Volcanic Soils Research Articles

'We no longer experience the same pain': a cross-sectional study assessing the impact of Heart and Sole Africa's podoconiosis prevention education program.

Podoconiosis is a non-infectious neglected tropical disease caused by long-term exposure to irritant volcanic soils. It results in severe physical, psychological and financial consequences. Heart and Sole Africa (HASA) is a non-governmental, community-based organization providing management to podoconiosis patients in Rwanda. We sought to analyze the impact of their program on the lives of patients. Quantitative surveys recorded the participants' demographics, adherence to HASA's management recommendations and changes in quality of life (QOL). Qualitative questions were used to gather respondent perspectives on HASA programming. We interviewed 127 patients from HASA's Musanze (n=47) and Burera (n=80) clinics. Almost all participants (98.4%) reported statistically significant (p<0.01) improvements in their QOL, and more than one-half (51.2%) had a favorable adherence score of >80%. Qualitative feedback identified specific challenges to adherence and recognition of program success in symptom management. Our study demonstrated the value of community-based podoconiosis programming in improving the lives of patients. Practices such as regular feet washing, emollient application, shoe wearing and limb raising can result in a marked reduction of morbidity. Our findings support the argument for scaling up these management practices across Rwanda.

Old basalts, young soils ‐ Age constraints for the Golan Heights plateau volcanic soils

AbstractThe Golan Heights plateau in northern Israel is underlaid by volcanic rocks ranging in age from ~5.5 to 0.1 Ma. Throughout the Golan Heights, these rocks are covered by shallow soils that rarely exceed 0.5 m in depth. The soils are generally assumed to form a chronosequence, in which their ages correspond to those of the basalts they cover. Such age correspondence would imply that the soils have been slowly accumulating over hundreds of thousands to a few million years, suggesting a generally stable system. The ages of these soils and their temporal correlation to the basalts, however, have never been determined or tested.Here, we present age constraints for the soils of the Golan Heights. Soils were surveyed and sampled with their corresponding basalt bedrock. Mass balance calculations based on conservative immobile elements, coupled with 36Cl‐based basalt denudation rates, suggest that the soil ages are decoupled from the ages of the underlying basalts, and represent up to a few thousand years of soil production, at most. This time frame is orders of magnitude shorter than the basalt age, challenging the prevalent assumption that the soils form a chronosequence.Our findings strongly suggest that erosion is a significant factor controlling soil formation and accumulation on the plateau, despite the generally flat morphology of the Golan Heights. The erosion is associated with tectonic activity along the Dead Sea transform, with the development of the Kinarot and Hula valleys, and with the consequential development of drainage systems of various sizes on the plateau. Throughout the Golan Heights, the timing of volcanic activity in relation to the development of the valleys and drainage systems also appears to strongly affect soil development and accumulation.

High levels of cadmium altered soil archaeal activity, assembly, and co-occurrence network in volcanic areas

Soil microbial communities are essential to biogeochemical cycles. However, the responses of microorganisms in volcanic soil with high heavy metal levels remain poorly understood. Here, two areas with high levels of cadmium (Cd) from the same volcano were investigated to determine their archaeal composition and assembly. In this study, the Cd concentrations (0.32–0.38 mg/ kg) in the volcanic soils exceeded the standard risk screening values (GB15618–2018) and correlated with archaeal communities strongly (P < 0.05). Moreover, the area with elevated levels of Cd (periphery) exhibited a greater diversity of archaeal species, albeit with reduced archaeal activity, compared to the area with lower levels of Cd (center). Besides, stochastic processes mainly governed the archaeal communities. Furthermore, the co-occurrence network was simplest in the periphery. The proportion of positive links between taxa increased positively with Cd concentration. Moreover, four keystone taxa (all from the family Nitrososphaeraceae) were identified from the archaeal networks. In its entirety, this study has expanded our comprehension of the variations of soil archaeal communities in volcanic areas with elevated cadmium levels and serves as a point of reference for the agricultural development of volcanic soils in China.

