cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.14278287
title: Yeast species and strains differing along an altitudinal gradient in the Brazilian forest domain

description: ABSTRACT Soil microbiota is an important component of the forest biomes, playing important roles in the soil aggregation and cycling of nutrients. Among the soil microorganisms stand out the yeasts, which are unicellular fungi involved in important soil ecological processes. The Brazilian Atlantic Forest is one of the main biodiversity hotspots in the world, and the effect of altitudinal gradient on the distribution patterns of yeast species across this ecosystem has not yet been addressed. Thus, this study aimed to investigate the occurrence and distribution of yeast species in soils along an altitude gradient (404; 1,016; 1,658; and 2,124 m above the sea level) of Serra dos Órgãos National Park located at Rio de Janeiro State, Brazil. Yeast species were described using a culture-based method. Species identification was performed using the fungal barcode locus, the D1/D2 region of 26S rRNA, and the gene genealogy was used to access the intraspecific distribution of strains along the altitudinal gradient. We isolated and identified a total of 76 yeasts including ten species belonging to eight genera. Basidiomycetes predominated over ascomycetes. Saitozyma podzolica and Meyerozyma guilliermondii were isolated at all altitudes. The principal component analysis showed that 88 % of sample distribution is explained by soil properties. For S. podzolica, the genetic genealogy suggested that intraspecific distribution is likely related to similar altitudes. Overall, the species composition and soil properties were modified as altitude was increasing, being more heterogeneous and richness in high altitudes.
DOI: 10.6084/m9.figshare.14278287.v1
title: Yeast species and strains differing along an altitudinal gradient in the Brazilian forest domain

description: ABSTRACT Soil microbiota is an important component of the forest biomes, playing important roles in the soil aggregation and cycling of nutrients. Among the soil microorganisms stand out the yeasts, which are unicellular fungi involved in important soil ecological processes. The Brazilian Atlantic Forest is one of the main biodiversity hotspots in the world, and the effect of altitudinal gradient on the distribution patterns of yeast species across this ecosystem has not yet been addressed. Thus, this study aimed to investigate the occurrence and distribution of yeast species in soils along an altitude gradient (404; 1,016; 1,658; and 2,124 m above the sea level) of Serra dos Órgãos National Park located at Rio de Janeiro State, Brazil. Yeast species were described using a culture-based method. Species identification was performed using the fungal barcode locus, the D1/D2 region of 26S rRNA, and the gene genealogy was used to access the intraspecific distribution of strains along the altitudinal gradient. We isolated and identified a total of 76 yeasts including ten species belonging to eight genera. Basidiomycetes predominated over ascomycetes. Saitozyma podzolica and Meyerozyma guilliermondii were isolated at all altitudes. The principal component analysis showed that 88 % of sample distribution is explained by soil properties. For S. podzolica, the genetic genealogy suggested that intraspecific distribution is likely related to similar altitudes. Overall, the species composition and soil properties were modified as altitude was increasing, being more heterogeneous and richness in high altitudes.
DOI: 10.6084/m9.figshare.14278290
title: Comparison of water and osmotic potentials on Vigna unguiculata stress response

description: ABSTRACT Drought and soil salinity are the main abiotic stresses in semiarid regions of the world. This study aims to evaluate the effect of water tensions generated by the reduction of soil moisture and salt on the leaf water potential of cowpea (Vigna unguiculata L. Walp). The experiments were conducted in a randomized complete block design, with a 6 × 2 factorial arrangement consisted of six soil water tensions (0.025, 0.265, 0.485, 0.705, 0.925, and 1.145 MPa) and two tension sources (water deficit and salt), with four replications. Two experiments were performed with the same environmental conditions to evaluate the influence of the tensions on vegetative and reproductive stages. Water and osmotic potentials, relative water content, leaf succulence, and shoot biomass yield were evaluated. Soil water tension was not the main factor of changes on water and osmotic potentials of V. unguiculata plants; the water deficit treatments at soil water tensions of up to 1.145 MPa did not reduce the water and osmotic potentials either at the vegetative or flowering phenological stages; high correlations were found between shoot biomass yield and the leaf water potential at seven days after stress. The osmotic potential was the main indicator of stress in plants at the vegetative and flowering stages subjected to water deficit by the presence of salts in the soil solution.
DOI: 10.6084/m9.figshare.14278290.v1
title: Comparison of water and osmotic potentials on Vigna unguiculata stress response

