Basaltic Soils Research Articles

Optimizing ExoMars Rover Remote Sensing Multispectral Science: Cross‐Rover Comparison Using Laboratory and Orbital Data

AbstractMultispectral imaging instruments have been core payload components of Mars lander and rover missions for several decades. In order to place into context the future performance of the ExoMars Rosalind Franklin rover, we have carried out a detailed analysis of the spectral performance of three visible and near‐infrared (VNIR) multispectral instruments. We have determined the root mean square error (RMSE) between the expected multispectral sampling of the instruments and high‐resolution spectral reflectance data, using both laboratory spectral libraries and Mars orbital hyperspectral data. ExoMars Panoramic Camera (PanCam) and Mars2020 Perseverance Mastcam‐Z instruments have similar values of RMSE, and are consistently lower than for Mars Science Laboratory Mastcam, across both laboratory and orbital remote sensing data sets. The performance across mineral groups is similar across all instruments, with the lowest RMSE values for hematite, basalt, and basaltic soil. Minerals with broader, or absent, absorption features in these visible wavelengths, such as olivine, saponite, and vermiculite have overall larger RMSE values. Instrument RMSE as a function of filter wavelength and bandwidth suggests that spectral parameters that use shorter wavelengths are likely to perform better. Our simulations of the spectral performance of the PanCam instrument will allow the future use of targeted filter selection during ExoMars 2022 Rosalind Franklin operations on Mars.

Seed germination of Opuntia dejecta, a non-desert cactus native to Central America

Opuntia species from arid and semiarid environments have dormant seeds. The objective of this study was to evaluate how the soil influences seed germination of the cactus O. dejecta. We hypothesized that O. dejecta seeds in the basaltic rocky soil will show lower seed germination than seeds in a site with alluvial soil from the coastal plain. An experiment of partial reciprocal transplant was performed, placing seeds from basaltic soil (San Ignacio population) in pots containing alluvial soil from Puente Nacional population and in slabs from basaltic soil, and placing them on two greenhouses, in San Ignacio population and Puente Nacional population. We found that seed germination (%) was lower in San Ignacio site (with basaltic soil) than in Puente Nacional site (with alluvial soil), and that alluvial soil showed higher seed germination than basaltic soil, as well as higher seed germination in Puente Nacional than in San Ignacio. The results suggest that seed dormancy for the population situated in the rocky condition is a trait locally adapted, and the basaltic soil can be considered as a selection factor.

Complex burial histories of Apollo 12 basaltic soil grains derived from cosmogenic noble gases: Implications for local regolith evolution and future in situ investigations

AbstractWe report the concentrations and isotope ratios of light noble gases (He, Ne, Ar) in 10 small basalt fragments derived from lunar regolith soils at the Apollo 12 landing site. We use cosmic ray exposure (CRE) and shielding condition histories to consider their geological context. We have devised a method of using cosmogenic Ne isotopes to partition the CRE history of each sample into two stages: a duration of “deep” burial (shielding of 5–500 g cm−2) and a duration of near‐surface exposure (shielding of 0 g cm−2). Three samples show evidence of measurable exposure at the lunar surface (durations of between 6 ± 2 and 7 ± 2 Myr). The remaining seven samples show evidence of a surface residence duration of less than a few hundred thousand years prior to collection. One sample records a single‐stage CRE age range of between 516 ± 36 and 1139 ± 121 Myr, within 0–5 g cm−2 of the lunar surface. This is consistent with derivation from ballistic sedimentation (i.e., local regolith reworking) during the Copernicus crater formation impact at ~800 Myr. The remaining samples show CRE age clusters around 124 ± 11 Myr and 188 ± 15 Myr. We infer that local impacts, including Surveyor crater (180–240 Ma) and Head crater (144 Ma), may have brought these samples to depths where the cosmic ray flux was intense enough to produce measurable cosmogenic Ne isotopes. More recent small impacts that formed unnamed craters may have exhumed these samples from their deep shielding conditions to the surface (i.e., ~0–5 g cm−2) prior to collection from the lunar surface during the Apollo 12 mission.