Assessment of Fertility Dynamics and Nutritional Quality of Potato Tubers in a Compost-Amended Mars Regolith Simulant.

Mars exploration will foresee the design of bioregenerative life support systems (BLSSs), in which the use/recycle of in situ resources might allow the production of food crops. However, cultivation on the poorly-fertile Mars regolith will be very challenging. To pursue this goal, we grew potato (Solanum tuberosum L.) plants on the MMS-1 Mojave Mars regolith simulant, pure (R100) and mixed with green compost at 30% (R70C30), in a pot in a cold glasshouse with fertigation. For comparison purposes, we also grew plants on a fluvial sand, pure (S100) and amended with 30% of compost (S70C30), a volcanic soil (VS) and a red soil (RS). We studied the fertility dynamics in the substrates over time and the tuber nutritional quality. We investigated nutrient bioavailability and fertility indicators in the substrates and the quality of potato tubers. Plants completed the life cycle on R100 and produced scarce but nutritious tubers, despite many critical simulant properties. The compost supply enhanced the MMS-1 chemical/physical fertility and determined a higher tuber yield of better nutritional quality. This study demonstrated that a compost-amended Mars simulant could be a proper substrate to produce food crops in BLSSs, enabling it to provide similar ecosystem services of the studied terrestrial soils.

Evidence for immune activation in pathogenesis of the HLA class II associated disease, podoconiosis

Available evidences suggest that podoconiosis is triggered by long term exposure of bare feet to volcanic red clay soil particles. Previous genome-wide studies in Ethiopia showed association between the HLA class II region and disease susceptibility. However, functional relationships between the soil trigger, immunogenetic risk factors and the immunological basis of the disease are uncharted. Therefore, we aimed to characterise the immune profile and gene expression of podoconiosis patients relative to endemic healthy controls. Peripheral blood immunophenotyping of T cells indicated podoconiosis patients had significantly higher CD4 and CD8 T cell surface HLA-DR expression compared to healthy controls while CD62L expression was significantly lower. The levels of the activation markers CD40 and CD86 were significantly higher on monocytes and dendritic cell subsets in patients compared to the controls. RNA sequencing gene expression data indicated higher transcript levels for activation, scavenger receptors, and apoptosis markers while levels were lower for histones, T cell receptors, variable, and constant immunoglobulin chain in podoconiosis patients compared to healthy controls. Our finding provides evidence that podoconiosis is associated with high levels of immune activation and inflammation with over-expression of genes within the pro-inflammatory axis. This offers further support to a working hypothesis of podoconiosis as soil particle-driven, HLA-associated disease of immunopathogenic aetiology.

The normalized difference vegetation index value of volcanic paddy soils of Mt. Talang using Landsat 8 image

Abstract Accurate and up-to date information on the spatial distribution of paddy fields in volcanic soils is important. The volcanic soil in West Sumatra covers an area about 602.500 ha. Soils of volcanic origin are considered fertile and productive soils. They are widely used to grow annual and perennial crops. Paddy cultivation in volcanic soils is commonly practiced in West Sumatra. Remote sensing data can be used to observe the condition of rice plants in volcanic soils from by calculating the vegetation index value through the NDVI (Normalized Difference Vegetation Index). This study aims to determine the vegetation index of paddy grows in Mt. Talang by using Landsat 8 satellite imagery and correlate the index value with the total carbon and fractions content. Soil samples were collected using the 1x1 km interval grid method from 5099,78 ha of volcanic paddy fields. Soil samples were collected undisturbed and disturbed condition. The undisturbed soil samples were used to analyze bulk density (BD). The disturbed soil samples were dried and sieved with a 2-mm sieve and then analyzed for soil pH (H20 and KCl), Organic C, Labile C, and Very Labile C. All of soil samples have low bulk density (0.76-0.89 Mg/m3). Soil pH is considered neutral (6.50 to 6.93). The average vegetation index value was high, with a maximum value of 0.60 and a minimum value of 0.39. The results of the regression analysis showed that there was no relationship between NDVI and soil chemical properties. Determination of the vegetation index during the growing period of paddy is very useful to improve the accuracy of paddy identification sites at the regional scale and to predict the potential paddy production in due time.

