cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.14278263
title: Sample design effects on soil unit prediction with machine: randomness, uncertainty, and majority map

description: ABSTRACT Notwithstanding the importance of soil surveys, advances in digital soil mapping have mainly focused on mapping soil attributes or properties rather than developing digital maps of soil units or soil classes. The purpose of this research was to develop digital soil unit maps based on primary soil data collection in areas without previously collected soil information. The covariate variability, the random effect across the data subset and the map outputs were the focuses of this study. We used five datasets with four models (Random Forest - RF, Gradient Boosted Machine - GBM, C5.0, and multinomial log-linear model - MLR). The covariates were grouped into five datasets, where four were grouped by Region Of Interest per Class (ROIC) and one was not grouped by ROIC. To evaluate the random effect to split the dataset, we ran each model 50 times and observed the overall accuracy (OA) and kappa index, and uncertainty, majority and variety maps. The OA of Dataset01 to 04 was lower than to Dataset05 accuracy. However, map outputs of RF and GBM for Dataset01 and Dataset05 had the same majority prediction. It seems that RF and GBM produce consistent results in map outputs according to this methodology and pedologist expertise. To evaluate the uncertainty and the consistency of soil unit prediction, we used the majority maps process. Random Forest, similar to GBM, presented the best results. The increase in the number of covariates was not a guarantee of improvement in the OA or in the quality of the map output. Geographic position and distance raster did not improve the map output according to expert evaluation. Because the variance between the ROICs, when the training and validation datasets were split based on it, the subsets are quite different in relation to the covariates, and this is the reason for the worse results of this model, comparing with the Dataset05. On the other hand, when considering one complete dataset not based on ROICs, the variance of training and validation subsets is lower and produced more accurate parameters of quality.
DOI: 10.6084/m9.figshare.14278263.v1
title: Sample design effects on soil unit prediction with machine: randomness, uncertainty, and majority map

description: ABSTRACT Notwithstanding the importance of soil surveys, advances in digital soil mapping have mainly focused on mapping soil attributes or properties rather than developing digital maps of soil units or soil classes. The purpose of this research was to develop digital soil unit maps based on primary soil data collection in areas without previously collected soil information. The covariate variability, the random effect across the data subset and the map outputs were the focuses of this study. We used five datasets with four models (Random Forest - RF, Gradient Boosted Machine - GBM, C5.0, and multinomial log-linear model - MLR). The covariates were grouped into five datasets, where four were grouped by Region Of Interest per Class (ROIC) and one was not grouped by ROIC. To evaluate the random effect to split the dataset, we ran each model 50 times and observed the overall accuracy (OA) and kappa index, and uncertainty, majority and variety maps. The OA of Dataset01 to 04 was lower than to Dataset05 accuracy. However, map outputs of RF and GBM for Dataset01 and Dataset05 had the same majority prediction. It seems that RF and GBM produce consistent results in map outputs according to this methodology and pedologist expertise. To evaluate the uncertainty and the consistency of soil unit prediction, we used the majority maps process. Random Forest, similar to GBM, presented the best results. The increase in the number of covariates was not a guarantee of improvement in the OA or in the quality of the map output. Geographic position and distance raster did not improve the map output according to expert evaluation. Because the variance between the ROICs, when the training and validation datasets were split based on it, the subsets are quite different in relation to the covariates, and this is the reason for the worse results of this model, comparing with the Dataset05. On the other hand, when considering one complete dataset not based on ROICs, the variance of training and validation subsets is lower and produced more accurate parameters of quality.
DOI: 10.6084/m9.figshare.14278013
title: Salt leaching efficiency of subsurface drainage systems

description: The study evaluates an approach for increasing the leaching efficiency through the use of a low-permeability surface mulch above the drain.
DOI: 10.6084/m9.figshare.14278265
title: Abundance and diversity of beetles (Insecta: Coleoptera) in land use and management systems