Phytoprevention of Heavy Metal Contamination From Terrestrial Enhanced Weathering: Can Plants Save the Day?

Enhanced weathering is a promising approach to remove carbon dioxide from the atmosphere. However, it may also pose environmental risks through the release of heavy metals, in particular nickel and chromium. In this perspective article I explore the potential role of plants in modulating these heavy metal fluxes. Agricultural basaltic soils may be valuable study sites in this context. However, the effect of biomass harvesting on the accumulation of heavy metals is currently not well studied. Mostly caused by different parent rock concentrations, there is a large variability of heavy metal concentrations in basaltic and ultramafic soils. Hence, to minimize environmental risks of enhanced weathering, basalts with low heavy metal concentrations should be favored. Existing phytoremediation strategies may be used to “phytoprevent” the accumulation of nickel and chromium released from enhanced weathering in soils. As a result, elevated nickel and chromium concentrations in rocks must not preclude enhanced weathering in all settings. In particular, hyperaccumulating plants could be used as part of a crop rotation to periodically remove heavy metals from soils. Enhanced weathering could also be employed on fields or forests of (non-hyper) accumulating plants that have a high primary production of biomass. Both approaches may have additional synergies with phytomining or bioenergy carbon capture and storage, increasing the total amount of carbon dioxide drawdown and at the same time preventing heavy metal accumulation in soils.

Cooler Equatorial Climate in the Late Lopingian Estimated from Paleosols Developed on Emeishan Basalts

Paleosols that developed on large igneous province flood basalts provide a valuable opportunity to quantitatively reconstruct the terrestrial paleoclimate during a given period. This study uses a newly constructed basaltic soil–climate function to obtain terrestrial paleoclimatic data following the termination of the Emeishan basalt eruption in the late Lopingian (∼253 Ma). The constructed relationships are mean annual temperature of 32.81e−0.4166X (R2=0.55, standard error [SE]=4.6°C) and mean annual precipitation of −875.5ln(X)+1792 (R2=0.69, SE=328 mm), where X=SiO2/(Al2O3+Fe2O3) (the Saf index). We collected samples from nine paleosol profiles developed on the last-phase Emeishan basalts and conducted field observations as well as micromorphological, mineral composition, and geochemical analyses. On the basis of these paleosols, we reconstructed the regional mean temperature and precipitation to be 18.9°C±4.6°C and 1546±328 mm, respectively. The regional climate was cooler than those in modern equatorial regions of similar latitudes. The reduced CO2 concentration in the atmosphere resulting from rapid weathering of Emeishan basalts in a tropical climate could have played a dominant role in causing the regional cool terrestrial paleoclimate following the termination of the Emeishan basalt eruption.

Modelling soil organic carbon using vegetation indices across large catchments in eastern Australia

Soil organic carbon (SOC) is an important soil component. However, examining SOC at the large catchment scale is difficult due to the intensive labour requirements. This study examines SOC distribution at large (>500 km2) catchment scales using field-sampled SOC data and remote sensed vegetation indices located in eastern Australia (Krui River catchment - 562 km2; Merriwa River catchment – 808 km2) on grazing land-use basalt soil. The SOC data obtained was compared to digital elevation model (DEM) derived elevation and insolation data, as well as Normalised Difference Vegetation Index (NDVI) and the Enhanced Vegetation Index (EVI) values corresponding to each sample site. These indices were obtained from the MODIS sensor (Terra/Aqua) and Landsat series satellites. Vegetation Indices (VI) captured immediately prior to sampling demonstrated a poor correlation with SOC. The use of multiple, aggregated, prior VI data sets provided a good match with SOC. The strongest match occurred for Landsat 8 EVI, indicating that VIs with higher spatial and spectral resolution, which can account for atmospheric interference, have the potential to produce more accurate SOC mapping (Krui samples in 2006, R2 = 0.31, P < 0.01; Krui sampled in 2014, R2 = 0.41, P < 0.01; Merriwa samples in 2015, R2 = 0.37, P < 0.01). A sensitivity test for both remote sensing platforms demonstrated that the findings were robust. The results demonstrate that VIs are a reliable surrogate for historical vegetation growth in pasture dominated landscapes and therefore soil carbon inputs allowing for mapping of SOC across large catchment scales. Both Landsat and MODIS produced similar results and demonstrate that SOC can be reliably predicted at the large catchment scale and for different catchments in this environment with RMSE range of 0.79 to 1.06. The method and data can be applied globally and provides a new method for environmental assessment.

