 in vegetated areas on the margins of erosion patches to ~0.8 in areas >10 m from eroded terrain. We found lower moisture availability close to existing erosion features: mean volumetric soil moisture content varied from 17% (proximal to erosion patch) to 36% (distal to erosion patch). We also found that variability in soil moisture decreased with distance from eroded areas: the coefficient of variation (CV) in soil moisture varied from 0.33 (proximal to erosion patch) to 0.13 (distal to erosion). Our findings indicate that the margins of erosion patches have a stressful soil environment due to exposure to the atmosphere. The vegetation in these locations grows less vigorously, and the exposed soil becomes more vulnerable to erosion, leading to erosion patch expansion and coalescence. If these conditions hold more generally, they may represent a feedback mechanism that facilitates the lateral propagation of soil erosion in high‐latitude regions. [ABSTRACT FROM AUTHOR]

The pH of manure pellet fertilizer can affect the nitrous oxide (N2O) emission from soil, although its effectiveness and the relative mechanisms are not well understood. This study aims to quantify the effect of cattle-manure-based pellet pH on N2O emissions from an Andosol field. The field experiment consisted of four treatments: chemical (mineral) fertilizer (CF), cattle-manure-based pellet fertilizer of pH 5.6 (OP), cattle-manure-based pellet fertilizer of pH 7.1 (NP), and cattle-manure-based pellet fertilizer of pH 10.1 (AP). Cumulative N2O emission over the 365 days in the OP and NP treatments was 59.4% and 49.3% lower than that in the AP treatment, respectively, but the cumulative N2O emissions were statistically significant only between the OP and AP treatments. Moreover, cumulative N2O emission in the pellet fertilizer treatments during the peak period after fertilization in the autumn and spring cropping seasons (total 70 days) increased with increasing pellet pH. In the pellet fertilizer treatments, soil nitrification potential, soil N2O production rate, and total denitrification rate of soil also clearly increased with the increase of pellet pH. Therefore, slightly acidic pellet pH (OP treatment) may have inhibited the microbial N2O production processes in comparison to the neutral pellet pH (NP treatment), but alkaline pellet pH (AP treatment) could have stimulated the microbial N2O production processes than the neutral pellet pH. These results suggested that increased N2O emission with an increase in pellet pH may be attributed to a change in the N2O production rate via nitrification and denitrification. [ABSTRACT FROM AUTHOR]

Continuous use of only nitrogen (N) and phosphorus (P) containing fertilizers is claimed to be the causes of other secondary and micronutrients depletion, resulting in low crop productivity in Ethiopia. In this study, on-farm trials were conducted to compare the effect of multi-nutrient blended fertilizer – also called Sulfur (S) zinc (Zn) boron (B) (NPSZnB: 17.7 N – 35.3P2O5 – 7.6S – 0.25B-2.2Zn) on the yield and yield components of bread wheat grown in Andosols in south western Ethiopia during 2017 and 2018 cropping seasons. Seven treatments involving five levels of sulfur-zinc-born-blend fertilizer (50, 100, 150, 200, 300 kg NPSZnB kg ha−1) were compared against a compound fertilizer (100 kgha−1 NPS) and the conventionally used 150 kg ha−1 di-ammonium phosphate (DAP). For all treatments, 100 kg ha−1 was applied. The seven treatments were replicated three times using farm fields as replicates and arranged in randomized complete block design (RCBD). Results revealed no significant yield advantages of applying micronutrient containing fertilizers compared to fertilizers without micronutrients. The marginal rate of return analysis showed that the application of 100 NPSZnB kg ha−1 was the most profitable. Season had a significant (p <.001) effect on bread wheat yield. ZnB blended fertilizer was advantageous when applied during good rainy seasons in Andosols of Ethiopian highlands. For good performances of ZnB blended fertilizers, taking into account, the soil moisture availability is advised for better productivity and profitability. [ABSTRACT FROM AUTHOR]

Context: Soil enzyme activities are key regulators of carbon and nutrient cycling in grazed pastures. Aims: We investigated the effect of biochar addition on the activity of seven enzymes involved in the carbon, nitrogen and phosphorus cycles in a Sil-andic Andosol and a Dystric Cambisol under permanent pastures. Methods: The study consisted of a one-year field-based mesocosm experiment involving four pastures under different nutrient and livestock practices: with and without effluent under dairy cow grazing on the Andosol, and with either nil or high phosphorus fertiliser input under sheep grazing on the Cambisol. Soil treatments were: (1) willow biochar added at 1% w/w; (2) lime added at the liming equivalence of biochar (positive control); (3) no amendments (negative control). Key results: Compared with the Cambisol, the Andosol had higher dehydrogenase, urease, alkaline and acid phosphatase and, especially, nitrate-reductase activities, aligning with its higher pH and fertility. In both soils, biochar addition increased the activity of all enzymes, except for acid phosphatase and peroxidase; lime addition increased peroxidase and nitrate-reductase activity. Conclusions: The increased enzyme activity was strongly positively correlated with soil biological activity following biochar addition. Biochar caused a 40–45% increase in cellulase activity, attributed to increased root biomass following biochar addition. The response in acid and alkaline phosphatase activity can be attributed to the impact of biochar and lime addition on soil pH. Implications: The results provide more insights in realising the potential benefits of biochar to the provision of ecosystem services for grazed pastures. Willow wood biochar applied at a rate of 10.9 Mg ha−1 increased the activity of five out of seven soil enzymes. The increase in enzymes involved in nutrient and carbon cycling was strongly and positively correlated with soil biological activity. The 40–45% increase in cellulase activity was linked to enhanced root biomass following biochar addition. [ABSTRACT FROM AUTHOR]