Mapping of volcanic soil chemical properties with digital soil mapping after the prolonged eruption of Mt. Sinabung (2013-2020)

Volcanic soils in Indonesia cover an area of about 5.4 million ha and around 2.7 million ha in Sumatra. The prolonged eruptions of Mt. Sinabung in North Sumatra from 2013 to today eject pyroclastic materials, which blanketed and altered the soil surface. As a result, volcanic soil formed from these pyroclastic deposits. This study aims to map the chemical properties of volcanic soils after the prolonged eruption of Mt. Sinabung from 2013-2020. Thirty-four soil samples were collected at a depth of 0-20 cm according to the grid sampling system with an interval of 1x1 km covering an area of about 4,500 ha. Regression kriging (RK) was applied to predict the soil’s chemical properties and distribution spatially. The soil samples were air dried, sieved, and analyzed to determine soil pH (H2O and KCl), available, potential and retention P, organic carbon, total nitrogen, cation exchange capacity (CEC), and exchangeable basic cations. Soil pH (H2O) ranges from very acidic to neutral (4.14-6.52) and very acidic to acidic pH (KCl) (3.89-5.26), low to very high available-P (3.46-382.01 ppm), potential-P very low to very high (3.76-230.26 mg 100g-1), P-retention is categorized as very high (90-99%). The organic Carbon range from low to very high (1.73-13.05%), low to high total nitrogen (0.13-0.60%), low to high cation exchange capacity (11.78-97.71 cmolc kg-1), and exchangeable base cations are categorized as high with K values (1.60-2.98 cmolc kg-1). Na (3.72-7.45 cmolc kg-1) and Mg (5.79-12.15 cmolc kg-1) were categorized as high and Ca very low (0.039-0.157 cmolc kg-1). The estimated area of soils with pH between 4 and 5 is about 424.85 ha, and soils with pH between 5 and 6 covered an area of approximately 3,964.81 ha. Our findings suggest that persistent eruptions of Mt. Sinabung supply new plant nutrition, which can enrich and increase soil fertility in the future.

Digital mapping of soil organic carbon in volcanic soils after prolonged eruption Mt. Sinabung, Karo Regency, North Sumatra, Indonesia

Mount Sinabung (at Karo Regency, North Sumatra) has been considered as an active volcano since 2010, and after three years of inactivity, the volcano’s activity resumed in 2013. The deposition of volcanic ash buried everything on the soil surface with various thicknesses. Volcanic ash is a valuable inorganic material and consists mostly of primary minerals. But with time, these materials can initiate carbon storage through the revegetation process. This study investigates carbon storage and sequestration in volcanic soils affected by the intermittent eruptions of Mt. Sinabung. A total of 34 soil samples were collected from areas of 3 to 7 km from the eruptive vent. The samples were analyzed to determine labile-C, very labile-C, total-C, Organic-C, non-crystalline-C, and metal complex-C fractions. Regression kriging (RK) was applied to spatially predict the carbon distribution. The results showed that the highest labile-C was 1.65% found in the Southeast slope and the lowest, 1.20%, in the Southern slope. The highest value of very labile-C was in the Southeast (1.20%), and the lowest was in the Northern (0.46%). The highest (11.66%) and lowest values (8.84%) of total C were in the Northeast and South slopes, respectively. The highest Organic-C value was detected 7.42% in the Northeast volcanic soils, and the lowest, 5.74%, is in the South slopes soil. The lowest non-crystalline- C was found in the soils of Northeast slope (0.60%), and the highest was in the Southeast (0.82%) soil. While the highest metal complex-C value was 0.88% in the Southeast, and the lowest is 0.36% in the soil of South slope. These data show that the highest carbon storage is parallel with the direction of the ash distribution, which tends to the Southeast side of Mt. Sinabung. The results of this study demonstrated that volcanic regions have a strong resilience capacity to bounce back after devastating natural hazards. Volcanic deposits interact with atmospheric water to initiate vegetation regrowth and create a carbon pool within their particles.