Comparison of Frequentist and Bayesian Generalized Linear Models for Analyzing the Effects of Fungicide Treatments on the Growth and Mortality of Piper Nigrum

Foot rot disease poses a devastating threat to pepper agriculture. In Vietnam, conventionally, fungicides are the control methods used against the disease. However, the practical effectiveness of fungicide treatment has yet to be quantitatively assessed. To fill this gap a three-factorial experiment was conducted, the factors of which were fungicide application, soil type, and infection pathway, with plant mortality and plant growth as the target variables. Two of the most common fungicides were chosen, including Agrifos 400 (potassium phosphonate) and Aliette 800WG (fosetyl-Al). The two fungicides were used in multiple treatment plans, with soil drenching selected as the means of controlling foot rot disease on red basalt soil and red basalt soil added with organic matter in a greenhouse experiment. Three-month-old pepper (Piper nigrum) plants were treated with Agrifos (application interval of 10 and 20 days), Aliette (application interval of 30 and 60 days), and a combination of both fungicides at half doses. Pepper plants were infected with the fungus Pythium spp. from soil or by direct inoculation. To assess the effect of fungicides on foot rot mortality and the growth of pepper plants, multiple generalized linear models were set up using frequentist and Bayesian approaches. Generally, both procedures suggest the same conclusions for model selection in terms of the Akaike information criterion (AIC) and the deviance information criterion (DIC). Fungicide type was found to be the main factor that affected the survival of plants. Most of the treatments (except Aliette, with an interval of 60 days) effectively reduced the mortality. The usage of fungicides affected the growth of plants in interaction with soil types. Aliette suppressed the growth of plants, especially on red soil, while Agrifos had no effect on the growth of pepper plants. The combined application of Agrifos and Aliette with half doses proves to be a promising solution for balancing cost and effectiveness in protecting plants against foot rot pathogens without affecting their growth. In our case, under the inhomogeneity of variance and unbalanced samples, the Bayesian inference appeared to be the most useful because of its flexibility in terms of model structure.

Alteration of high alkaline and alkaline basaltic rocks: parent rocks in the Lava Durian orchard, Sisaket Province, NE Thailand

Lava Durian Sisaket is the first geographically identified (GI) fruit related to the volcano in Thailand and distributed in three districts of Sisaket Province, the southernmost edge of the Khorat Plateau. The parent rocks of orchards are important for the description of soil and rock relation with respect to mineralogical and geochemical characteristics. This work aims to study lithology, mineralogy, and geochemistry of basaltic rocks, parent rocks of in situ soil in these orchards, and delineate the existing basaltic soil models. The several orchards are covered by reddish-brown to brown in situ soils, weathered from mafic volcanic rocks: porphyritic olivine basalt, vesicular olivine basalt, and nephelinite. The microscopic image analysis, XRD, and MiniSEM-EDS are used to classify mineralogy, while XRF and analysis of large and rare elements in ICP-MS/ICP-OES were used to determine parental rocks geochemistry and alteration. The olivine basalts comprise forsterite microphenocrysts associated with bytownite, diopside, augite, pigeonite, and ilmenite groundmass, while nephelinite is composed of nepheline groundmass and bytownite-labradorite, diopside, augite, pigeonite, and ilmenite crystals. In addition, these basalts display high alteration rates, especially olivine highly altered to iddingsite. According to the geochemical data, Sisaket's basalts were identified as alkali basalt and nepheline basanite with high LILEs and LREEs (La, Nd, Pr, Gd, Eu). The kaolinite, smectite, and illite are altered from felsic minerals, while the chlorite and iddingsite are from mafic minerals. The mineralogical analyses classified secondary phyllosilicates related to low-moderate temperature hydrothermal fluid, very high cation exchange capacity (H+, K+, Ca2+, Mg2+), and tropical weathering. The alkaline and high alkaline basalts, presenting as parent rocks, are one of the parameters that produced good nitisal soil of Sisaket's agricultural areas.