The silt pit is a method of soil management that functions to accommodate and absorb surface runoff. The research aimed to determine the silt pit effectiveness for erosion reduction and nutrient loss. The research is located at 576 above sea level (asl) in Sukamantri village, Taman Sari district, Bogor Regency. The experiment used a randomized block design with three replications and a slope group. The treatments were R0 (without silt pit); R1 (silt pit); R2 (silt pit + mulch); R3 (silt pit + mulch + biopore tube), R4 (silt pit + mulch + biopore tube + vertical crop tube). The highest runoff-decreasing occurred on R4 treatment, which pressed down 29.38% runoff. The highest value of erosion-decreasing occurred on R2 as 68.74% and followed by effectiveness in reducing the loss of 71% Organic C, 76% available P, and 67% total N. The dry seeds peanut yield was around 0.54 - 0.86 Mg ha-1, dried pods was 0.96 - 1.33 Mg ha-1, and dried biomass was 5.16 - 6.23 Mg ha-1 and not significantly different between all treatments. This study recommends that farmers apply silt pit innovation technology with a combination of mulch, biopore, and mature green media because the incremental B/C ratio was 1.175. It is a good economic indicator for farmers.

Soil hydraulic properties control the provision of hydrological services. Vegetation and topography influence these properties by altering soil structure and porosity. The underlying mechanisms are not yet fully understood for the high Andean region. In this study, we examined how vegetation and topographic attributes are related to soil hydraulic properties and soil pore structure in young volcanic ash soils, and further correlated them to soil texture, organic carbon, and root characteristics to explain these relationships. In a 0.7 km2 study site located in the Andean páramo of northern Ecuador, we measured soil water retention, saturated hydraulic conductivity, bulk density (BD), and pore size distribution parameters on eight soil profiles with contrasting vegetation types (cushion‐forming plants vs. tussock grasses) and topographic positions (summit vs. hillslope). We observed significant differences in soil hydraulic properties and soil pore structure in the uppermost horizons by vegetation type, whereas topography had a minor effect. In the A horizons, we found higher water retention at saturation and field capacity (10%–14%), higher total available water (8%–15%), and higher saturated hydraulic conductivity (4–12 times) under cushion‐forming plants compared to tussock grasses. The elevated values under cushion plants were attributed to the presence of larger pores, lower soil BD, and higher soil organic carbon content as a result of coarser root systems. Total available water was generally high (0.34–0.40 cm3 cm−3), and locally not associated with any soil property. The higher water retention in soils under cushion vegetation can enhance soil water storage for plants and the regulation of water flows during prolonged rainfall events. The saturated hydraulic conductivity of the surface horizons is high compared to rainfall intensities resulting in high infiltration capacity; whilst its decline with depth reveals the potential for generation of subsurface stormflow, especially below cushion‐forming plants. Our findings highlight that soil hydraulic properties differ among vegetation types, and show the significance of vegetation types for soil hydrology. [ABSTRACT FROM AUTHOR]

The sowing-to-harvest period for the medicinal plant Ginseng (Panax ginseng Meyer) is 4–6 years. Although one of the primary soils used to cultivate ginseng in Japan is Andosol, there have been few studies of the changes in the soil's chemical properties during the cultivation of ginseng in Andosol soil. Here, we investigated the chemical properties of Andosol soil by collecting soil samples from cultivation sites with various numbers of years of ginseng cultivation. A significant negative correlation was observed between the years of cultivation and the soil's pH, indicating that soil acidification increased with an increasing number of years of cultivation. Similarly, exchangeable calcium (Ca) showed a significant negative correlation with the years of cultivation. The soluble aluminum (Al) concentration showed a significant positive correlation with the years of cultivation and was significantly negatively correlated with the exchangeable Ca and magnesium (Mg) contents. These results suggest that a decrease in pH due to Ca absorption by ginseng, increasing Al dissolution, and a further accelerated decrease in pH occur during the cultivation of ginseng in Andosols. The increase in soluble Al with increasing years of cultivation also affected the dynamics of essential trace elements in the soil, showing significant negative correlations with the soil's soluble copper (Cu) and zinc (Zn) contents, indicating that the Cu and Zn contents decreased with increasing Al. Our findings indicate that in the cultivation of ginseng on Andosol soil, the soil's soluble Al content is an essential factor in changes in the soil's chemical properties. [ABSTRACT FROM AUTHOR]