description: ABSTRACT Soil beetles’ communities are responsible for many ecosystem services, and are very sensitive to environmental changes. Thus, this study aimed to evaluate the abundance and diversity of the soil coleoptera fauna under uses and management and also to identify relationships of the beetle community with soil’s physical and chemical properties. The experiment had six experimental plots set up an Oxisol (Latossolo): corn (CO), soybean (SO), 7-year-old eucalyptus (EI), 4-year-old eucalyptus (EII), preserved Cerrado (PC), and disturbed Cerrado (DC). Soil beetles were sampled at 128 points for each experimental plot, where the soil physical and chemical properties were analyzed. The Coleoptera fauna organisms were identified at the family, subfamily, and gender level, and then, the number of individuals per day, richness, Shannon diversity indexes, and Pielou evenness were determined. The data were analyzed using multivariate techniques (hierarchical grouping and factor analysis). On total, 750 specimens of beetles were collected, distributed into 9 families, 14 subfamilies, and 27 genera. The most abundant family was Scarabaeidae (11 genera) with the highest occurrence in the PC (143 specimens) and DC (81 specimens). Cultivation with SO presented the greatest number of trap day individuals (ind trap-1 day-1 = 0.548); however, the highest diversity was found in the PC. (20 taxonomic groups) and CO (16 taxonomic groups). Shannon diversity was higher for the CO (H’ = 3.107), followed by the PC (H’ = 2.699), and the lowest value was found for the SO (H’ = 1.530). The similarity dendrogram grouped the plots into two extracts, demonstrating how the intensity of land use influences the abundance and diversity of beetle fauna. The factor analysis grouped the Coleoptera and the physical and chemical soil properties in two factors: elements related to the state of aggregation and porous system’s elements. The Coleoptera community was influenced by the intensity of land use and the portion with anthropized natural vegetation showed the highest richness, demonstrating that the Coleoptera fauna responds to environmental changes. Edaphic beetles in the different use and management systems were primarily related to soil physical properties, which explain the state of aggregation (pH, altitude, Ca2+, BD, clay, macroporosity, silt, K+, and microporosity) and the porous soil system (sand and total porosity).
DOI: 10.6084/m9.figshare.14278265.v1
title: Abundance and diversity of beetles (Insecta: Coleoptera) in land use and management systems

description: ABSTRACT Soil beetles’ communities are responsible for many ecosystem services, and are very sensitive to environmental changes. Thus, this study aimed to evaluate the abundance and diversity of the soil coleoptera fauna under uses and management and also to identify relationships of the beetle community with soil’s physical and chemical properties. The experiment had six experimental plots set up an Oxisol (Latossolo): corn (CO), soybean (SO), 7-year-old eucalyptus (EI), 4-year-old eucalyptus (EII), preserved Cerrado (PC), and disturbed Cerrado (DC). Soil beetles were sampled at 128 points for each experimental plot, where the soil physical and chemical properties were analyzed. The Coleoptera fauna organisms were identified at the family, subfamily, and gender level, and then, the number of individuals per day, richness, Shannon diversity indexes, and Pielou evenness were determined. The data were analyzed using multivariate techniques (hierarchical grouping and factor analysis). On total, 750 specimens of beetles were collected, distributed into 9 families, 14 subfamilies, and 27 genera. The most abundant family was Scarabaeidae (11 genera) with the highest occurrence in the PC (143 specimens) and DC (81 specimens). Cultivation with SO presented the greatest number of trap day individuals (ind trap-1 day-1 = 0.548); however, the highest diversity was found in the PC. (20 taxonomic groups) and CO (16 taxonomic groups). Shannon diversity was higher for the CO (H’ = 3.107), followed by the PC (H’ = 2.699), and the lowest value was found for the SO (H’ = 1.530). The similarity dendrogram grouped the plots into two extracts, demonstrating how the intensity of land use influences the abundance and diversity of beetle fauna. The factor analysis grouped the Coleoptera and the physical and chemical soil properties in two factors: elements related to the state of aggregation and porous system’s elements. The Coleoptera community was influenced by the intensity of land use and the portion with anthropized natural vegetation showed the highest richness, demonstrating that the Coleoptera fauna responds to environmental changes. Edaphic beetles in the different use and management systems were primarily related to soil physical properties, which explain the state of aggregation (pH, altitude, Ca2+, BD, clay, macroporosity, silt, K+, and microporosity) and the porous soil system (sand and total porosity).
DOI: 10.6084/m9.figshare.14278269
title: Using root water uptake estimated by a hydrological model to evaluate the least limiting water range