Influence of faults on mineralogy and geotechnical characteristics of Tropical Volcanic Residual Soils (TVRS) concerning environmental issues and regional development, Case Study: West Lampung Transect Road, Sumatra, Indonesia

Hydrothermal alteration occurs in andesitic rocks in the study area due to the presence of the Great Sumatran Fault. This study shows the consequences of this phenomenon on the characteristics of volcanic residual soils. This study comprises volcanic residual soils formed from the same andesitic rocks in a site located in West Lampung, Sumatra, Indonesia which has a tropical climate. Chemical, physical, and mineralogical characterizations were carried out to describe the materials and the changes imposed by their alteration. Effects of alteration on the soil’s behavior were assessed in terms of plasticity.

Disentangling the effects of temperature and reactive minerals on soil carbon stocks across a thermal gradient in a temperate native forest ecosystem

Effects of global warming on soil organic carbon (C) can be investigated by comparing sites experiencing different temperatures. However, observations can be affected by covariance of temperature with other environmental properties. Here, we studied a thermal gradient in forest soils derived from volcanic materials on Mount Taranaki (New Zealand) to disentangle the effects of temperature and reactive minerals on soil organic C quantity and composition. We collected soils at four depths and four elevations with mean annual temperatures ranging from 7.3 to 10.5 °C. Soil C stocks were not significantly different across sites (average 162 MgC ha−1 to 85 cm depth, P > .05). Neither aluminium (Al)-complexed C, nor mineral-associated C changed significantly (P > .05) with temperature. The molecular characterisation of soil organic matter showed that plant-derived C declined with increasing temperature, while microbial-processed C increased. Accompanying these changes, soil short-range order (SRO) constituents (including allophane) generally increased with temperature. Results from structural equation modelling revealed that, although a warmer temperature tended to accelerate soil organic C decomposition as inferred from molecular fingerprints, it also exerted a positive effect on soil total C presumably by enhancing plant C input. Despite a close linkage between mineral-associated C and soil organic C, the increased abundance of reactive minerals at 30–85 cm depth with temperature did not increase soil organic C concentration at that depth. We therefore propose that fresh C inputs, rather than reactive minerals, mediate soil C responses to temperature across the thermal gradient of volcanic soils under humid-temperate climatic conditions.

Genesis, mineralogy, and geochemistry of soil profiles developed on volcanic materials under semi-arid conditions from Central Anatolia-Turkey

Pedogenesis of volcanic soils has been studied broadly in humid regions, but very little data are present regarding these soils in arid and semi-arid regions of Turkey. This research aimed to assess the pedological processes and investigate the physical, chemical, and mineralogical characteristics of soil profiles developed from volcanic parent material. The studied soils were not classified as Andisol because they lack andic properties. The results showed that sand and coarse silt fractions exceeded 30%. The bulk density was higher than 0.90 grcm-3 in all profiles. In general, phosphate retention was low, higher than 25% in profiles but lower than 85% in all profiles. The Al + ½ Fed percentages were lower than 2% in all profiles. Selective extraction (Na–Pyrophosphate, Ammonium Oxalate, Na–Dithionite) indicated that soils lack noncrystalline minerals, such as allophane, imogolite, and iron humus complexes. The only noncrystalline minerals in high quantities are Al-humus complexes and small amounts of ferrihydrite. X-ray diffraction indicated that smectite, kaolinite and illite were dominant minerals in the clay fraction. Among the studied profiles, profiles 1 and profile 4 are classified as vitrandic Haploxerept, profile 2 as vitrandic haploxerolls, and profile 3 as vitrandic Xerorthent. The results indicated that the dominant soil-forming processes include the following: 1. desilication and the eluviations of base cations and Al from the solum; and 2. transformation of iron and aluminum from the sand and silt-size fractions into secondary clay and crystalline Fe minerals. The major factors determining soil genesis on Mt. Karacadağ appear to be climate and topography affected by the leaching regime and weathering rates.