Precise estimation of sodium dodecylbenzenesulfonate (DBS) is essential for understanding its adsorption in soils, transport, toxicity, fate, and its application in the remediation of contaminated soil and groundwater. DBS can be easily identified by its conjugated double bond systems of benzene rings under the ultraviolet (UV) spectrum of a spectrophotometer. However, benzene group components of dissolved organic matter (DOM) also absorb light in the UV spectrum, and this effect is responsible for the excess quantities of DBS that are falsely measured by spectrophotometers. This study was conducted to propose a method for accurately measuring the DBS concentration of a solution containing DOM. To elucidate the influence of DOM during the UV‐spectroscopic measurement of DBS in an aqueous solution, 222.5 nm UV and 400 nm UV–vis spectra were measured. The DOM was extracted from a highly humic non‐allophanic volcanic ash (Andosol) soil by using 1 mmol NaCl/L and 100 mmol NaCl/L solutions as the extractants. The absorbances at both 222.5 and 400 nm increased in proportion to the increase in the DOM concentration. The relationship between the absorbances at the two different wavelengths could be expressed as a linear relationship. On the other hand, the absorbance at 400 nm did not increase with the increase in the DBS concentration, whereas the absorbance at 222.5 nm increased with the increase in the DOM concentration. Therefore, we inferred that the influence of DOM on the absorbance value of the DBS–DOM complex solution at 222.5 nm could be eliminated by using the linear relationship between the two different absorbances of the DBS‐free DOM solution. This method makes it possible to easily measure the DBS concentration of a solution from soil water, streams or industrial effluents containing DOM, without using reagents. Highlights: Dodecylbenzenesulfonate in a solution is overestimated in the presence of dissolved organic matter.Dodecylbenzenesulfonate becomes precisely detectable using 222.5 and 400 nm spectrophotometry.Our proposed method is simple, rapid, efficient, and requires no special reagent or recurring cost.This method can be used for precise DBS estimation in soil water, streams, or industrial effluents. [ABSTRACT FROM AUTHOR]

The application of organic fertilizers (OF) can supply carbon (C) to the soil in crop fields. OF-derived C (OF-C) is often estimated using the differential method that can be biased due to indirect effects of OF on soil C. This study tested three methods to quantify OF–C: (i) the widespread differential method, (ii) the synchronic isotope method comparing plots with and without OF and (iii) the asynchronic isotope method mimicking a trial without a control plot. These methods were implemented on an Arenosol and an Andosol supplied during 13 years with slurry or compost. The results highlighted the relevance of using the synchronic isotope method, which focuses on the direct effect of OFs on the soil organic matter (without bias of vegetation change) and considers control soil's evolution. The higher the isotopic difference between soil and OF, the shorter the method implementation time needed: for an initial difference of 7.5 ‰ and 3.5 ‰, quantification is suitable after 4 and 9 years of fertilization respectively. Attention should be paid to OF-δ13C variability to guarantee the method validity. The method proved to be suitable to study the factors controlling the OF-C fate in tropical soils. [ABSTRACT FROM AUTHOR]

It has been demonstrated that inoculation of Welsh onions (Allium fistulosum) with arbuscular mycorrhizal (AM) fungi during the nursery period followed by transplantation was effective in improving growth and reducing phosphorus fertilizer application. However, what range of soil phosphorus fertility is suitable for AM fungal inoculation remains unclear. To elucidate the optimal level of soil phosphorus fertility in a non-allophanic Andosol, we conducted a series of Welsh onion inoculation experiments under field conditions. Experiments were conducted in 2009–2010 and 2015–2016 in experimental plots at Tohoku University, northern Japan. Soil phosphorus fertility levels varied as follows: very high, high, medium, and low at 750–1,000, 150–250, 70–150, and 30–70 mg P2O5 kg soil−1, respectively (Truog method). Welsh onions were inoculated with a commercial Rhizophagus sp. R10 inoculum and grown for 7–9 weeks in a greenhouse nursery bed. The seedlings were transplanted into plots under the application of one, two or three levels of phosphorus fertilization. In the medium and high plots, inoculation increased marketable yields of Welsh onions irrespective of phosphorus fertilization, while no effect was found in the very high plot. In the low plot, inoculation did not clearly improve the yield, which was low irrespective of the treatments. These results indicate that AM fungal inoculation of Welsh onions in this soil was effective when available phosphorus ranged from 70 to 200 mg P2O5 kg soil−1. [ABSTRACT FROM AUTHOR]

To examine the hypothesis that the soil microbial community in a nitrogen (N) limited forest responds to moderately elevated N deposition (< 10 kg ha−1 yr−1), correlations between N deposition and soil microbial properties were analyzed in a cool temperate forest surrounded by normally fertilized pasture grasslands in northern Japan. Three experimental plots were established in forest edges adjacent to the grasslands, and the other three plots were in forest interiors at least 700 m away from the grasslands. N deposition in each plot was measured from May to November 2018. In August 2018, we collected litter and surface soil samples from all plots to measure net N mineralization and nitrification rates as indicators of microbial activity, and microbial biomass and various gene abundances (i.e., bacterial 16S rRNA gene, fungal ITS region, and bacterial and archaeal amoA genes) as indicators of microbial abundance. N deposition in forest edges was 1.4-fold greater than that in forest interiors, whereas maximum N deposition was 3.7 kg ha−1. N deposition was significantly correlated with net N mineralization and nitrification rates and 16S rRNA and bacterial amoA gene abundances. Microbial community structures analyzed for bacterial 16S rRNA gene and fungal ITS region amplicons were different between litter and soil samples but were similar between the forest edge and interior, although this analysis was made only for single pair of the two plots in the forest edge and interior. N deposition was also correlated with the soil C/N ratio and nitrate and ammonium contents. Thus, it was suggested that some soil microbial activities and abundances in an N limited forest likely responded to moderately elevated N deposition. These findings provide primary information on soil microbial response to moderately elevated N deposition. [ABSTRACT FROM AUTHOR]