Contrasting Community Assembly Forces Drive Microbial Structural and Potential Functional Responses to Precipitation in an Incipient Soil System.

Microbial communities in incipient soil systems serve as the only biotic force shaping landscape evolution. However, the underlying ecological forces shaping microbial community structure and function are inadequately understood. We used amplicon sequencing to determine microbial taxonomic assembly and metagenome sequencing to evaluate microbial functional assembly in incipient basaltic soil subjected to precipitation. Community composition was stratified with soil depth in the pre-precipitation samples, with surficial communities maintaining their distinct structure and diversity after precipitation, while the deeper soil samples appeared to become more uniform. The structural community assembly remained deterministic in pre- and post-precipitation periods, with homogenous selection being dominant. Metagenome analysis revealed that carbon and nitrogen functional potential was assembled stochastically. Sub-populations putatively involved in the nitrogen cycle and carbon fixation experienced counteracting assembly pressures at the deepest depths, suggesting the communities may functionally assemble to respond to short-term environmental fluctuations and impact the landscape-scale response to perturbations. We propose that contrasting assembly forces impact microbial structure and potential function in an incipient landscape; in situ landscape characteristics (here homogenous parent material) drive community structure assembly, while short-term environmental fluctuations (here precipitation) shape environmental variations that are random in the soil depth profile and drive stochastic sub-population functional dynamics.

Preferential removal of benzene, toluene, ethylbenzene, and xylene (BTEX) by persulfate in ethanol-containing aquifer materials.

The effective approaches to eliminate impacts of ethanol on the biodegradation of benzene, toluene, ethylbenzene, and xylene (BTEX) are concerned in the bioremediation of groundwater contaminated with ethanol-blended gasoline. In situ chemical oxidation (ISCO) is a common technique widely used for the remediation of contaminated groundwater. However, the selectivity of ISCO for BTEX and ethanol removal is poorly understood. Therefore, a batch experiment was performed with different aquifer materials, including calcareous soil, basalt soil, granite soil, dolomite, and sand. Gasoline was used to provide dissolved BTEX and ethanol reagent was used as additive to improve the quality of gasoline and to reduce the possibility of air pollution caused by gasoline. Persulfate (PS) was used as a chemical oxidant to oxidize organic contaminants. The target concentrations of BTEX and ethanol were 20mg/L and 1000mg/L, respectively. The results showed that ethanol could be preferentially degraded in the absence of PS and inhibit BTEX biodegradation. However, BTEX could be preferentially removed prior to ethanol in all aquifer materials used at ambient temperature, when PS was added at a PS/BTEX molar ratio of 150. Over 94% BTEX in sand, dolomite, and granite soil was preferentially removed with the first-order decay rate constants of 0.890-2.703day-1 within the first ~ 10days, followed by calcareous and basalt soil at the constants of 0.123-0.371day-1. Ethanol could compete with BTEX for sulfate radical at the first-order decay rate constants of 0.005-0.060day-1 for the first 25days, which was slower than that of BTEX. The pH quickly decreased to < 2.5 in dolomite, sand, and granite soil, but maintained > 6.2 in calcareous soil. Rich organic matter in calcareous and basalt soil had an inhibition effect on BTEX oxidation by PS. The pH buffer in calcareous soil may imply the potential of PS oxidation combined with bioremediation in carbonate rock regions.