description: ABSTRACT Drought and soil salinity are the main abiotic stresses in semiarid regions of the world. This study aims to evaluate the effect of water tensions generated by the reduction of soil moisture and salt on the leaf water potential of cowpea (Vigna unguiculata L. Walp). The experiments were conducted in a randomized complete block design, with a 6 × 2 factorial arrangement consisted of six soil water tensions (0.025, 0.265, 0.485, 0.705, 0.925, and 1.145 MPa) and two tension sources (water deficit and salt), with four replications. Two experiments were performed with the same environmental conditions to evaluate the influence of the tensions on vegetative and reproductive stages. Water and osmotic potentials, relative water content, leaf succulence, and shoot biomass yield were evaluated. Soil water tension was not the main factor of changes on water and osmotic potentials of V. unguiculata plants; the water deficit treatments at soil water tensions of up to 1.145 MPa did not reduce the water and osmotic potentials either at the vegetative or flowering phenological stages; high correlations were found between shoot biomass yield and the leaf water potential at seven days after stress. The osmotic potential was the main indicator of stress in plants at the vegetative and flowering stages subjected to water deficit by the presence of salts in the soil solution.
DOI: 10.6084/m9.figshare.14278292
title: Total fungi and yeast distribution in soils over native and modified vegetation in central Brazil

description: ABSTRACT Fungi are ubiquitous components of soil microbial communities, generally comprise the largest proportion of soil biomass. They can occur as filamentous forms or unicellular yeasts, in both, as free-living or symbionts. Next generation sequencing has allowed greater depth of the access to soil fungal diversity complementing culture-dependent results. In Brazil, the state of Minas Gerais is recognized for its mining activity, which modifies the vegetation cover and consequently the soil microbial communities. To describe the fungal community (total fungi and yeast) in a post-mining area, comparing natural and modified ecosystems, we used environmental metabarcoding of ITS2 region. We assessed four ecosystems, with different vegetation and levels of impact, ranging from none to high impact (Atlantic forest, Iron outcrops, Eucalyptus, and Grass). Sequence data were compared with culture data obtained from previous studies. The fungal communities (total fungi and yeast) were more similar between Eucalyptus and Atlantic Forest, while Grass and Iron outcrops ecosystems showed greater dissimilarity. Despite its modified state, Grass ecosystem presented the highest alpha diversity values. Yeasts represented a proportion of fungal communities ranging from 1.7 to 17 % of fungal sequences in soil. The Ascomycota:Basidiomycota ratio was higher for the total fungi analysis, while a greater proportion of Basidiomycota was observed with the yeast analysis. Grass ecosystem was the only exception, where a higher proportion of ascomycetous yeasts was detected. The yeast communities responded to the environmental stress caused by the mining activity, resulting in changes in the composition, mainly increasing the abundance of black yeasts. Saitozyma podzolica relative abundance obtained with ITS sequencing was coherent with the findings obtained with culture data. Despite greater diversity depth obtained by metabarcoding, sequence and culture data were complementary tools in describing the fungal soil community. This study contributes significantly to the inventory of yeast species in tropical and subtropical soils.
DOI: 10.6084/m9.figshare.14278292.v1
title: Total fungi and yeast distribution in soils over native and modified vegetation in central Brazil