Effect of the incorporation of ashes from the Calbuco volcano on the porous function of an andosol

Soils derived from volcanic ashes represent >60% of the arable land in Chile. Permanent volcanic activity makes seeking solutions for the management of volcanic material deposited after an eruption essential. The aim of this research was to evaluate how incorporating ashes from the eruption of the Calbuco Volcano affected the structure of a volcanic soil in southern Chile. Undisturbed soil samples were collected in 2022, under three field conditions: soils from which the ashes were entirely removed after the eruption (c), soils in which the ashes were incorporated (c/i) and soils on which the ashes remained on the surface (s/i). The pore-size distribution and the air conductivity were determined based on the water retention curve (WRC), the coefficient of linear extensibility (COLE), the pore shrinkage index (PSI) and the air permeability (Ka). Under c/i field conditions, an increase in total porosity (TP) of 5.57 and 3.48% was found when compared to the control and s/i field conditions, respectively. The highest volume of plant available water capacity (PAWC) was observed in the s/i field conditions, which increased by 65% compared to the other soil conditions. The incorporation of ash into the first 20 cm of depth did not guarantee an increase in usable water for plants; nonetheless, changes in structure did generate a redistribution in the pore size. Therefore, it is essential to evaluate how volcanic ash deposits and their incorporation affect soil physical properties under field conditions.

Karakterisasi Tanah Vulkanik di Kabupaten Kediri, Jawa Timur, Indonesia Berdasarkan Uji CPT, SPT, dan PMT

Indonesia is a country surrounded by the Pacific Ring of Fire so that various areas are dominated by volcanic soil. Volcanic soils have unique and unusual characteristics, different structures and properties from soil in general, and are strongly influenced by geological processes. Volcanic soils were also found to be problematic and caused a lot of geotechnical damage. Research on volcanic soils from a geotechnical perspective in Indonesia is still very limited. This study aims to characterize volcanic materials in Kediri Regency, East Java, Indonesia, based on in situ testing using CPT (Cone Penetration Test), Standard Penetration Test (SPT), and Pressuremeter Test (PMT). CPT and SPT are the most common and frequently used field tests, while PMT is used to obtain horizontal stresses. Some data from the X-Ray Diffraction Analysis (XRD) test and corebox drilling results will also be used in this study. Field test results will display soil classification and parameters, which will then be combined, and empirical correlations will be obtained for site characterization as well as comparisons with other volcanic soil literature studies. The results showed that the volcanic soil in Kediri Regency consists of non-lateritic to lateritic soil. Based on the CPT and SPT correlations, it was found that the qc/N value was greater than in general soils for both cohesive and non-cohesive soils. The authors also found a relationship between parameters and interpretation of PMT data against NSPT for cohesive volcanic soils in the study area.

Dampak Penggunaan dan Pengolahan Tanah dalam Usahatani Sayuran Terhadap Infiltrasi Tanah Andisol di Kabupaten Kerinci

Andisol is a volcanic soil with a medium texture and a high organic matter content, so it is generally loose. However, the majority of vegetable farmers in Kayu Aro Barat District, Kerinci Regency carry out intensive soil cultivation in intensive land use (planting throughout the year, 2-3 times/year). Unfortunately, the role of tillage in soil and water conservation (SWC) is almost non-existent and even detrimental. One approach in SWC is the application of conservation tillage to control soil compaction so that soil infiltration is maintained. The research aims to determine the rate and capacity of Andisol soil infiltration and several factors that influence it, due to differences in the intensity of land use and cultivation in vegetable farming in Kebun Baru Village, Kayu Aro Barat District. The research used an exploratory-descriptive survey method. Observation and soil sampling points were determined using purposive stratified random sampling covering flat to sloping land, intensive land use and cultivation (planting 2-3 times/year + land cultivation 2 times/year), semi-intensive (planting 1-2 times/year + land cultivation once/year), and non-intensive (planting 1-2 times /year + land cultivation once/2 years), each land is planted with potatoes every year with various planting patterns. Soil infiltration rate was measured using a Double Ring Infiltrometer, and infiltration capacity was estimated using the Horton Equation. Soil infiltration rate and capacity are respectively 26.5 cm/hour (very fast) and 8.12 cm/hour (as is the infiltration capacity of loam-textured soil in general) on flat land with intensive land use and cultivation; much larger than other fields. On the other hand, the infiltration rate and capacity were 6.68 cm/hour (medium) and 2.27 cm/hour respectively (smaller than the infiltration capacity of silty loam soil in general), and the smallest, on sloping land that was used and cultivated not intensively. It is necessary to educate farmers to cultivate the land as necessary according to the characteristics of the soil and plant needs, to maintain the sustainability of soil function and building sustainable vegetable farming in West Kayu Aro District, Kerinci Regency.

