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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 (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.

Context Rock type may exert strong control on pedogenesis and resulting soil characteristics. Little is known on how different volcanic lithologies influence soil formation and nutrient supply and thereby affect ecosystem productivity in volcanic landscapes. Aims The aim of this study was to investigate lithologic control on the mentioned properties and processes. Methods We conducted a side-by-side comparison of two contrasting sites in close proximity on Alcedo Volcano, Galápagos, one on basaltic lava and the other on rhyolitic pumice. Key results The lava site was covered by lush, stratified woodland, whereas the pumice site was covered by grassland with only few plant species. The soil on lava was a Leptosol, whereas on pumice, an Andosol had formed. Both soils had similar pH (6.0–6.5 in H2O), but the soil organic carbon stocks at the lava site were almost twice as high as at the pumice site (13.1 ± 1.6 vs 7.6 ± 1.3 kg m−2 to 25 cm depth). The soil at the pumice site had considerably lower levels of Mehlich-3-extractable P, Ca, Mg, Cu, Zn and B. Soil microbes at the pumice site had lower biomass P (and a higher C:P ratio) and excreted more phosphatase. The grass biomass here also showed lower (and deficient) levels of P and other nutrients compared to the lava site. Conclusions and implications The contrasting lithologies and their bearings on soil formation and nutrient availability diversify the aboveground and belowground ecosystems and favour the development of distinct ecological niches in close proximity.

La infiltración es un indicador de la capacidad del suelo para retener o drenar el agua, se ve influenciada por la cubierta vegetal y tipo de suelo, que al ser alterada modifica sus atributos. El objetivo de la investigación fue evaluar el comportamiento de la infiltración en un Andosol. Se establecieron parcelas de 100 m2, en cuatro áreas bajo dos usos de suelo: un área forestal y tres agrícolas [dos parcelas de cultivo de aguacate (bajo manejo orgánico y convencional) y una parcela más de macadamia con manejo orgánico], el año de referencia de la investigación fue 2018. Se determinó la infiltración in situ por medio del método de doble anillo tomando lecturas por un período de 150 minutos con recargas variables. Se obtuvieron los parámetros de tres modelos empíricos para estimar la infiltración: Horton, Kostiakov y Mezencev. El uso forestal presentó la mayor infiltración inicial, final, básica y acumulada observadas con valores de 1 880, 863.47, 885.92 mm h-1 y 2 793.29 mm, mientras que la parcela de aguacate con manejo convencional mostro los valores más bajos con 620, 248.27, 254.83 mm h-1 y 872.49 mm, respectivamente. Los resultados del ajuste de modelos demostraron que el modelo de Kostiakov predice en mejor medida el proceso de infiltración, esto de acuerdo con los valores de NSE, r, MAE y R2. Los cambios de uso forestal a usos agrícolas provocan cambios en las variables hidrológicas del recurso suelo. La infiltración presentó mayores tasas de velocidad bajo manejos orgánicos que convencionales.

The self-sufficiency ratio and national average yield of wheat are low in Japan. Reducing the yield gap and receiving the government subsidy for grain quality are vital strategies for profitability. Elucidating optimum nitrogen application scheme is awaited to attain both higher yield and appropriate grain protein content (GPC) for wheat cultivation in Japan. Such decision support can be realized by integrating field experimental knowledge to crop growth models, although they have scarcely been utilized for wheat production in Japan. Therefore, the purposes of this study were to apply a widely used crop growth model (APSIM) to wheat growth on an Andosol in the Kanto region in Japan by calibration and validation. Selected model parameters of APSIM-wheat for phenology, leaf growth, and grain formation were readjusted based on the phenology and growth data of soft and hard wheat cultivars. Then the model was validated by using similar variables obtained in an independent experiment. For the simulation of the optimum sowing for winter wheat in the Kanto area (November), the root mean square error for grain yield was 23 and 48 g m−2 for Ayahikari and Yumeshiho varieties, respectively, and that for GPC was 1.9 and 1.4%. Thus, the overall model performance was acceptable for optimum sowing. However, grain yield and dry matter production were significantly overestimated when the data of late sowing groups were included. Therefore, further model improvement was suggested to add an algorithm to reduce the number of emerged plants under cold temperature in late sowing conditions.

There is concern about nitrification inhibitor (NI) residues in soil and pasture plants and their potential entry into food-chain when NIs are applied to pastures to mitigate nitrogen (N) losses. Monitoring of NI residues necessitates development of quantitative methods for their extraction and analysis in soil and pasture samples. Modifications were made to published methods for extraction of two commonly used NIs [3,4-dimethylpyrazole phosphate (DMPP), and 2-chloro-6-(trichloromethyl) pyridine (nitrapyrin)], from soil and pasture. Detection and measurement of DMPP and nitrapyrin was via HPLC–UV and GC–MS, respectively. The modifications removed matrix interferences in detection and/or improved extractability. The methods were tested using an Alisol (Manawatū) and an Andosol (Waikato) soil, and pasture from urine patches. The detection limits in soil and pasture samples were 0.01 and 0.05 mg kg–1 for DMPP and nitrapyrin, respectively. There was high linearity (R2 ≥ 0.998) observed between the amount of NI added and the amount recovered in soil or pasture samples with no influence of urine matrix in recovery. Overall, recovery of both NIs in pasture samples (DMPP – 89% and nitrapyrin – 115%) were higher than those in soils, DMPP being higher in Manawatu soil (65%) than in the Waikato soil (54%), and nitrapyrin higher in Waikato soil (81%) relative to Manawatu soil (71%). The methods proved reliable, precise, and reproducible for measuring DMPP and nitrapyrin in soil and pasture with or without presence of urine and will be suitable for data collection to establish and meet maximum residue levels.

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.