description: ABSTRACT Fungi are ubiquitous components of soil microbial communities, generally comprise the largest proportion of soil biomass. They can occur as filamentous forms or unicellular yeasts, in both, as free-living or symbionts. Next generation sequencing has allowed greater depth of the access to soil fungal diversity complementing culture-dependent results. In Brazil, the state of Minas Gerais is recognized for its mining activity, which modifies the vegetation cover and consequently the soil microbial communities. To describe the fungal community (total fungi and yeast) in a post-mining area, comparing natural and modified ecosystems, we used environmental metabarcoding of ITS2 region. We assessed four ecosystems, with different vegetation and levels of impact, ranging from none to high impact (Atlantic forest, Iron outcrops, Eucalyptus, and Grass). Sequence data were compared with culture data obtained from previous studies. The fungal communities (total fungi and yeast) were more similar between Eucalyptus and Atlantic Forest, while Grass and Iron outcrops ecosystems showed greater dissimilarity. Despite its modified state, Grass ecosystem presented the highest alpha diversity values. Yeasts represented a proportion of fungal communities ranging from 1.7 to 17 % of fungal sequences in soil. The Ascomycota:Basidiomycota ratio was higher for the total fungi analysis, while a greater proportion of Basidiomycota was observed with the yeast analysis. Grass ecosystem was the only exception, where a higher proportion of ascomycetous yeasts was detected. The yeast communities responded to the environmental stress caused by the mining activity, resulting in changes in the composition, mainly increasing the abundance of black yeasts. Saitozyma podzolica relative abundance obtained with ITS sequencing was coherent with the findings obtained with culture data. Despite greater diversity depth obtained by metabarcoding, sequence and culture data were complementary tools in describing the fungal soil community. This study contributes significantly to the inventory of yeast species in tropical and subtropical soils.
DOI: 10.6084/m9.figshare.14278293
title: Winter cover crops effects on soil organic carbon and soil physical quality in a Typical Argiudoll under continuous soybean cropping

description: ABSTRACT The massive adoption of no-tillage (NT), along with the simplification of the cropping sequences has led to physical and chemical degradation of soils. To recover degraded soils, cover crops have been proposed as an alternative to increase soil organic carbon (SOC) and to improve soil physical quality (SPQ). This study aimed (i) to determine the content of SOC and its physical and chemical fractions at different layers and positions, in a soil with a soybean crop under NT with and without winter cover crops, and (ii) to determine SPQ indicators in a soybean crop under NT with and without winter cover crops. Measures and samples were made on a field experiment in a typical Argiudoll of the Argentinean Pampas. Soil organic carbon, coarse and fine particulate organic carbon (POCc and POCf), mineral associated organic carbon (MOC), fulvic acids (FA), humic acids (HA), and humins (H) were determined. Soil physical quality indicators determined were: soil bulk density and total porosity from field samples, and saturated hydraulic conductivity, water-conducting macro and mesoporosity, and total porosity connectivity from field water infiltration data. After eight years, cover crops did not cause any observable change in whole SOC content, but significant differences were observed for some SOC fractions. Humic acids and POCc had 40 and 25 % increases, respectively, in the cover crop treatment. Mineral associated organic carbon and H decreased by 9 and 7 % in cover crop treatment. Soil physical quality did not improve after eight years of cover crops. This can be related to degradation processes after 20 years of soybean monoculture under NT, and to the low ability of Argiudolls to recover from physical degradation.
DOI: 10.6084/m9.figshare.14278293.v1
title: Winter cover crops effects on soil organic carbon and soil physical quality in a Typical Argiudoll under continuous soybean cropping