Multi-Omics Analysis Reveals the Mechanism Underlying the Edaphic Adaptation in Wild Barley at Evolution Slope (Tabigha).

At the microsite “Evolution Slope”, Tabigha, Israel, wild barley (Hordeum spontaneum) populations adapted to dry Terra Rossa soil, and its derivative abutting wild barley population adapted to moist and fungi‐rich Basalt soil. However, the mechanisms underlying the edaphic adaptation remain elusive. Accordingly, whole genome bisulfite sequencing, RNA‐sequencing, and metabolome analysis are performed on ten wild barley accessions inhabiting Terra Rossa and Basalt soil. A total of 121 433 differentially methylated regions (DMRs) and 10 478 DMR‐genes are identified between the two wild barley populations. DMR‐genes in CG context (CG‐DMR‐genes) are enriched in the pathways related with the fundamental processes, and DMR‐genes in CHH context (CHH‐DMR‐genes) are mainly associated with defense response. Transcriptome and metabolome analysis reveal that the primary and secondary metabolisms are more active in Terra Rossa and Basalt wild barley populations, respectively. Multi‐omics analysis indicate that sugar metabolism facilitates the adaptation of wild barley to dry Terra Rossa soil, whereas the enhancement of phenylpropanoid/phenolamide biosynthesis is beneficial for wild barley to inhabit moist and fungi pathogen‐rich Basalt soil. The current results make a deep insight into edaphic adaptation of wild barley and provide elite genetic and epigenetic resources for developing barley with high abiotic stress tolerance.

Potential CO2 removal from enhanced weathering by ecosystem responses to powdered rock

Negative emission technologies underpin socioeconomic scenarios consistent with the Paris Agreement. Afforestation and bioenergy coupled with carbon dioxide (CO2) capture and storage are the main land negative emission technologies proposed, but the range of nature-based solutions is wider. Here we explore soil amendment with powdered basalt in natural ecosystems. Basalt is an abundant rock resource, which reacts with CO2 and removes it from the atmosphere. Besides, basalt improves soil fertility and thereby potentially enhances ecosystem carbon storage, rendering a global CO2 removal of basalt substantially larger than previously suggested. As this is a fully developed technology that can be co-deployed in existing land systems, it is suited for rapid upscaling. Achieving sufficiently high net CO2 removal will require upscaling of basalt mining, deploying systems in remote areas with a low carbon footprint and using energy from low-carbon sources. We argue that basalt soil amendment should be considered a prominent option when assessing land management options for mitigating climate change, but yet unknown side-effects, as well as limited data on field-scale deployment, need to be addressed first.

Impacts of residue quality and soil texture on soil aggregation pathways by using rare earth oxides as tracers

Rare earth oxides (REOs) as tracers track aggregate formation and breakdown pathways. However, investigations on the impacts of residue quality and soil texture on aggregation pathways are lacking. In this study, easily, moderately and slowly decomposable residues with different qualities (milk vetch, C/N = 16.7; maize, C/N = 35.5; and decomposed maize, C/N = 30.8) were applied to four types of red soils (Red clay, Basalt, Sandstone and Granite) with a range of soil textures. Aggregate fractions of each soil were labelled by different REOs. The soil respiration (CO2), mean weight diameter (MWD) and REOs concentrations were measured after 0, 7, 14, 28 and 56 days of incubation. The results showed that except for Basalt soil, the incorporation of organic residues increased the formation but decreased the breakdown of macroaggregates in the order of milk vetch > maize > decomposed maize in the first two weeks, thus leading to a greater standardized MWD in higher-quality residue-incorporated soils. In the mid-to-late incubation time (28–56 d), the standardized MWD and relative formation of macroaggregates in the milk vetch and maize treatments converged regardless of soil types. An exponential relation between the standardized MWD and accumulated CO2 (P < 0.05) indicated that the residue quality-dependent MWD dynamics were further driven by microbial activity. The two coarse-textured soils (Sandstone and Granite) presented a more rapid response of aggregation to microbial activity than the two fine-textured soils (Red clay and Basalt) did. The relative formation of 2–5 mm aggregates was significantly greater in Sandstone soil at a given residue incorporation, thus leading to a faster increase in the standardized MWD compared with fine-textured soils. However, a similar result was not observed in Granite soil. A positive linear relationship between the standardized MWD and 2–5 mm aggregate formation in all investigated soils (P < 0.001) suggested that MWD dynamics mainly depended on the newly formed large macroaggregate rate. Our study demonstrates that the dynamics of soil aggregation are closely related to microbial activity and newly formed macroaggregates, beyond the impacts of residue quality and soil texture on soil aggregation.