Greywater is household waste sourced from kitchens and bathrooms, except for toilets. Around 58%-85% of greywater can be generated from the total volume of household wastewater per house. It is necessary to treat wastewater before it is discharged into water bodies to prevent the adverse effects of contaminants on the environment and human health while reducing the demand for clean water. However, due to environmentally friendly, socially sustainable, and economical treatment costs, considering that greywater is produced every day and continuously, Multi Soil Layering (MSL) technology can be an alternative to remove contaminants in water. Thus, this study aims to determine the migration of COD in greywater using MSL technology. Other parameters tested were pH and temperature by taking samples of wastewater in residential areas of Semarang City. In this study, there are two stages, namely the preliminary stage and the running stage. The MSL system will use three reactors with andosol soil, apus bamboo, and coconut shell activated charcoal as mixed soil blocks (SMB). Reactor A (activated charcoal and andosol soil), reactor B (bamboo apus and andosol soil), reactor C (andosol soil, bamboo apus, activated charcoal). The results of domestic wastewater treatment using the MSL method in each of the three reactors could remove COD by 75%, 74%, and 76%. Reactor C obtained the highest COD removal efficiency compared to other reactors.

In the tropics, frequent nitrogen (N) fertilization of grazing areas can potentially increase nitrous oxide (N2O) emissions. The application of nitrification inhibitors has been reported as an effective management practice for potentially reducing N loss from the soil-plant system and improving N use efficiency (NUE). The aim of this study was to determine the effect of the co-application of nitrapyrin (a nitrification inhibitor, NI) and urea in a tropical Andosol on the behavior of N and the emissions of N2O from autotrophic and heterotrophic nitrification. A greenhouse experiment was performed using a soil (pH 5.9, organic matter content 78 g kg–1, and N 5.6 g kg–1) sown with Cynodon nlemfuensis at 60% water-filled pore space to quantify total N2O emissions, N2O derived from fertilizer, soil ammonium (NH4+) and nitrate (NO3–), and NUE. The study included treatments that received deionized water only (control, CK) and two doses of 15N-enriched urea (65 (UR) and 129 mg N kg–1 (UD)) without or with 350 g nitrapyrin for each 100 kg N (UR + NI and UD + NI). No significant differences were observed in soil NH+ content between the UR and UR + NI treatments, probably because of soil mineralization and immobilization (influenced by high soil organic matter content). Nitrapyrin application failed to maintain a stable pool of labeled NO3− due to the additional NO− produced by heterotrophic nitrification, which is not effectively inhibited by nitrapyrin. After 56 d, N2O emissions in UR (0.51 ± 0.12 mg N2O-N kg–1) and UR + NI (0.45 ± 0.13 mg N2O-N kg–1) were not significantly different; by contrast, emissions were 36.3% lower in UD + NI than in UD. It was concluded that the soil organic N mineralization and heterotrophic nitrification are the main processes of NH4+ and NO3– production. Additionally, it was found that N2O emissions were partially a consequence of the direct oxidation of the soil's organic N via heterotrophic nitrification coupled to denitrification. Finally, the results suggest that nitrapyrin would likely exert significant mitigation on N2O emissions only if a substantial N surplus exists in soils with high organic matter content. Universidad de Costa Rica/[802-B7-505]/UCR/Costa Rica Organismo Internacional de Energía Atómica/[No. CRP DI.50.16]/IAEA/Estados Unidos UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro en Investigación en Contaminación Ambiental (CICA)

To clarify the effects of long-term fertilization on the depth profile of plant nutrients and soil acidity in non-allophanic Andosols, a soil survey was conducted on fertilized grassland and adjace...

Se analizaron las principales características químicas para determinar el estado de fertilidad de los suelos tipo Andosol, Vertisol y Gleysol, donde se establece el sistema productivo caña de azúcar en Zapoapan de Amapan perteneciente al municipio de Hueyapan de Ocampo del estado de Veracruz. La importancia de este trabajo radica en ubicar la situación que origina rendimientos muy por debajo de lo que se específica para México. El objetivo del presente trabajo fue evaluar los parámetros pH, materia orgánica, conductividad eléctrica, nitrógeno inorgánico, fósforo, contenidos de potasio, calcio, magnesio, fierro, cobre, manganeso, boro y densidad aparente, siguiendo los métodos establecidos en la NOM-021-RECNAT-2000, para ubicar el estado de fertilidad de los suelos y los posibles impactos ambientales ejercidos sobre este recurso natural. Los resultados mostraron que los suelos andosoles tuvieron las mejores condiciones de fertilidad para el cultivo de caña de azúcar; en tanto que los suelos tipo vertisol mostraron problemas leves de contaminación por los contenidos de boro obtenidos. La materia orgánica y el nitrógeno inorgánico son las variables que se deben atender para mejorar la fertilidad de los suelos. La producción de caña de azúcar en la comunidad de Zapoapan de Amapan, es baja (de 25 a 50 ton hectárea), por lo que se recomienda mejorar las prácticas agrícolas con el fin de incrementar los contenidos de nutrimentos en los tres tipos de suelo.

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.

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...

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 t...

Very few studies to date have focused on phosphorus (P) dynamics and microbial P acquisition during anaerobic soil disinfestation (ASD), an alternative to chemical soil fumigation for soil diseases. We evaluated the effects of ASD using diluted ethanol as well as the effects of drying treatments following ASD on available P concentrations, phosphomonoesterase activity, microbial biomass P, and microbial community compositions, including those harboring the alkaline phosphomonoesterase gene (phoD), in two arable Andosols. An increase in the Bray-2P concentration and a decrease in the ratio of phosphomonoesterase/β-D-glucosidase activities were observed during ASD in both soils, indicating an increase in P availability during ASD. A significant negative correlation between the diversity of profile of denaturing gradient gel electrophoresis for phoD-harboring community and alkaline phosphomonoesterase activity was found, suggesting that a less diverse bacterial group might produce alkaline phosphomonoesterase in soils with higher activity. ASD followed by drying and rewetting significantly increased the Bray-2P concentration and microbial biomass P in one Andosol. These results support the potential of ASD to increase P availability in addition to suppressing soil-borne diseases in arable Andosols.

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.