The sowing-to-harvest period for the medicinal plant Ginseng (Panax ginseng Meyer) is 4–6 years. Although one of the primary soils used to cultivate ginseng in Japan is Andosol, there have been few studies of the changes in the soil’s chemical properties during the cultivation of ginseng in Andosol soil. Here, we investigated the chemical properties of Andosol soil by collecting soil samples from cultivation sites with various numbers of years of ginseng cultivation. A significant negative correlation was observed between the years of cultivation and the soil’s pH, indicating that soil acidification increased with an increasing number of years of cultivation. Similarly, exchangeable calcium (Ca) showed a significant negative correlation with the years of cultivation. The soluble aluminum (Al) concentration showed a significant positive correlation with the years of cultivation and was significantly negatively correlated with the exchangeable Ca and magnesium (Mg) contents. These results suggest that a decrease in pH due to Ca absorption by ginseng, increasing Al dissolution, and a further accelerated decrease in pH occur during the cultivation of ginseng in Andosols. The increase in soluble Al with increasing years of cultivation also affected the dynamics of essential trace elements in the soil, showing significant negative correlations with the soil’s soluble copper (Cu) and zinc (Zn) contents, indicating that the Cu and Zn contents decreased with increasing Al. Our findings indicate that in the cultivation of ginseng on Andosol soil, the soil’s soluble Al content is an essential factor in changes in the soil’s chemical properties.

The allophane is a natural nanoparticle present in soils from volcanic origin such as andisols, which are distributed worldwide, especially in countries that have active volcanoes. In Ecuador, andisols are in high and humid areas from the Highland/North region, constituting 30% of the territory. The allophane can be obtained from andisols through physical and chemical processes or it can be also synthesized. This nanomaterial has multiple properties for various applications in different areas; and there are studies about these nanoparticles and this kind of soil, but they have not yet been conducted in Ecuador. This article presents a review of structural characteristics, properties, formation, isolation, synthesis and uses of allophane to extend knowledge and encourage the conduction of research in these soils, which are the source of the aforementioned nanoparticle. The literature review was performed on Science Direct and Google Scholar databases using high impact articles related to natural or synthetic allophane. Allophane has characteristics that allow it to be used as an environmental remediator, bactericidal, anti-inflammatory, flame retardant, enzyme support and also in catalysis, photocatalysis and electrocatalysis. Considering the availability and the large area covered by andisols in Ecuador, research based on international investigations can be perform to take advantage of it. [ABSTRACT FROM AUTHOR]

The oxalate-extractable Al (Alo) of weathered Nantai-Imaichi (Nt-IK) tephra sampled at Kiwadajima in Tochigi Prefecture, Japan is more than twice as high as that of weathered Nantai-Shichihonzakura (Nt-SK) tephra. This difference is peculiar because the Nt-IK horizon is directly under the Nt-SK tephra, without a buried A horizon in between, and the Nt-IK compares with the Nt-SK in age. The scanning electron microscopic image of the polished section of the pumice prepared from the Nt-SK tephra indicated the presence of weathered product, which would be allophanic altermorph of the thin bubble-wall glass as determined by energy-dispersive X-ray analyses. The unweathered thick bubble-wall glass was also present in the Nt-SK pumice typically accompanied with the weathered product as a thin film on the periphery. In contrast, the Nt-IK tephra lacks unweathered glass, with almost all glass converted to allophanic materials. One of the reasons for the high Alo value of the Nt-IK tephra compared with the Nt-SK is that the former has almost no unweathered glass whereas the latter has them inside the thick bubble-wall glasses. [ABSTRACT FROM AUTHOR]