Comparative incidence of Ganoderma basal stem rot and upper stem rot disease in oil palm in relation to soil type and geographical distribution

The greatest danger to oil palm sustainability in Indonesia is posed by basal stem rot (BSR) and upper stem rot (USR). However, information on their comparative incidence in relation to soil types and geo-distribution remains scarce. As such, data from annual surveys carried out over 95,000 ha of first-generation oil palms planted in Asian Agri estates was reviewed and analyzed. The highest infection levels occurred in North Sumatra, followed by Riau and Jambi. Likewise, infection levels were highest in peat (24.79 palms/ha), followed by alluvial (13.41 palms/ha), volcanic (7.25 palms/ha), and inland (0.07 palms/ha) soil types. Averaged over three provinces and all four soil types, infection due to USR was more dominant than BSR, comprising 52.3% and 47.7%, respectively. Molecular assays of infected tissue confirmed that both BSR and USR were caused by the genus Ganoderma with the major species being G. boninense. Longitudinal dissections of oil palm trunks infected by USR indicated no infection connectivity with the basal portion of the trunk, unlike BSR, where the infection is through root contact. Transmission through basidiospores is likely to play an essential role in USR epidemiology. Understanding pathogen distribution, species identity, and its transmission epidemiology are prerequisites to control diseases more effectively.

Topsoil's magnetic and electrical properties in a volcanic and tropical region.

Environmental monitoring by measuring topsoil's magnetic and electrical properties is one practical, quick, and low-cost approach. This method has been used worldwide as a proxy for the presence of potentially toxic elements. However, additional research must be conducted on diverse soil types, geology, and climates. We determined the magnetic and electrical properties of urban and agricultural topsoils in a volcanic region and analyzed them as possible proxies of potentially toxic elements for environmental monitoring. To identify topsoil characteristics, we employed the measurements of magnetic susceptibility and hysteresis, electrical conductivity, total dissolved solids, power of hydrogen (pH), particle morphology, and element contents that were statistically analyzed to identify relevant properties. The result was able to differentiate volcanic soils from urban, industrial, and agricultural areas as well. The value of low-frequency magnetic susceptibility (χLF) in soils from urban areas is higher than 866.0±249.9 ×10-8 m3 kg-1, while the value of χLF in agricultural areas is 208.0±67.8 ×10-8 m3 kg-1. This is reinforced by the relationship between low-frequency and frequency-dependent magnetic susceptibility (χLF-χFD%) in samples from urban areas that fall within the same cluster dominated by coarse-grained magnetic minerals originating from anthropogenic processes. In contrast, the agricultural area forms a separate cluster primarily influenced by pedogenic processes from acid igneous rock minerals. Caution is required for interpreting the magnetic signal due to the high contents of lithogenic magnetic particles inherited from the parent materials of Andisols.