Introduction: World agriculture is characterized by intensive land use, which causes variations in physical and hydrological properties, regarded as key for agricultural productivity. Objective: To study the effect of land use change from forest to agriculture land with organic and conventional management on the physical and hydrological properties of an Andosol. Materials and methods: Four land use scenarios were evaluated: a forest land use scenario, two with Persea americana Mill var. Hass with conventional and organic management, and one with Macadamia integrifolia Maiden & Betche. Physical properties (texture, bulk density [BD], mechanical resistance to penetration [MRP] and porosity) and hydrological properties (moisture, hydraulic conductivity, infiltration, permanent wilting point [PWP], field capacity and available water) were determined. These variables were analyzed by parametric (ANOVA) and non-parametric (Kruskal-Wallis) statistics to determine differences among land use scenarios and depths (0 to 20 cm and 20 to 40 cm). Results and discussion: The ANOVA showed significant differences (P ≤ 0.05) in physical and hydrological properties among land use scenarios; infiltrations decreased 40 to 70 % in agricultural systems with respect to forest use. For the depth factor, no differences were observed in the case of hydrological variables only in PWP and silt. Interaction was only significant for BD. Porosity, MRP, BD and clay defined the behavior of the hydrological variables. Conclusions: The change from forest to agricultural land use causes significant variations in the physical and hydrological properties of an Andosol soil. The infiltration process was the most affected.

We investigated the effects of tillage on growth, grain yield and root lodging of maize hybrids in upland fields converted from paddy fields in Andosol of northern Tohoku. Six hybrids were grown with rotary tilling or plowing (chisel plowing plus power harrow) in 2016 and 2017. Soil penetration resistance was higher in plowing than in rotary tilling under a soil depth of 5 cm. There were no significant interactions between hybrid and tillage method in plant height, SPAD value, grain yield, and yield components, indicating that growth and grain yield of the six hybrids were unaffected by tillage method. Maize hybrids had similar culm length and ear height, while horizontal pulling resistance was higher in plowing than in rotary tilling. In addition, root lodged plants caused by typhoons were fewer in plowing than in rotary tilling in 2017. There was a negative correlation between horizontal pulling resistance and the number of root lodged plants. The highest horizontal pulling resistance and the least number of root lodged plants were found in a maize hybrid KD641 grown by plowing. The results suggest that root lodging can be alleviated by growing root-lodging-resistant maize hybrids such as KD641 with plowing.

High concentration (more than 1.0 mgP/L) of phosphorus was detected in groundwater in Aso caldera, Kumamoto. The fact indicates phosphorus can be transported by groundwater flows. The objective of this study is to clarify the characteristics of paddy soil (Andosol) in phosphorus adsorption process. Adsorption capacity of the Andosol was evaluated by continuously-flowing system using the soil column. In addition, soil phosphorus was categorized into five fractions; water-extractable phosphorus (Water-P), phosphorus extracted by sodium bicarbonate and sodium dithionate (DB-P), phosphorus extracted by sodium hydroxide (NaOH-P), phosphorus extracted by hydrochloric acid (HCl-P) and residual phosphorus (Res-P). As a result, it is confirmed that the flow rate of water is an important factor to control the phosphorus adsorption by the Andosol. The lower the flow rate is, the more phosphorus is adsorbed on the upstream soil. On the other hand, when the flow rate was high, phosphorus was evenly distributed in column soil. In addition, the fraction of NaOH-P accounted for 52% of the adsorbed phosphorus, suggesting that NaOH-P is the most important fraction which controls phosphorus adsorption to Andosol.

International audience; Chlordecone (CLD), used to control the Cosmopolites sordidus banana weevil and released from polluted banana plantations, continues to contaminate ecosystems in the French Caribbean. Edible plants have been actively studied for risk prevention, but trees have not, even though they could play a significant role in future remediation strategies. CLD contents were analysed in 24 pioneer trees belonging to 13 species found in abandoned banana plantations inGuadeloupe, at three contaminated sites on Nitisols (Site 1) and Andosols (Sites 2 and 3). Samples were taken from each tree: wood in the basal part of the trunk and soil at its foot and their CLD content was measured by the analytical laboratory for the Drôme département (26) in Valence, France. Mean CLD contents in the top 30-centimetre soil layer from sites 1, 2 and 3 were 2,543 ± 702, 5,251 ± 1,102 and 875 ± 865 μg/kg dry soil respectively. Of the trees, 96% werecontaminated. The CLD content in trees growing on Nitisols (3,406 ± 1,658 μg/kg dry wood) was at least 5 times higher than in trees growing on Andosols (299 ± 314 and 226 ± 378 μg/kg), but no clear relationships were found with soil CLD contents. Calculations of available CLD dissolved in the soil liquid phase using equations and soil datasets in the literature showed higher available CLD contents in Nitisols than in Andosols and a linear relationship between CLD available in soil and concentrations of CLD in wood, regardless of the type of soil. Trees growing on Nitisols are the plants most highly contaminated by CLD of all the plants in which this compound has been studied so far. With a plant-to-soil bioconcentration ratio around 150 l/kg, the consistent CLD uptake efficiency of the trees needs to be taken into account in further research for CLD remediation.; Le chlordécone (CLD), utilisé pour lutter contre le charançon du bananier Cosmopolites sordidus et libéré par des bananeraies polluées, continue de contaminer les écosystèmes des Antilles françaises. Les plantes comestibles ont été activement étudiées pour la prévention des risques, mais pas les arbres, alors même qu'ils pourraient jouer un rôle important dans les stratégies de dépollution. Les teneurs en CLD ont été analysées sur 24 arbres pionniers appartenant à 13 essences présentes dans des bananeraies abandonnées en Guadeloupe, sur trois sites contaminés sur nitisols (site 1) et andosols (sites 2 et 3). Des échantillons de bois ont été prélevés sur chaque arbre dans la partie basale du tronc et dans le sol à son pied. Leur teneur en CLD a été mesurée par le laboratoire d'analyses départemental de la Drôme (26) à Valence, France. Les teneurs moyennes en CLD dans la couche supérieure de 30 centimètres du sol des sites 1, 2 et 3 étaient respectivement de 2 543 ± 702, 5 251 ± 1 102 et 875 ± 865 µg/kg de sol sec. Parmi les arbres, 96 % étaient contaminés. La teneur en CLD des arbres poussant sur nitisols (3 406 ± 1 658 µg/kg de bois sec) était au moins cinq fois plus élevée que celle des arbres sur andosols (299 ± 314 et 226 ± 378 µg/kg), mais aucune relation nette n'a été établie avec la teneur en CLD du sol. Le calcul du CLD disponible dissous en phase liquide dans le sol, à l'aide d'équations et de séries de données pédologiques de la littérature, a montré des teneurs en CLD disponible plus élevées dans les nitisols que dans les andosols et une relation linéaire entre le CLD disponible dans le sol et les concentrations de CLD dans le bois, quel que soit le type de sol. Les arbres poussant sur nitisols sont les espèces végétales les plus fortement contaminées par le CLD parmi toutes celles dans lesquelles ce composé a été étudié jusqu'à présent. Avec un rapport de bioconcentration plante-sol d'environ 150 l/kg, l'efficacité soutenue d'absorption de CLD par les arbres doit être prise en compte dans les recherches futures sur la dépollution des milieux contaminés par le chlordécone.