Paddy fields are generally submerged during the growing season and drained in the fallow season, and occasionally stimulating the air-drying effect and drying-rewetting effect on soil nitrogen (N) mineralization and soil carbon (C) decomposition. It is important to understand how these two effects take place in Andosol field under organic farming. To elucidate these effects, we incubated fresh, air-dried, and dried-rewetted paddy soil anaerobically under flooded condition. Soils were from the fields subjected to organic rice farming (ORF) for 4–5 years (4ORF), 8–9 years (8ORF), and 12 years (12ORF) with only rice residues and fallow weeds as organic matter applied, and cnventional rice farming (CRF). Soil samples were collected from plow layer of 0–15 cm depth after the rice harvest. The results showed that air-dried and dried-rewetted treatments could significantly increase N mineralization potential in 8ORF and 12ORF. The air-drying effects were not significantly changed in 4ORF, but significantly increased in 8ORF and 12ORF as compared to CRF. The drying-rewetting effects of C decomposition potentials were highest in 12ORF significantly. The N mineralization potential of air-drying effect showed no significant difference compared to drying-rewetting effect on conventional and organic rice farming. The ratio of C decomposition to N mineralization after 8 weeks incubation was higher in fresh soil (at 7.26–8.61) than those in air-dried (at 4.09–4.35) and dried-rewetted (at 3.94–4.26) soils. These indicated that the easily decomposable soil organic matter under the anaerobic flooded condition from fresh soil was changed by air-drying and drying-rewetting treatments. The slow increase of N mineralization and C decomposition with years of organic farming suggest the slow increase of fallow weed, the biomass of which gradually increase with years. The specific behavior of 12ORF soil suggest the transition of soil condition from a transitional state to an established state. [ABSTRACT FROM AUTHOR]

This work focused on the amounts and distribution of organic C (OC), organic phosphorus (Po), and acid phosphomonoesterase (AcP) and β-glucosidase (βG) activities in volcanic soils, as well as on the effect of inorganic P (Pi) on potential P-acquiring effort. The OC and Po contents are correlated with the active aluminum (Alox) and iron (Feox) and with the stratified gradients of the enzyme activities. The AcP activity does not seem to be suppressed by soil Pi content, showing a positive linear relationship with Pi. High values for the AcP:βG activity ratio are observed, which suggests a high energy allocation (C consumption) to ensure P demand. With the increase of Alox and Feox, the AcP:βG ratios increase and the potential C:P acquisition (ln(βG):ln(AcP)) values decrease. Nevertheless, the average C:P molar ratio of the six soils (115) are below the critical value, above which soils may present low P bioavailability. The results suggest that the effort for P acquisition (AcP:βG) and the potential C:P acquisition are both affected by the size of the Pi pools and by Alox and Feox contents. If Pi retention increases due to high contents of Alox and Feox, energy allocation shifts toward AcP production, in detriment of microbial population and plant nutrition. Considering the OC accumulation in the studied soils, several hypotheses may be considered such as the energy demand toward P acquisition, and the ability of Alox and Feox metal complexes to protect organic molecules to depress βG activity. [ABSTRACT FROM AUTHOR]

La presente investigación tuvo por objetivos conocer el comportamiento de la capacidad de retención de humedad de un Andosol con presencia de diferentes usos de suelo: forestal y agrícola (aguacate convencional, aguacate orgánico y macadamia); determinar la capacidad de campo (CC), el punto de marchitez permanente (PMP) y el agua disponible (AD [CC-PMP]); y validar seis funciones de pedotransferencia para CC y PMP. La curva de retención de humedad (CRH) se aplicó por medio del método de la placa y membrana de presión a distintas tensiones: 33 (CC); 50, 150, 500, 1 000 y 1 500 ([PMP] KPa), mediante extractores de placa en muestras recolectadas a dos profundidades (0-20 y 20-40 cm). Los resultados demuestran que existen diferencias significativas entre usos de suelo y tensiones. La CC registró valores en un intervalo de 55.95 a 69.03 %, con un PMP entre 33.54 a 45.66 % en la profundidad 0 - 20 cm; y de 40.99 a 62.02 %, con 25.27 a 36.89 % de PMP a una profundidad de 20 - 40 cm. De acuerdo a los resultados, la FPT que presentó la mayor capacidad de predicción para la estimación del contenido de agua fue la de Rawls y Brakensiek. El cambio de uso del suelo de terrenos forestales a cultivos agrícolas modifica la capacidad de un Andosol para retener humedad.

Long-term phosphorus (P) fertilizer application can lead to an accumulation of uranium (U) in agricultural soil, potentially posing risks on the environment and human health. In this study, we found that such risks could be severe in two long-term grasslands (Andosol) in Iceland (Sámstaðir and Geitasandur) after about 50 years of P fertilization. At Sámstaðir, where P fertilizers were applied at an annual rate of 39.3 kg ha−1 year−1, the soil U concentration increased from 0.65 mg kg−1 in the unfertilized soil to 6.9 mg kg−1 in the fertilized surface soil (0–5 cm). At Geitasandur with P fertilization rate at 78.6 kg ha−1 year−1, the soil U concentration reached 15 mg kg−1. The average annual U accumulation rates were 130 and 310 µg kg−1 year−1, respectively. These values were larger, by up to a factor of ten, than any previously reported rates of fertilizer-derived U accumulation. However, the U concentration in one of the applied P fertilizers was 95 mg U kg−1 fertilizer, similar to the median value of those reported in previous studies, and thus unlikely to be the only factor leading to the high U accumulation rates. By contrast, as our Andosols had low bulk density within a range of 0.2 to 0.5 g cm−3, the annual U inputs to the 0–5 cm soil were 19 g ha−1 year−1 and 32 g ha−1 year−1 at the two sites, respectively, within the range of to-date reported values in agricultural systems. In addition, we found that U was mostly retained in the surface soil rather than mobilizing to deeper soil. This was likely due to the fact that the Andosols were rich in organic matter which promoted U retention. Therefore, the observed high U accumulation rates were a result of the combination of (i) the large amounts of the applied P fertilizers and (ii) the soil properties of the Andosols with low bulk density and elevated organic matter content concentrating U in the upper surface soil. Our study shows that agricultural production systems on Andosols may have already suffered from severe U contamination due to P fertilization. We are therefore calling for future checks and regulations on P fertilizer-related soil U accumulation in these and certain comparable agroecosystems. [ABSTRACT FROM AUTHOR]