Distribution and potential contamination assessment of rare earth elements (REE) in Indonesian volcanic soil

Rare earth elements (REE) are essential elements used in various products. Meanwhile, in several countries, REE is feared will pollute the ecosystem. The occurrences of REE in soil depend on the natural influence of the parent material. However, anthropogenic activities could also be responsible for REE enrichment in soil. To understand the effect of volcanic soil parent material (as a natural influence) and anthropogenic activities, we analyzed the enrichment and geoaccumulation factor of REE. The ecological risk index is used to obtain the potential REE contamination into ecosystem. The samples were taken from three Andisols soil profiles (Pangalengan, Lembang, and Wayangwindu) from the same quaternary volcanic rocks in West Java, Indonesia. REE content in Pangalengan soil varied from 0.25mgkg−1 (Tm) to 73.50mgkg−1 (Ce), Lembang soil ranged from 0.57mgkg−1 (Tm) to 77.30mgkg−1 (Ce), and Wayangwindu ranged from 0.17mgkg−1 (Tm) to 77.30mgkg−1 (Ce). The enrichment of REE in all Andisols soils from three different sites (Pangalengan, Lembang, Wayangwindu) was classified as a deficiency to minimal enrichment. The geoaccumulation of REE is classified as moderately contaminated that occurs only in A horizon in Pangalengan soil. The REE enrichment seems closely related to anthropogenic factors, especially in A horizon at Pangalengan. Parent materials weathering is the most dominant factor in REE enrichment in the subsurface horizon for all sites but in the surface horizon in Pangalengan related to agricultural activities. The ecological risk index of REE was smaller than 40 (low risk), except for Lu in Pangalengan soil at moderate risk.

Re-liquefaction characteristics of ground filled with volcanic ash soil

Re-liquefaction characteristics of ground filled with volcanic ash soil

Physical and mechanical characteristics of pyroclastic soil for the construction of embankments

In the framework of wider research activity on the physical and mechanical behaviour of volcanic soils, this paper reports the results of some laboratory tests on this type of geomaterial. The background of this research is the need for a construction company to possibly use pyroclastic material excavated along a tunnel profile to build railway embankments included in the design of a new High-Speed Train Line near the city of Naples, Italy. However, according to the standards of the National Italian Railways Company, pyroclastic soils cannot be employed as construction materials unless they are supported by a specific testing program demonstrating their good performance. The pyroclastic soil, which is widespread in the project area, is the product of Mt. Vesuvius volcanic activity. It is a coarse-graded soil that includes a significant percentage of non-plastic fines. They should be placed under compact conditions. The experimental campaign was aimed at identifying some physical characteristics that can synthesize the homogeneity of the pyroclastic deposit in terms of shearing resistance. The preliminary results obtained in terms of grading curves, modified Proctor compaction curves, and stress-strain curves from conventional drained triaxial tests are presented and discussed in this paper. The latter were executed on fully saturated specimens after compacting the soil at the optimum water content and on the dry and wet sides of the Proctor curve. The overall initial outcomes of the experimental campaign indicated that this material has acceptable characteristics and is suitable for the construction of railway embankments.

Durum Wheat Production and Soil Chemical Properties in Response to Three Biannual Rotation Cycles with Residue Incorporation

Crop rotations incorporating residues generates benefits in productivity and a better efficiency of resources. However, the incorporation of residues in high quantities is not a common practice, given the lack of comprehension of farmers of the effects on the following crop. This experiment was carried out in an Andisol soil in south-central of Chile. Three biannual rotation cycles (canola-durum wheat and bean-durum wheat) with four levels of residue incorporation (0%, 50%, 100% and 200%) were evaluated on the evolution of grain yield and production of durum wheat residues, and on chemical properties of the soil at the end of the three cycles. The results indicated that pre-cultivation affected the grain yield and residue production of durum wheat, highlighting the positive effect of the bean. In soil, a higher concentration of available N and exchangeable Ca, Mg and K was obtained in the bean-durum wheat rotation, and a higher concentration of available S in the canola- durum wheat rotation. By increasing the dose of waste, an increase in the concentrations of exchangeable Ca, Mg and K was achieved. Finally, the chemical properties of the soil presented positive and negative correlations associated with the management of liming, fertilization and nutrients mostly present in the incorporated waste. This study helped to validate that the continuous incorporation of the residues produced within the rotations in this volcanic soil contributes to the improvement of some of its chemical properties with no effect of yield of the durum wheat crop.