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.

Biochemical reduction of nitrous oxide (N2O) to dinitrogen (N2) by N2O reductase (N2OR) is the only known sink to consume N2O. Copper (Cu) and pH are two key factors determining the activity of the enzyme N2OR. We hypothesized that changes in the Cu level could enhance the reduction of N2O to N2 in denitrifier strains and decrease the N2O emissions from agricultural soils. To test this hypothesis, Cu-modified culture medium was applied to denitrifier strains, and Cu-modified organic fertilizer was applied to both soil microcosms and fields. Of 46 denitrifier strains, 25 showed higher denitrifying activities and 30N2/(46N2O + 30N2) after the addition of Cu under pure culture conditions. Among 10 genera, Azospirillum and Herbaspirillum were the most responsive to the Cu level changes. The N2O flux was significantly reduced 4 or 8 days onwards after the application of 130 mM CuSO4-modified organic fertilizer (vol:wt = 1:1) into Andosol or Fluvisol, respectively, under soil microcosm conditions. In addition, the cumulative N2O emissions were significantly reduced after the application of 130 mM CuSO4-modified organic fertilizer. They were moderately reduced after the application of 130 mM CuSO4-modified organic fertilizer (vol:wt = 1:1) into a Fluvisol field. They were significantly lower in Azospirillum sp. UNPF1-inoculated soils after the application of 130 mM CuSO4-modified organic fertilizer when compared with that in dual non-inoculated and unmodified soils. Soils inoculated with Herbaspirillum sp. UKPF54 showed results similar to non-inoculated Fluvisol fields. These results suggest that Cu may enhance N2O conversion to N2 in denitrifiers and that Cu-modified organic fertilizer may enhance N2O consumption or decrease N2O emissions in agricultural soils.

A sediment trap with bamboo materials can be utilized as one alternative of eco-friendly technology to reduce the erosion that occurred on agricultural land. This study aims to determine the most efficient form of that sediment trap in the field. Location study is in the Tulungrejo Village, Batu, Indonesia, which has andosol soil type and 35 cases of a landslide in 2013. Three forms of sediment traps were used (square, trapezoidal, and stratified type) with the purpose to find the most effective form. It is obtained that the most effective sediment trap is a stratified form with the 31.91% effectiveness or able to withstand sediment of 25.02 kg, while the adequate number is two pieces with the ability to withstand the most considerable sediment of (91.70%). Therefore this stratified form of sediment traps is effective in erosion prevention on agricultural land in the study area. For further development, it is required to test out the variations of the contents in a broader area with a more varied level of the slope.

The discharge of domestic wastewater in urban areas without effective treatment may result in contamination of surrounding surface water. This study explored the wastewater treatment performance of multi-soil-layering (MSL) on domestic wastewater. Domestic wastewater parameter was use are Total Suspended Solids (TSS), Total Dissolved Solids (TDS), pH, Dissolved Oxygen (DO), Turbidity and Electrical conductivity (DHL). The experiment consisted of two stages, in stage 1, three partition in the reaktor was filled with layers of rock consisting of gravel, zeolite, and mix between gravel and zeolite. In stage 2, from the best results in stage 1, then added with stuffing mixture of andosol soil and coconut shell charcoal, mixture of andosol soil and sawdust and also mixture of andosol soil and rice straw charcoal. From the result it can be concluded that MSL with zeolite layer and mixture of andosol soil and coconut shell charcoal are the best result to purify the domestic wastewater. The efficiency for TSS, TDS, pH, DO, Turbidity and EC was 64.55%; 24.52%; 4.89%; 81.88%; 76.69% and 31,77% respectively.

The Galapagos archipelago has extensively been studied because of its geological and climatic setting and especially for its peculiar flora and fauna. However, there is still little information about its soils. The objective of this study was to investigate weathering and soil formation on Alcedo Volcano, which is the only volcano of Galapagos that has erupted abundant rhyolitic materials. Soils were sampled from three sites along an elevation/moisture gradient, site 1 at 872 m above sea level (a.s.l.) (humid zone), site 2 at 621 m a.s.l. (dry zone) and site 3 at 377 m a.s.l. (very dry zone). Soil pH (in H2O) ranged from 6.0 to 6.6 but did not vary significantly among the three sites. Water retention (at 1500 kPa) and phosphate retention increased with elevation/moisture. Similarly, soil organic carbon (SOC) stocks increased from approx. 1.1 kg m−2 in the very dry zone to approx. 7.5 kg m−2 in the humid zone. Allophane and ferrihydrite were the dominant colloidal constituents in the humid zone (site 1), whereas halloysite was found in the dry zone (site 2) and only traces of halloysite in the very dry zone (site 3). At site 1, the soil was borderline between andic and vitric properties and was classified as Silandic Tephric Andosol or Vitric Tephric Andosol for andic and vitric character, respectively; at site 2, the soil had vitric properties and was classified as Vitric Tephric Skeletic Andosol; and at site 3, the soil was borderline with respect to the expression of vitric properties and was classified as Vitric Tephric Skeletic Andosol in the presence and as Tephric Skeletic Regosol in the absence of vitric properties. Our results show that different moisture availability strongly affected SOC accumulation and favored the formation of different types of colloidal constituents (amorphous vs. crystalline) in the rhyolitic tephra of Alcedo Volcano. This has important bearings on the expression of andic and vitric soil properties and, hence, on the distribution of Andosols in the studied environment.

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.