Currently, the cultivation of citronella grass (Cymbopogon nardus L.) is widely developed in highland areas dominated by Andosol soil. Andosol possesses low phosphorous availability, strongly bound to Al and Fe. This research was aimed to examine the effect of P fertilizer on C. nardus L. at Andosol. The research was conducted from June 2014 to August 2015. Phosphate fertilization stimulated plant growth, yield and oil quality of citronella grass on Andosol. The most suitable Phosphorus dosage at 1.08 g plant-1 (10.8 kg ha-1) produced high total fresh herb yield and oil quality of citronella grass. Total fresh herb yield increased 21.2% (3.4 kg plant-1 year-1) compared to control. Whereas citronella content, oil content and oil yield were 35.2%, 1.64% and 1.27% respectively. The phosphate residue in Andosol can be potentially utilized for the next planting season. [ABSTRACT FROM AUTHOR]

Fungi play an important role in the degradation of biodegradable plastics (BPs) in soil. However, little is known about their dynamics in the soil during the degradation of BPs. We studied the community dynamics of BP-degrading fungi during poly(butylene succinate-co-adipate) (PBSA) film degradation in two different types of soils using culture-dependent and culture-independent methods. The Fluvisol and the Andosol soils degrade embedded PBSA films at high and low speeds, respectively. The number of PBSA emulsion-degrading fungi that increased in the Fluvisol soil was higher than that in the Andosol soil after embedding with PBSA films. We succeeded in detecting internal transcribed spacer 1 (ITS1) regions those matched that of the fungi by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) in both soils. Our results suggest that fungal community analyses using PCR-DGGE in combination with BP degraders isolation techniques enables the monitoring of BP films-degrading fungi. Monitoring fungal population dynamics during the degradation of films comprising poly(butylene succinate-co-adipate) in a Fluvisol and an Andosol soil. [ABSTRACT FROM AUTHOR]

Strict regulations and permits in managing medical waste create dependency on third party. This has an impact on medical waste especially syringe medical waste which must be piled up waiting for the collection process. Improper handling medical waste may cause accidents and disease transmission. Soil has been known to be used as an antibacterial in medicine, but there is still little in the process of application in medical waste management. This study aims to determine the effectiveness of the use of autoclaves combined with andisol soils to decrease the number of bacterial colonies of Bacillus cereus. This study uses a true experiment design using a completely randomized design. The research was carried out starting from the isolation of bacteria from syringe medical waste and rejuvenation on sterile media to test the effect of the application treatment on a laboratory. Anova Repeated Measure Test (Ranova) at alpha 0.05 was used to determine differences in the number of bacteria that grew in the media before and after treatment. The results of this study indicate the combination treatment of autoclaves in the variation of contact time with andosol soils at variations in concentration produced the difference (p <0.001) with the number of bacterial colonies Bacillus cereus between 290,000-340,000 CFU / ml and the effectiveness of all treatments reaches 100%. At the end of this study, a combination of autoclave treatment at a temperature of 121 0C was taken for 15 minutes with andosol soil treatment at a concentration of 45% with a contact duration of 2 minutes that could be applied independently at the hospital. [ABSTRACT FROM AUTHOR]

• Effect of climate on pedogenesis on late Holocene tephra in a tropical mountain. • In ∼ 1100 years vitric andosols formed from 3000 to 4300 m a.s.l. on N- and S-facing slopes. • Allophane dominates on S-facing slopes, Al/Fe-humus complexes on N-facing slopes. The influence of climate on pedogenesis is elevation dependent, but little is known on the influence of slope orientation. This investigation focuses on the development of soils formed on Holocene (1100 and 5600 years old) volcanic ash deposits along an elevation gradient from 3000 to 4300 m a.s.l. on a high mountain in central Mexico. Soil profiles were analyzed on both N- and S-facing slopes at 3000, 3400, 3800, 4000 and 4300 m a.s.l. To determine the effect of climate (dependent on elevation and slope orientation) on pedogenetic processes, other factors such as age and type of parent material, landform position, and slope angle were kept constant. Soil temperature was recorded at 10 cm depth at each site for one year. Significant differences in temperature were found along the elevation gradient and between N-facing and S-facing slopes. Selective extractions of Fe, Al, and Si (using dithionite, oxalate, and pyrophosphate) indicate vitric properties on the 1100-year-old tephra (modern soil) throughout the elevation gradient, while the soil formed on the 5600-year-old tephra (buried by the 1100 year-old tephra) shows andic properties. The orientation of slopes has favored two evolutionary trajectories in the 1100-year-old soil: short-range-order minerals dominate on S-facing slopes, and organo-metallic complexes on N-facing slopes. The lower preservation of ash and pumice layers on S-facing slopes suggests that they have experienced geomorphic instability at centennial scales. The pedogenetic and stratigraphic differences observed between N- and S-facing slopes can be extrapolated to similar valleys and volcanic mountains. [ABSTRACT FROM AUTHOR]