description: ABSTRACT The massive adoption of no-tillage (NT), along with the simplification of the cropping sequences has led to physical and chemical degradation of soils. To recover degraded soils, cover crops have been proposed as an alternative to increase soil organic carbon (SOC) and to improve soil physical quality (SPQ). This study aimed (i) to determine the content of SOC and its physical and chemical fractions at different layers and positions, in a soil with a soybean crop under NT with and without winter cover crops, and (ii) to determine SPQ indicators in a soybean crop under NT with and without winter cover crops. Measures and samples were made on a field experiment in a typical Argiudoll of the Argentinean Pampas. Soil organic carbon, coarse and fine particulate organic carbon (POCc and POCf), mineral associated organic carbon (MOC), fulvic acids (FA), humic acids (HA), and humins (H) were determined. Soil physical quality indicators determined were: soil bulk density and total porosity from field samples, and saturated hydraulic conductivity, water-conducting macro and mesoporosity, and total porosity connectivity from field water infiltration data. After eight years, cover crops did not cause any observable change in whole SOC content, but significant differences were observed for some SOC fractions. Humic acids and POCc had 40 and 25 % increases, respectively, in the cover crop treatment. Mineral associated organic carbon and H decreased by 9 and 7 % in cover crop treatment. Soil physical quality did not improve after eight years of cover crops. This can be related to degradation processes after 20 years of soybean monoculture under NT, and to the low ability of Argiudolls to recover from physical degradation.
DOI: 10.6084/m9.figshare.14278299
title: Nitrous oxide emissions from a tropical Oxisol under monocultures and an integrated system in the Southern Amazon – Brazil

description: ABSTRACT Although agriculture and livestock systems represent important sources of N2O from the soil, they may also aid in emissions mitigation, mainly when integrated systems are taken into account, such as crop-livestock-forest, for food production. This work assessed the soil N2O emissions from a tropical Oxisol under row-crop, livestock, forest monocultures, and an integrated crop-livestock-forest system in the Southern Amazon - Brazil. Soil N2O emissions were measured using static chambers from November 2014 to October 2016 in four soil use systems [row-crop, livestock, forest, and integrated crop-livestock-forest (CLF)], and in a reference area under native forest fragment. For the whole period, the average of soil N2O fluxes was 16.9, 12.2, and 15.4 µg N2O-N m-2 h-1, to row-crop, livestock, and CLF systems, respectively, all with a similar average among them. The lowest fluxes were observed in the forest system and native forest fragment, with average fluxes of 4.0 and 6.3 µg N2O-N m-2 h-1, respectively, both lower than the agricultural systems. The largest soil N2O fluxes were observed throughout the rainy seasons in the row-crop, livestock, and CLF, mostly after N-fertilizer application to the soil surface or in the planted row. As a consequence, the cumulative emissions were greater in row-crop, livestock, and CLF systems, which in the averages of two cycles emitted respectively 1.40, 1.15, and 1.27 kg N2O-N ha-1 yr-1, all different of the forest system and native forest fragment (0.33 and 0.52 kg N2O-N ha-1 yr-1, respectively). Nitrogen fertilization and soil moisture influenced soil N2O emissions of all systems assessed in the Southern Amazon. The N2O emissions took place after both factors were met, corroborating the hole-in-the-pipe model. Even with more soil use intensification, once in the same area there were three cultures in succession during a year and perennial trees, CLF did not lead to greater N2O emissions from the soil than row-crop and livestock. Thus, CLF represents a good option for N2O mitigation for the edaphic and climatic conditions of the Southern Amazon.
DOI: 10.6084/m9.figshare.14278296
title: Physical properties of a Brazilian sandy loam soil after the traffic of a military vehicle M113 BR