Although chemical fertilizers have long been used to meet the high demand of nitrogen (N), the most common limiting nutrient to plant growth, the frequent use of this fertilizer gradually deteriorates soil fertility in addition to its high cost, lower supply and agronomic use efficiency in Ethiopia. Nevertheless, N-fixing cyanobacterial biofertilizers are eco-friendly, and currently considered important to support the developing organic agriculture. Therefore, this study was conducted to evaluate the potential of cyanobacterial biofertilizer for the growth and yield of three commonly growing crops in Ethiopia: maize, kale, and pepper under Alfisol and Andosol, and to investigate the potential contribution of cyanobacteria biofertilizer in selected soil fertility parameters. Three independent factorial experiments were conducted simultaneously in the greenhouse. Each experiment included a factorial combination of four nitrogen fertilizer sources applied at recommendation rate for each crop (control, urea, dried cyanobacteria, and liquid cyanobacteria,) and two soil types with acidic and alkaline pH (Alfisols and Andosols, respectively) arranged in a complete randomized design (CRD) with three replications. Application of dried and liquid cyanobacterial biofertilizer treatments significantly improves the soil N, soil organic carbon (SOC) and available P, Fe and Zn. Cyanobacteria treatments were also found to reduce or maintain the mean soil pH. Accordingly, maximum values of all the vegetative growth attributes of kale, and maize were obtained from the application of two comparable-fertilizer treatments: air-dried cyanobacteria and urea while for pepper crops only dried cyanobacteria. Concentrations of N, P, Zn, and Fe in leaves of kale, pepper, and maize were also significantly increased by air-dried cyanobacterial biofertilizer. Overall, dried cyanobacteria improved the growth and yield of the three crops, and the fertility of the soils. Therefore, the use of dry cyanobacterial biofertilizer could be recommended as a supplementary N source to inorganic fertilizer for kale, pepper and maize production in both study sites. Key words: Alfisols, andosols, biofertilizers, cyanobacteria, N-fixing.

To evaluate whether microbial stoichiometries of biomass and enzyme activity could vary in response to changes in nutrient availability in an arable soil during the crop growth period, temporal variation in nutrient availability, soil enzyme activities associated with carbon (C), nitrogen (N), phosphorus (P), and sulfur (S) acquisition, and microbial biomass C, N, and P were measured in an Allophanic Andosol amended with chemical fertilizer and cow manure. The ratio of l -asparaginase to β- d -glucosidase activities had a significant negative correlation with potentially mineralizable N. In addition, the ratio of arylsulfatase to β- d -glucosidase activities showed a significant negative correlation with available S. Thus, it seems plausible that microorganisms in the soil would allocate their resources to synthesis of N - and S-acquiring enzymes in response to variation in the nutrient availability caused by fertilization and over time. Also, the ratio of microbial biomass C/P had a significant negative correlation with available P, suggesting that this stoichiometry could reflect P availability in the soil. These results imply that microbial biomass and ecoenzymatic stoichiometries are useful for evaluating nutrient availability in soils.

Chemical and radiocesium concentrations in water and riverbed tufa of the Nigori River, flowing out of the southern foot of Mt. Asama volcano in central Japan, were investigated following the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. This tufa is characterized by porous and dense laminae. Its annual lamination (varve) is formed by seasonal changes in dissolved CO2 concentration in water with temperature, and the tufa calcite is mostly precipitated during summer. We analyzed radiocesium concentrations in ∼4-mm-thick tufa samples that included four or five varves collected after the fall in 2011–2014. The activity ratio of 134Cs/137Cs in tufa collected in 2011 and 2014 was 0.96 ± 0.01 and 0.99 ± 0.01, respectively, which implies radiocesium generated as a result of the FDNPP. Sequential extractions indicate that 137Cs in tufa collected in 2011 is occupied in exchangeable and carbonate phases (55.2% and 44.8%, respectively). The 137Cs concentrations equivalent to tufa calcite that were precipitated after 2011 showed variations similar to the amount of summer rainfall during 2011–2014, which may be attributed to increases in dissolved 137Cs concentrations in river water associated with intensified rainfall and microbial action over the summer. In contrast, the 137Cs sorbed to tufa calcite was not retained in the riverbed, and its migration may be attributed to the porous texture of tufa and the high flow rate of the river. Therefore, tufa calcite is easier to dissolve even though it adsorbs compared with other minerals (mica, andosol etc.).

Submerged rice cultivation is characterized by redox fluctuations and results in the formation of paddy soils, often accompanied by soil organic carbon (SOC) accumulation. The impact of redox fluctuations and the underlying soil type on the fate of organic carbon (OC) in paddy soils are unknown. Hence, we mimicked paddy soil development in the laboratory by exposing two soil types with contrasting mineral assemblages (Alisol and Andosol) to eight anoxic–oxic cycles over 1 year. Soils regularly received 13C-labeled rice straw. As control we used a second set of samples without straw addition as well as samples under static oxic conditions with and without straw. Headspaces were analyzed for carbon dioxide and methane as well as their δ13C signatures, whereas soil solutions were analyzed for redox potential, pH, dissolved iron, and dissolved organic carbon (DOC and DO13C). At the end of the experiment, when eight redox cycles were completed, mineral-associated organic matter (MOM) was isolated by density fractionation and characterized for δ13C, non-cellulosic carbohydrates, and lignin-derived phenols. Moreover, changes in the soil’s microbial community structure were measured. For both soil types, headspace data confirmed less respiration in straw-amended soils with redox fluctuation than in those under static oxic conditions. The δ13C data revealed that, irrespective of soil type, straw carbon allocation into MOM was larger in soils with redox fluctuation than in those with static oxic conditions. A net increase in MOM after the one-year incubation, however, was only observed in the respective Andosol, probably due to abundant reactive minerals capable of OC uptake. In the Alisol, straw OC most likely exchanged initial MOM. A potential for lignin accumulation in the MOM of soils incubated with straw and redox fluctuation was observed for both soil types. Lignin and carbohydrates suggest a plant origin of MOM formed under redox fluctuation. The initially similar bacterial community composition of the Alisol and Andosol changed differently under redox fluctuation. The stronger change in the Alisol indicates less protective microbial habitats. In summary, the overall turnover of straw OC in soils under redox fluctuation seems to be independent of soil type, while net accumulation of SOC as well as the evolution of the bacterial community structure may in part depend on soil type, suggesting an impact of the soil’s mineral composition.