To evaluate phosphorus (P) availability and the role of microorganisms in P dynamics in the barley rhizosphere, we constructed a rhizobox using two arable Andosols under different fertilization management regimens and cultivated barley (Hordeum vulgare L. cv. Minorimugi) for 5 weeks. The phosphatase-labile pool of organic phosphorus (Po) was assessed using a phosphatase-addition approach in combination with chemical extraction of Po from soils. A considerable amount of inorganic P (Pi) in the NaHCO3 fraction was taken up by barley roots in a soil with high Pi availability, whereas Po, primarily phytate-like P in the NaHCO3 fraction, was hydrolyzed and then taken up by barley roots in a soil with low Pi availability. No significant utilization of either NaOH-Pi or NaOH-Po was observed for both soils during the 5-week cultivation. In the soil with low Pi availability, elevated acid phosphomonoesterase and phosphodiesterase activities, and greater utilization of Po substrates by bacteria in the Biolog ECO plate, were observed in the rhizosphere when compared with those in the bulk soil. This suggested enhanced Po hydrolysis by increased phosphatase activities to meet the P demand, making the Po an important P source for barley in the soil.

Sorption of oxyanions by soils and mineral surfaces is of interest due to their role as nutrients or pollutants. Volcanic soils are variable charge soils, rich in active forms of aluminum and iron, and capable of sorbing anions. Sorption and desorption of vanadate, arsenate, and chromate by two African andosols was studied in laboratory experiments. Sorption isotherms were determined by equilibrating at 293 K soil samples with oxyanion solutions of concentrations between 0 and 100 mg L−1 V, As, or Cr, equivalent to 0−2.0 mmol V L−1, 0−1.3 mmol As L−1, and 0−1.9 mmol Cr L−1, in NaNO3; V, As, or Cr were determined by ICP-mass spectrometry in the equilibrium solution. After sorption, the soil samples were equilibrated with 0.02 M NaNO3 to study desorption. The isotherms were adjusted to mathematical models. After desorption with NaNO3, desorption experiments were carried out with a 1 mM phosphate. The sorption of vanadate and arsenate was greater than 90% of the amount added, while the chromate sorption was much lower (19–97%). The sorption by the Silandic Andosol is attributed to non-crystalline Fe and Al, while in the Vitric Andosol, crystalline iron species play a relevant role. The V and Cr sorption isotherms fitted to the Freundlich model, while the As sorption isotherms conformed to the Temkin model. For the highest concentrations of oxyanions in the equilibrating solution, the sorbed concentrations were 37–38 mmol V kg−1, 25 mmol As kg−1, and 7.2–8.8 mmol Cr kg−1. The desorption was low for V and As and high for Cr. The comparison of the sorption and desorption isotherms reveals a pronounced hysteresis for V in both andosols and for Cr in the Silandic Andosol. Phosphate induced almost no V desorption, moderate As desorption, and considerable Cr desorption.

Rice husk charcoal (RC) produced from the pyrolysis of rice husk (RH) can be one of the cost-effective biochars for use in rice-based farming systems. This study investigated changes in rice yield and soil carbon sequestration over three years of RC application to an Andosol paddy field. The treatments were RC application at 0.02, 0.2, and 2 kg m−2 (RC0.02, RC0.2, and RC2, respectively), RH application at 0.2 kg m−2 (RH0.2), and a control with no RC or RH application (CONT). The results showed that RC2 increased culm length by 4% and straw weight by 14% on average over the three years. These increases in plant growth coincided with a higher level of silicon uptake by the rice plants, although they did not significantly affect grain yield. The soil carbon content was progressively increased by RC2 over the three years, whereas it was not significantly affected by RC0.02 or RC0.2. A considerable amount (>72%) of the applied carbon with RC2 remained in the soil by taking account of its downward movement below the 10 cm layer of the paddy field after three consecutive years of RC application. We conclude that rice husk charcoal application to Andosol paddy fields is an effective option for increasing carbon sequestration. Furthermore, the increase in silicon uptake by rice plants suggests that rice husk charcoal can also be functioning as a silicon fertilizer.