description: ABSTRACT Soil physical properties can be changed after vehicle traffic, especially by heavy military tracked vehicles. The Santa Maria military Instruction Field, where the experiment was carried out, is currently the most used area for armored tracked vehicles training in Brazil, with the M113 BR being the main equipment. The aim of this study was to determine the effect of the straight line and pivoted traffic intensity of the M113 BR on the physical properties and advancement of the compaction state of an Abruptic Alisol (Argissolo Vermelho-Amarelo Ta Distrófico abrúptico) with military vehicle traffic history. The study was conducted in a completely randomized design, independently evaluating the effect of straight and pivoting traffic in three soil layers (0.00-0.04, 0.10-0.14, and 0.20-0.24 m). For the straight-line traffic, traffic intensities (TI) with one (TI1), two (TI2), and five (TI5) passes on the same trail were evaluated. For the pivoting traffic, TI with one (TI1P) and two (TI2P) pivots was evaluated. Both studies had two non-traffic treatments (NT). The soil bulk density, total porosity, macroporosity, microporosity, saturated soil hydraulic conductivity, soil penetration resistance, soil bearing capacity, preconsolidation pressure, and gravimetric water content were analyzed in this study. In the straight-line traffic, cases with no significant differences in TP, Ma, Mi, and Ks prevailed. The highest TP, smallest Bd and largest Mi were observed in the 0.10-0.14 m layer. In the pivoting traffic, one pass was sufficient to increase Bd and decrease TP, Ma, Mi, and Ks in the 0.00-0.04 m layer and the increase from one to two pivotings had a significant difference only in Mi in this same layer. Both types of traffic intensity did not affect the PR in any layer. The Abruptic Alisol, pre-compacted from long-term military training, supported the loads applied by the M113 BR when additional traffic occurred in straight line mode, but not when in pivoting mode. The preconsolidation pressure parameter was not appropriate to assess the ability of the soil to support loads applied by pivoting traffic.
DOI: 10.6084/m9.figshare.14278301
title: How sulfate content and soil depth affect the adsorption/desorption of selenate and selenite in tropical soils?

description: ABSTRACT Sorption of selenate (SeO 4 2- ) and selenite (SeO 3 2- ) is poorly understood in Brazilian agroecosystems, especially in soils from agricultural areas containing different contents of competing anions, such as sulfate (SO 4 2- ). This study aimed to assess the sorption behavior of selenate and selenite at different soil layers of a tropical soil treated with different rates of agricultural gypsum (thus, containing different contents of sulfate), collected under a coffee plantation. Soil samples from an experimental area where phosphogypsum has been previously applied at different rates (0, 7, 14, and 56 t ha -1 ) were taken at the following soil layers: 0.15-0.25, 0.35-0.45, and 1.25-1.35 m. Adsorption experiments were carried out adding 20 mL of solutions containing 100 and 500 μg L -1 of selenate and 10 and 15 mg L -1 of selenite to 2 grams of soil. Desorption experiments were also performed using a soil:solution ratio of 1:10. Adsorption of selenate increased with soil depth and decreased upon increasing sulfate contents in the soil, by contrast, selenite was consistently adsorbed at higher contents - when compared with selenate - at any soil depth and its sorptive behavior was not affected by the presence of sulfate. Furthermore, selenite was less desorbed than selenate under all conditions. In conclusion, selenite is much more retained in tropical soils and less available to plants than selenate. Also, although sulfate has shown to be able to hinder selenate retention, it has no substantial effect on the sorption behavior of selenite in tropical agroecosystems.
DOI: 10.6084/m9.figshare.14278304
title: Analysis of changes in volume and propagation of cracks in expansive soil due to changes in water content

description: ABSTRACT Expansive clay soils are a problem for agriculture and engineering because they are susceptible to change in volume due to seasonal variation in water content and temperature. One of its morphological properties is slickensides, which result from the ability to contract and crack when dry and expand by wetting. The objective of this study was to evaluate the processes of expansion and formation and propagation of cracks due to the change in water content over time. The expansion process was evaluated through simple edometric tests with different external stress values applied to undisturbed soil samples. To evaluate the shrinking process, a device was developed to monitor the process of crack propagation. The mechanisms through which cracks begin and develop were studied using molded soil samples at the liquidity limit and at 1.25 times the liquidity limit with a drying and wetting cycle. Crack initiation conditions and development of geometric crack indices were measured with the water content and drying time. The soil presented medium to high expansion that depends on the overburden and suction applied, and the swelling stress was found to increase as suction increases. The changes in volume due to wetting and the propagation of cracks due to drying developed in three stages: initial, primary, and secondary. In the initial stage, few cracks or swelling occur with gradual variation in water content. As the water content approaches the limit of soil contraction (in the drying process) or the limit of soil saturation (in the wetting process), cracks and expansion developed slowly and approach a secondary stage. In the primary stage, cracks and expansion occurred rapidly with drying or wetting, respectively. Drying and wetting cycles showed similar crack patterns with the appearance of new micro-cracks during each new drying cycle.