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 root uptake of radiocaesium by different plant parts of Swiss chard (Beta vulgaris L. var. cicla), cabbage (Brassica oleracea L. var. capitata) and sweet corn (Zea mays L. var. saccharata ) and the potential influence of K-fertilising on the transfer behaviour was studied in allophanic volcanic soils (umbric andosol and dystric fluvisol) in Chile under temperate climate and heavy rainfall conditions (∼2660 mm y −1 ) over several vegetation periods. The soils were spiked homogeneously to 0.20 m depth with 100 kBq 134 Cs m −2 and activity concentrations measured. The transfer factor (TF, on a dry mass basis) to Swiss chard had a clear exponential decrease within each crop year for both soil types, either K-fertilised or unfertilised. The highest values of the TFs to Swiss chard were at the beginning of the harvests, and the half-times of TF decrease ranged between 52 and 137 d for umbric andosol and between 40 and 164 d for dystric fluvisol. Over the five seasons there was no consistent ageing effect based on TF in either soil types for the three studied crops. The effect of 134 Cs foliar uptake by Swiss chard from resuspended soil was estimated to account for about 70% (external leaves) and 30% (internal leaves) increase in the TF for the K-unfertilised umbric andosol, and showed an ambiguous behaviour for the K-fertilised umbric andosol. Consequently foliar uptake does not explain the 370 and 500% increase of the TF to Swiss chard leaves determined during the third growing period in the umbric andosol without and with K-fertilisation, respectively. Therefore an uncertainty factor of 3–5 is recommended to be taken into account when using this parameter for dose calculations. The TF to Swiss chard was found to be higher than previously reported values. The TF to cabbage and sweet corn plant parts was found to be within the range of previously reported values. Normal K-fertilisation resulted in about 2.4-fold reduction in 134 Cs TF to Swiss chard, 2.3-fold to sweet corn and 3.0-fold to cabbage.

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 phosphataseaddition 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., Article, Agronomy, 11(5): 903, 2021

BackgroundThe yield of potato (8.86 tonnes/ha), the second staple food and cash crop in Kenya is remained low due to a reduction in seasonal precipitation and low soil fertility. Drought or dry periods between rainfall seasons and increased temperatures, which leads to high crop evapotranspiration, are experienced in 70-80% of the smallholder farms. Among major elements require by potato, nitrogen is the most important influential element but it is deficient in most potato-growing soils in Kenya because of nutrient depletion with inadequate nutrient replenishment results from continuous production. Hence the introduction of supplemental irrigation with an adequate application of this nutrient could increase crop yields. Therefore, this study was conducted in Nakuru, one of the major potato growing areas in Kenya, to determine the effects of full supplemental irrigation (FI) and four nitrogen levels, N0(0), N1(60), N2(90) and N3(130 kg N/ha) on tuber yield, water use efficiency (WUE) and nitrogen use efficiency (NUE) of potato grown in a mollic Andosol in Kenya compared to conventionnel rain-fed potato production. Results The results showed that tuber yield, marketable tuber yield and NUE significantly differed due to the interaction effect between irrigation and N-fertilization rate (PConclusionsThe high potato yield and marketable tuber yield in mollic Andosol can be obtained when all water deficits of the growing season are eliminated with supplemental irrigation and an application of 130kg N/ha but it is essential to exploit water regimes for acceptable yield with water-saving.

Reduction of chemical fertilizers and effective use of livestock excrement are required for the realization of sustainable agriculture and reduction of greenhouse gas (GHG) emissions. The purpose of this study was to estimate the reduction rate of GHG emissions represented by comparing global warming potential (GWP) using organic fertilizers instead of chemical fertilizers. The study was conducted in a managed grassland on Andosol in southern Hokkaido for 3 years from May 2017 to April 2020. There were five treatment plots: no fertilizer, chemical fertilizer, manure, slurry, and digestive fluid. Organic fertilizers were applied such that the amount of NPK did not exceed the recommended application rate, and the shortage was supplemented with chemical fertilizers. Fluxes in CO2 caused by heterotrophic respiration (RH), CH4, and N2O were measured using the closed chamber method. Net ecosystem carbon balance (NECB) was obtained as net primary production + organic fertilizer application—RH—harvest. The GWP was estimated by CO2 equivalent NECB and CH4 and N2O emissions in each treatment. Chemical fertilizer nitrogen application rates in the organic fertilizer treatments were reduced by 10% for manure, 19.7% for slurry and 29.7% for digestive fluid compared to chemical fertilizer only, but the grass yields were not significantly different among the fertilizer treatments. The 3-year NECB showed significantly smallest carbon loss in manure treatment, and smaller carbon loss in the organic fertilizer treatments than in the chemical fertilizer only. The reduction rate in the GWP with use of organic fertilizers relative to that of chemical fertilizer was 16.5% for slurry, 27.0% for digestive fluid, and 36.2% for manure. The NECB accounted for more than 90% of the GWP in all treatments. CH4 emissions were < 0.1% of the GWP. On the other hand, N2O emissions accounted for more than 5% of the GWP, and was larger in the order of slurry > chemical fertilizer only > digestive fluid > manure. As a conclusion, these organic fertilizers can be used without no reduction of crop yield instead of chemical fertilizer, however, manure is the best way to increase soil carbon and to decrease GWP, followed by digestive fluid.