• Microbial communities were investigated in natural and artificial forests. • Fungal and bacterial community structures differed among forest types. • Diversity indexes of microbes did not change with forest conversion. • Microbial co-occurrence networks of artificial forests were fragile. • Forest conversion affected the microbial co-occurrence network but not diversity. Tree species influence the chemical properties of the organic horizon and mineral soil. Microbial communities, including fungi and bacteria, which are the main drivers of nutrient cycles in forest soils, may be affected by tree species via litter chemical properties and root exudation. Therefore, conversion from natural forest to plantation could affect the microbial communities. Here, we aimed to reveal the effects of conversion from natural forest to coniferous plantation on soil microbial community structure, biodiversity, and co-occurrence networks, as well as soil chemical properties. For this purpose, we investigated chemical and microbial properties of the organic horizon and mineral topsoil (0–10 cm depth) in three forest types (a natural forest dominated by broad-leaved deciduous trees, and two types of plantations). Forest type had significant effects on chemical properties, including the C/N ratio, pH, and dissolved inorganic N of the organic horizon, while it had no significant effect on the chemical properties of topsoil, except for microbial biomass N and C. Microbial community structures in both the organic horizon and topsoil differed significantly among forest types and with changes in soil properties such as pH and C/N ratio. Microbial diversity indices did not significantly differ among forest types in either layer, while the microbial co-occurrence networks in the mineral soil of the natural forest were more complex and robust than the networks of plantations. Therefore, our results showed that conversion from natural forest to coniferous plantation could affect soil chemical properties and microbial community structure in the organic horizon, and the microbial co-occurrence network in the mineral topsoil; these impacts may vary according to the planted tree species. [ABSTRACT FROM AUTHOR]

The application of biochar can affect the nitrous oxide (N2O) emissions from soil. Although laboratory studies reported that biochar applications can reduce N2O emissions, the number of field-based studies is still limited. Therefore, in the present study, we investigated the effects of four different types of biochars and their interactions with a variety of environmental parameters on N2O emissions from an Andosol field over a 2-year period (2015–2016). The field experiment consisted of five treatments: chemical (mineral) fertilizer without biochar (CF), chemical fertilizer with rice husk biochar (RH), chemical fertilizer with chipped bamboo biochar (BA), chemical fertilizer with chipped hardwood biochar (HW), and chemical fertilizer with chipped wood briquette biochar made from a mixture of softwood and hardwood sawdust (SH). Biochar was applied at a rate of 25 t ha−1. The NH4+–N and NO3−–N adsorption capacity of biochars before application was also measured. NH4+–N adsorption capacity differed among the biochars, while biochars showed very little NO3−–N absorption capacity. The cumulative N2O emission of biochar treatment to that of the CF treatment during the N2O peak period (17 days) after biochar and fertilizer application increased with the increase of NH4+–N adsorption capacity of the biochar. However, biochar application did not affect the cumulative N2O emission over 2 years in the field condition. The lack of significant differences may have been due to Andosol CEC (31.3 cmol(+) kg−1), which was higher than that of the biochars (4.52–19.65 cmol(+) kg−1), and also high pH-buffering capacity of Andosol. [ABSTRACT FROM AUTHOR]

We compared the soil sorption coefficient (Kd) measured by batch and centrifugation methods using a Japanese andosol and ten pesticides. Although the Kd values measured by both methods increased with time, those obtained via the batch method tended to be higher during the test period. The difference in Kd values between the two methods affected pesticide concentrations estimated in the soil solution, and the results estimated using Kd values obtained via the batch method underestimated the observed trends. [ABSTRACT FROM AUTHOR]

This study discusses penetration resistance (PR) of forested Pumice-Andosol sites. PR, a key soil property influencing root growth and elongation, exerts a substantial influence on ecological site quality and tree growth. Andosols were expected to show low PR because of their unique characteristics (low bulk density, loose soil matrix). Five sites, two undisturbed and three backfilled, were sampled. The latter result from pumice excavation and were examined to quantify potential PR alterations in the aftermath of backfilling and pumice removal. Penetrologger sampling on undisturbed sites showed mean PR not exceeding 3 MPa, a literature-based, critical threshold restricting root growth, in the upper 0.80 m, indicating conditions fostering tree rooting. Backfilled sites mostly exhibited increased (> 3 MPa) PR, leading to rooting restrictions even beginning at −0.21 m. Deviations from undisturbed soils range from −15.6 to +109.3% depending on depth and age of the backfilled site. Furthermore, GIS-based data interpolation helped to identify spatial PR patterns and allowed a direct comparison before/after backfilling at one site. Statistical analysis revealed significantly altered PR after backfilling, while a concluding ANOVA provided at least significant governing factors (depth, area, clay + silt content, soil organic matter), albeit with only small effect sizes.

Dicyandiamide, a routinely used commercial nitrification inhibitor (NI), inhibits ammonia oxidation catalyzed by ammonia monooxygenase (AMO). Phenylhydrazine hydrochloride has shown considerable potential for the development of next-generation NIs targeting hydroxylamine dehydrogenase (HAO). The effects of the AMO inhibitor and the HAO inhibitor on ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) present in agricultural soils have not been compared thus far. In the present study, the effects of the two inhibitors on soil nitrification and the abundance of AOA and AOB as well as their community structure were investigated in a soil microcosm using quantitative polymerase chain reaction and pyrosequencing. The net nitrification rates and the growth of AOA and AOB in this soil microcosm were inhibited by both NIs. Both NIs had limited effect on the community structure of AOB and no effect on that of AOA in this soil microcosm. The effects of phenylhydrazine hydrochloride were similar to those of dicyandiamide. These results indicated that organohydrazine-based NIs have potential for the development of next-generation NIs targeting HAO in the future.