The distribution and presence of versicular-arbuscular mycorrhiza fungi in rhizosphere soil of Da Xanh pummelo in Ba Ria Vung Tau province

The study was carried out to determine the distribution and presence of versicular-arbuscular mycorrhiza (VAM) fungi in rhizosphere soil and roots of Da Xanh pummelo in Phu My town, Ba Ria Vung Tau province. The rhizosphere soil and root samples were collected from 6 - 7 years old pummelo of two main soil types, on two soil layers at depths of 0 - 20 cm and 20 - 40 cm, at 2/3 and the edge of canopy. The results showed that the presence of VAM spore density was higher in red basaltic soil (ferralsols) than black soil (luvisols), and common exist on the topsoil layer (0 - 20 cm) as well as the edge of canopy. Glomus and Acaulospora were two most abundant genera in survey areas, and the proportion of mycorrhizal spores ranged from 53.18 ± 2.59% to 58.54 ± 0.46 and from 23.68 ± 2.96% to 29.33 ± 0.64%, respectively. Increasing the soil depth negatively affected on spore density of VAM fungi. The VAM fungi composition aslo changed with soil depth. The percentage of root colonization by VAM fungi ranged from 56.20 ± 3.11% to 62.00 ± 3.37%, and the highest percentage of root colonization by VAM fungi was detected in red basaltic soil.

Heterogeneity in African savanna elephant distributions and their impacts on trees in Kruger National Park, South Africa.

Though elephants are a major cause of savanna tree mortality and threaten vulnerable tree species, managing their impact remains difficult, in part because relatively little is known about how elephant impacts are distributed throughout space.This is exacerbated by uncertainty about what determines the distribution of elephants themselves, as well as whether the distribution of elephants is even informative for understanding the distribution of their impacts.To better understand the factors that underlie elephant impacts, we modeled elephant distributions and their damage to trees with respect to soil properties, water availability, and vegetation in Kruger National Park, South Africa, using structural equation modeling.We found that bull elephants and mixed herds differed markedly in their distributions, with bull elephants concentrating in sparsely treed basaltic sites close to artificial waterholes and mixed herds aggregating around permanent rivers, particularly in areas with little grass.Surprisingly, we also found that the distribution of elephant impacts, while highly heterogeneous, was largely unrelated to the distribution of elephants themselves, with damage concentrated instead in densely treed areas and particularly on basaltic soils.Results underscore the importance of surface water for elephants but suggest that elephant water dependence operates together with other landscape factors, particularly vegetation community composition and historical management interventions, to influence elephant distributions.

Weathering sequence of soils along a basalt-sandstone toposequence in the Brazilian Cerrado