Urea is the most common nitrogen (N) fertilizer used in the tropics but it has the risk of high gaseous nitrogen (N) losses. Use of nitrification inhibitor has been suggested as a potential mitigation measure for gaseous N losses in N fertilizer-applied fields. In a field trial on a tropical Andosol pastureland in Costa Rica, gaseous emissions of ammonia (NH3) and nitrous oxide (N2O) and grass yield were quantified from plots treated with urea (U; 41.7 kg N ha-1 application-1) and urea plus the nitrification inhibitor nitrapyrin (U + NI; 41.7 kg N ha-1 application-1 and 350 g of nitrapyrin for each 100 kg of N applied) and control plots (without U and NI) over a six-month period (rainy season). Volatilization of NH3 (August to November) in U (7.4% ±1.3% of N applied) and U + NI (8.1% ±0.9% of N applied) were not significantly different (P > 0.05). Emissions of N2O in U and U + NI from June to November were significantly different (P < 0.05) only in October, when N2O emission in U + NI was higher than that in U. Yield and crude protein production of grass were significantly higher (P < 0.05) in U and U + NI than in the control plots, but they were not significantly different between U and U + NI. There was no significant difference in yield-scaled N2O emission between U (0.31 ±0.10 g N kg-1 dry matter) and U + NI (0.47 ±0.10 g N kg-1 dry matter). The results suggest that nitrapyrin is not a viable mitigation option for gaseous N losses under typical N fertilizer application practices of pasturelands at the study site. Organismo Internacional de Energía Atómica/[No.CRP D1.50.16]/IAEA/Austria Organización de las Naciones Unidas para la Alimentación y la Agricultura/[No.COS5031]/FAO/Italia Universidad de Costa Rica/[802-B7-505]/UCR/Costa Rica Universidad de Costa Rica/[802-B5-138]/UCR/Costa Rica UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro en Investigación en Contaminación Ambiental (CICA) UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Estación Experimental de Ganado Lechero Alfredo Volio Mata (EEAVM)

The Philippines' agriculture sector continues contributing to country-wide soil trace gas emissions; however, field-based estimation of emissions from this sector remains inadequate. While there’s a need to increase crop production to provide for a fast-increasing population, it is equally essential to reduce greenhouse gases (GHG) from agricultural production to protect the environment. A reliable assessment of soil GHG is a requisite to attain these, thus the present study. We conducted spatially replicated quantification of soil greenhouse gas fluxes, i. e. N2O, CH4, and CO2, with monthly measurements from May 2018 to May 2019, as well astheirsoil controlling factors in nine plots of secondary forest and ten farms, all on comparable Andosol soil in Leyte Island, the Philippines. The management practices of these vegetable farms were those implemented by the farmers, and our measurements were carried out on these actual farm practices, reflecting their commonly varied fertilization rates (200 – 610 kg N ha-1 cropping period-1 with 2 – 3 cropping periods each year). Soil N2O emissions from vegetable farms were larger than the forest (P ≤0.01) and were stimulated during the dry than the wet season (P ≤0.01). Its temporal variation was mainly driven by soil NO3– (r = 0.52, P ≤0.01). Large stocks of soil extractable NO3– in the top 50 cm (9250 ± 2830 mg N m–2, mean ± SE) and 50 – 100 cm soil depth (11255 ± 5980 mg N m–2) supported the substantial soil N2O emissions from these vegetable farms, which were larger than those from other agricultural areas in South East Asia on similar soil and climate. These small-scale vegetable farms had annual fluxes of 12.7 ± 2.6 kg N2O–N, –1.1 ± 0.1 kg CH4–C and 11.6 ± 0.7 Mg CO2–C ha-1 yr-1, whereas the secondary forest as reference land use had 0.10 ± 0.02 kg N2O–N, –2.0 ± 0.2 kg CH4–C, and 8.2 ± 0.7 Mg CO2–C ha-1 yr-1. The forest had larger soil CH4 uptake than the vegetable farms (P ≤0.01). For the forest, CH4 uptake was positively correlated with soil moisture (r = 0.60, P ≤0.01), suggesting diffusion limitation of atmospheric CH4 into the soil and/or soil CH4 production during high rainfall months. For the vegetable farms, CH4 uptake was negatively correlated with both soil NO3– and NH4+ (r = –0.46, P ≤0.01), suggesting CH4 consumption enhanced by mineral N. Soil CO2 emissions were higher in vegetable farms relative to the forest (P ≤0.01), reflecting the former’s reduced soil organic carbon stocks in the top 1 m (P ≤0.01) but compensated with regular application of chicken manure (460 – 1940 kg C ha-1 cropping period-1) as organic fertilizer. Our study expounded understanding on the extent of changes in soil GHG from an Andosol soil that underwent land-use conversion. Such data will be beneficial in developing sound management and policy strategies for reducing soil GHG fluxes from this economically vulnerable agricultural sector.

Appropriate application of organic fertilizer is required to reduce environmental impact from grassland and to achieve sustainable livestock production. However, N2O fluxes from soil increase mainly due to changes in soil environmental factors such as temperature, moisture, soil pH and soil mineral nitrogen content, immediately just after fertilization, and it may be different among the types of fertilizer. In this study, we investigated that how N2O fluxes are influenced by the application of three types of organic fertilizer (manure, slurry, and digestive fluid) for 4 years in a grassland on Andosol in southern Hokkaido, Japan. Five treatment plots: no fertilizer, chemical fertilizer, manure, slurry, and digestive fluid were established in a managed grassland in Shizunai Livestock farm, Hokkaido University. Fertilizers were applied in late April every year from 2017 to 2020. Organic fertilizers were applied such that the NPK not exceed the regional recommendation rate, and the shortage was compensated by chemical fertilizer. N2O flux was measured by using a closed chamber method. At the same time of the flux measurements, soil temperature at 5 cm soil, and soil moisture (WFPS), soil pH, NO3-N contents in 0-5 cm soil were measured to see the relationship with N2O fluxes.In 2017, a large peak of N2O flux was observed in slurry plot (195.8μg m-2h-1) and digestive fluid plot (347.8 μg m-2h-1), whereas in 2018 and 2019, there were no large peak after the fertilization at all plots, however, in 2020, a large peak of N2O flux was observed in manure plot (472.7 and 475.7μg m-2h-1) and slurry plot (194.9μg m-2h-1). These peaks of N2O flux were significantly larger than those in no fertilizer and chemical fertilizer plots. All N2O flux peaks were observed when the soil temperature ranged 10-14 ℃. In 2017 and 2020, a large peak of N2O flux was observed although WFPS was always above 80% which is the soil moisture level leading to the complete denitrification. There was a negative relationship between N2O flux and soil pH. Low soil pH might reduce the N2O reductase activity, leading to the large peak of N2O flux at high WFPS above 80%. In addition, there was a positive relationship between N2O flux and soil NO3--N contentin 2017 and 2020. However, in 2018 and 2019, when WFPS was below 80% in most days, there was no positive relationship between N2O flux and soil NO3--N content. In conclusion, the peak of N2O flux was different depending on the year and fertilizer, In order to reduce N2O flux just after fertilization, it is especially important not to lower the soil pH and not to increase the WFPS.