Despite a multitude of studies on fertility and physics of tropical soils, the effect of soil parent material on their genesis, chemical and mineralogical composition is not yet fully understood. Here, we studied a toposequence of four deep, well-developed soils along a basalt-sandstone transition, comprising two Ferralsols and one Luvisol on the summit and midslopes of a basalt plateau, and one Cambisol at a lower sandstone plateau. Basalt soils had high (42–77%) clay contents, and were mostly comprised by gibbsite, Fe oxides, and poorly crystalline kaolinite, whereas the sandstone soil had < 20% clay and kaolinitic clay. The studied Ferralsols were moderately to highly fertile, presented pH values 6.4–7.2 and blocky instead of the common granular structure, contrasting with most gibbsitic Ferralsols in tropical Brazil. The Luvisol showed very high base nutrient contents but lower pH (5.5–6.0), and the sandy Cambisol was also relatively fertile. All soils had no exchangeable Al3+, which was also unusual for Cerrado soils, which are mostly very acidic and nutrient-poor. Most likely these unusual features result from the formation of an interstratified clay mineral complex between kaolinite and mica, which occurred as a major phase in the Luvisol and as traces in Ferralsols. Micromorphological analysis showed that celadonite, a green-colored inclusion probably comprised by muscovite/paragonite micas, was a major component of the basalt and the last mineral to weather within the Luvisol. Thus, the toposequence ranged from the less developed, high-activity clay Luvisol to extremely weathered, gibbsitic Ferralsols, with the sandstone Cambisol in an intermediate stage of development.

Deficiency of essential elements in volcanic soils: potential harmful health effects on grazing cattle.

Several essential nutrients such as Fe, Co, Cu, I, Se, and Zn are vital to grazing cattle as they play a significant role in intracellular enzyme systems, with antioxidant and repair functions of DNA lesions. Feeds may supply most essential nutrients in adequate amounts. However, essential nutrient deficiencies are common and are mainly related to the geochemical characteristics of the soils, inherited from parent rocks. This study aims to assess the concentrations of the selected essential nutrients in topsoils and pasture grass from São Miguel Island (Azores) and discuss the possible effects of its deficiency in grazing cattle health. Sixty-eight samples of agricultural (pastures) topsoil and thirty samples of pasture grass were collected throughout São Miguel Island in areas with basaltic and trachytic parent rocks. Soil physicochemical properties and geochemical baselines of selected elements were determined on composite samples of soil and pasture grass in each site. Results indicate that the highest concentrations of the selected essential nutrients were observed in areas with basaltic soils, while the lowest values were found in areas with trachytic soils. These differences are considered of geogenic origin since they result from the weathering of volcanic parent rocks with different geochemical compositions. Data indicate a lack of some essential nutrients in topsoils (Co and Se) and/or pasture grass (Co, Cu, Se, and Zn) that can contribute to harmful health effects on grazing cattle. The uneven distribution of essential nutrients in topsoil and pasture grass and their deficiency can lead to several health problems in the cattle since these elements regulate physiological functions in biological systems. The identification of these deficit sites is important as it can help farmers to implement soil and/or animal supplementation programs to diminish possible health problems.

Suscetibilidade magnética na caracterização da variabilidade espacial de atributos do solo em solos subtropicais

Magnetic susceptibility (MS) has been used to estimate soil attributes. With the proposal to increase the information of soils in southern Brazil the objectives of this work were: (i) evaluate the correlation of SM with soil attributes in a slope of subtropical basaltic soils; (ii) to characterize the spatial variation structure of MS and the content of sand, clay and COS; and (iii) identify the sample density that captures the spatial variability to assist future work under similar conditions. In a 22 ha area located in Santo Augusto - RS, Brazil, an 87 points sample grid was collected to determine soil attributes. Samples were also collected in five profiles along the slope. The profile data were analyzed by correlation to verify the degree of Pearson correlation of the SM with the attributes of the soil. In the sample grid spatial dependence analyzes were performed to assess the degree of spatial dependence on soil attributes. The MS presented a high correlation with the attributes of clay soil, Fes, Fed and COS. The evaluation of the spatial variation structure showed that the attributes presented a degree of spatial dependence ranging from weak for COS to strong for MS. The spatial variability pattern suggests a sample density of one point every 4 to 12 ha.

Quantification of water stress impacts on canopy traits, yield, quality and water productivity of onion (Allium cepa L.) cultivars in a shallow basaltic soil of water scarce zone

Understanding and mitigating the adverse impacts of water stress on agriculture production have become global concern in water scarce environments. Particularly, Deccan plateau, the largest semi-arid zone of peninsular India, is confronted with severe water resources conflicts and extensive pressure for food production under climate change scenario. For sustainable agriculture, it is critical to quantify the impact of water stress on major crops like winter onion (Allium cepa L.) which is grown under diverse water management practices on shallow basaltic soils of this region. We conducted a field experiment during two growing seasons (2017–18 and 2018–19) for evaluating responses of different cultivars of red (B. Raj, B. Kiran, B. Super, B. Red and Local-Fursangi) and white (B. Shubra, B. Sweta and B. Safed) onion to variable water stress created using a line source sprinkler (LSS) system. There was a 1.1, 1.6, 3.9, 9.2 fold decline in total bulb yields (TBY) with increasing water deficit i.e. when depth of irrigation water (IW) applied equalled 0.60, 0.40, 0.20 and 0.00 times the cumulative open pan evaporation (CPE) as compared with the recommended practice (IW:CPE 0.80). The TBY increased between 86.2 and 106.6 Mg ha−1 in red cultivars when irrigation was scheduled at excess to optimum water regimes (IW: CPE 0.80–1.00), while it was improved by 5.0–20.4% for white cultivars under medium (0.40–0.59) to severe (0.0–0.39) water deficit stress. Further, highest (4.3–16.2%) improvement in TBY of Local cultivar was reported irrespective to different water stress levels. Local and white cultivars could have better tolerance to water stress by keeping cooler canopy temperatures, higher leaf relative water content and modulating the stomatal opening. Lower yield losses due to rotting (0.30–1.81%) and splitting (4.4–6.5%) of bulbs were observed in red and white cultivars. This study further endorses the appropriate selection of onion cultivars reduces water requirements by 37.5–61% to attain similar water productivity (16.0 kg m−3) as with recommended irrigation level. Increased in water stress levels though reduced quality of physical traits of harvested bulbs viz., mean weight, average dia., shape index (SI), harvest index (HI) and firmness, these improved the storage quality. Water deficit also increased accumulation of soluble solids, total phenolics, protein, dry matter and elevated the pH and rehydration quality besides potentially affecting the enzymatic activity (SOD and POD) of onion cultivars. It was concluded that white onion cultivars like B. Shubra with higher WP under medium and severe water deficit stress and ‘Local’ red cultivar should be preferred for efficient utilisation of water resources both in terms of the productivity and post-harvest quality of onion under drought prone and shallow basaltic regions of Deccan plateau.

TEORES DE VANÁDIO, MOLIBDÊNIO E ANTIMÔNIO EM SOLOS DE DIFERENTES LITOLOGIAS EM SANTA CATARINA

VANADIUM, MOLYBDENUM AND ANTIMONY CONTENTS IN SOILS OF DIFFERENT LITHOLOGIES IN SANTA CATARINA. Trace element levels knowledge in soils is important for establishing quality standards. This study has objective to determine levels of vanadium (V), molybdenum (Mo) and antimony (Sb) in soils from Santa Catarina, observing the different source materials and establishing relationships between these elements and soil properties. The extractions occurred according to USEPA 3051 A protocol, with nitric and hydrochloric acid addition for V and Mo and only with hydrochloric acid for Sb. The quantification of V and Mo occurred by inductively coupled plasma optical emission spectrometry and of Sb by hydride generation inductively coupled plasma optical emission spectrometry. The results were submitted to variance analysis and Scott-Knott test and evaluated by Pearson’s correlation with soil attributes. V and Mo contents differed between soils of different source materials. Highest V levels were found in andesite and basalt soils and Mo in porphyry phonolite, granite, mica schist and sedimentary rocks. V and Sb showed a positive correlation with each other and with oxides of iron, silt, and organic carbon. Mo showed a negative correlation with cation exchange capacity (CEC), iron oxides and organic carbon