In order to examine the hypothesis that the soil microbial community in a nitrogen-limited forest responds to moderately elevated nitrogen deposition (< 10kg N ha-1 yr-1), correlations between nitrogen 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. Nitrogen deposition in each plot was measured from May to November 2018. In August 2018, litter and surface soil samples were collected from all plots to measure net nitrogen mineralization and nitrification rates as indicators of microbial activity, and microbial biomass and various gene abundances (i.e., bacterial 16S rRNA, fungal ITS, and bacterial and archaeal amoA genes) as indicators of microbial abundance. Nitrogen deposition in forest edges was 1.4-fold greater than that in forest interiors, whereas maximum deposition was 3.7 kg N ha−1. Nitrogen deposition was significantly correlated with net nitrogen mineralization and nitrification rates and 16S rRNA and bacterial amoA gene abundances. Microbial community structures analyzed for bacterial 16S rRNA and fungal ITS gene amplicons were different between litter and soil samples, but were similar between the forest edge and interior. Nitrogen deposition was also correlated with the soil carbon-to-nitrogen ratio and nitrate and ammonium contents. Thus, it was suggested that some soil microbial activities and abundances in a nitrogen-limited forest likely responded to moderately elevated nitrogen deposition. These findings provide primary information on soil microbial response to moderately elevated nitrogen deposition.

El alofán es una nanopartícula natural presente en suelos de origen volcánico como los andisoles, que se encuentran distribuidos alrededor de todo el mundo en países con actividad volcánica. En Ecuador, los andisoles constituyen el 30% del territorio en zonas altas y húmedas de la región sierra-norte. El alofán se puede obtener de los andisoles a través de procesos físicos y químicos, o a su vez se puede sintetizar. Este nanomaterial posee múltiples propiedades para varias aplicaciones en diferentes áreas. Existen muchas investigaciones de estas nanopartículas y de este tipo de suelos, pero no se han estudiado aún en el Ecuador. En este artículo se presentan las características estructurales, propiedades, la formación, aislamiento, síntesis y usos del alofán, con el fin de generar conocimiento e incentivar la investigación de estos suelos que son fuente de la mencionada nanopartícula. La búsqueda de literatura se realizó en bases de datos de Science Direct y Google Académico, y se utilizaron artículos de alto impacto relacionados con investigaciones de alofán natural o sintético. Las características particulares que tiene el alofán le permite ser usado como remediador ambiental, bactericida, antiinflamatorio, ignífugo, soporte de enzimas, pero además se ha estudiado en catálisis, fotocatálisis y electrocatálisis. Al considerar el área cubierta por el alofán en el territorio ecuatoriano y su disponibilidad, este se puede aprovechar para realizar investigaciones basadas en los estudios internacionales que se han desarrollado para aprovechar en el área ambiental y médica.// 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.

The Kenya Great Rift Valley (KGRV) region unique landscape comprises of mountainous terrain, large valley-floor lakes, and agricultural lands bordered by extensive Arid and Semi-Arid Lands (ASALs). The East Africa (EA) region has received high amounts of rainfall in the recent past as evidenced by the rising lake levels in the GRV lakes. In Kenya, few studies have quantified soil loss at national scales and erosion rates information on these GRV lakes&rsquo, regional basins within the ASALs is lacking. This study used the Revised Universal Soil Loss Equation (RUSLE) model to estimate soil erosion rates between 1990 and 2015 in the Great Rift Valley region of Kenya which is approximately 84.5% ASAL. The mean erosion rates for both periods was estimated to be tolerable (6.26 t ha&minus, 1 yr&minus, 1 and 7.14 t ha&minus, 1 in 1990 and 2015 respectively) resulting in total soil loss of 116 Mt yr&minus, 1 and 132 Mt yr&minus, 1 in 1990 and 2015 respectively. Approximately 83% and 81% of the erosive lands in KGRV fell under the low risk category (&lt, 10 t ha&minus, 1) in 1990 and 2015 respectively while about 10% were classified under the top three conservation priority levels in 2015. Lake Nakuru basin had the highest erosion rate net change (4.19 t ha&minus, 1) among the GRV lake basins with Lake Bogoria-Baringo recording annual soil loss rates &gt, 1 in both years. The mountainous central parts of the KGRV with Andosol/Nitisols soils and high rainfall experienced a large change of land uses to croplands thus had highest soil loss net change (4.34 t ha&minus, 1). In both years, forests recorded the lowest annual soil loss rates (&lt, 3.0 t ha&minus, 1) while most of the ASAL districts presented erosion rates (&lt, 8 t ha&minus, 1). Only 34% of all the protected areas were found to have erosion rates &lt, 1 highlighting the need for effective anti-erosive measures.

Sclerotia grains, fungal resting structures, are commonly found in forest soils, but little is known of their chemical characteristics. Sclerotia samples collected from a buried A horizon from a Japanese Andosol were physically and chemically characterized by scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), Fourier-transform infrared spectrometry, elemental (C-H-N-O) analysis, 13C nuclear magnetic resonance, 27Al nuclear magnetic resonance, particle induced X-ray emission spectrometry, inductively coupled plasma optical emission spectrometry, and inductively coupled plasma mass spectrometry. The C, H, N, and O contents of the sclerotia grains were determined to be 47.6, 3.32, 0.78, and 30.2% by mass, respectively. Sclerotia Al, Fe, and Si contents determined by particle induced X-ray emission analysis were 1.4, 0.56, and 0.08%, respectively, in relative agreement with those determined by inductively coupled plasma optical emission spectrometry (1.1, 0.5, and 0.1%, respectively). Functional carbon groups were characterized by dominance of O-alkyl carbon associated with aromatic carbon. Analysis of the 27Al nuclear magnetic resonance spectra showed the presence of 6- and 4-coordinated aluminum. X-ray diffraction analysis showed that the dominant form of aluminum in sclerotia was amorphous. Minor elements such as Ti, Cr, Mn, Cu, Zn, Br, and Pb were detected in the grains at concentrations between 10 and 100 μg g−1.