description: ABSTRACT The least limiting water range (LLWR) has been extensively determined, but evaluating if LLWR can indeed indicate soil physical stress on plant growth is still a controversial issue. In this study, we used the Hydrus-1D hydrological model to simulate root water uptake (RWU) to analyze if RWU and LLWR are correlated under stress conditions. The LLWR was determined in a sandy-loam Ultisol and a clayey Oxisol. In both soils, RWU extracted by plants (leaf area index set as 3) from a rooted layer of 0.4 m was simulated over 20 days under a potential evapotranspiration rate of 6 mm day-1. For each soil, RWU was simulated over the same range of soil compaction in which LLWR was determined. The cumulative RWU over the 20 days varied between 23 to 58 mm in the Ultisol and 20 to 48 mm in the Oxisol, indicating that plants were able to take up only a small part of the cumulative potential transpiration (93 mm) and experienced severe water stress in some soil conditions. However, RWU under water stress was poorly correlated with both bulk density and LLWR. The correlation between RWU and LLWR was 0.5 (p&lt;0.01) for the Ultisol and 0.22 (p&lt;0.19) for the Oxisol, suggesting that LLRW has little (for Ultisol) or almost no (for Oxisol) ability to indicate soil quality related to plant water availability. Our simulations suggest that RWU in the water availability range (between field capacity and wilting point) may be little affected or even improved by light soil compaction. Studies to elucidate this phenomenon would contribute to the understanding of the compaction effect on RWU and the weak correlation between RWU and LLWR.
DOI: 10.6084/m9.figshare.14278253.v1
title: Association of Post-Barreiras and Barreiras Formation strata and influence on soil genesis, Southern Bahia – Brazil

description: ABSTRACT The term Post-Barreiras is a definition for sediments above the deposits of the Barreiras Formation, and the genesis of soils in these environments must be related to sedimentary deposition. Our objective was to apply multi-technique analyses to characterize the sediments and soils to understand pedogenesis in these environments. We analysed sedimentological parameters and the geochronology of sediments. Morphological, chemical, and mineralogical analyses allowed the characterization of the soil. Also, these data supported the analysis of lithological discontinuity. We considered the contents of Ti and Zr, uniformity value, the fraction of organic material, morphology, and palynological analysis. The age of Post-Barreiras sediments is from the Pleistocene, and they have a more significant variation of sedimentological parameters concerning Barreiras Formation layers. In general, the soils are sandy, acidic, have a low level of exchangeable cations. Mineralogy has a predominance of quartz and kaolinite minerals. In the region, there are soils with low morphological variation, classified as Quartzipsamments. In other cases, there are soils with apparent spodic morphology, which is conditioned by four aspects: (i) Podzolization in Post-Barreiras sandy sediments without evidence of lithological discontinuity, forming Bs horizon (Spodosols); (ii) contact zones (Post-Barreiras/Barreiras Formation) with physical, chemical, and morphological evidence of discontinuity, forming Quartzipsamments or Ultisols; (iii) layers of the Barreiras Formation buried by Post-Barreiras sediments and the subsequent podzolization process, forming Bhm horizon (Spodosols); and (iv) destruction of Ultisols clay, forming Bs horizon (Spodosols). The sedimentary association (Post-Barreiras/Barreiras Formation) favors the development of different soils. The contact zones generate a morphological aspect similar to the Spodosols, associated or not with podzolization processes.
DOI: 10.6084/m9.figshare.14278268.v1
title: Calcination as an alternative method to classify Spodosols on the second categorical level

description: ABSTRACT The classification of Spodosols on the second categorical level (suborder), according to the Brazilian Soil Classification System (SiBCS), is done by observing the colors of genetic horizons in the field. The presence or absence of iron oxides is the main factor for this classification, and the color of the horizon is the criterion currently adopted. However, the simple observation of color in the field can be mistaken and cause an error in the definition of the second categorical level. This occurs when spodic horizons that do not contain iron oxides show high chroma color, or dark color due to the organic matter content, which masks the presence of iluviated Fe produced by podzolization. This can lead to errors, such as classifying Humiluvico horizons as Ferriluvico, and Ferri-humiluvico horizons as Humiluvico. These misunderstandings are currently solved through complex analyses using specific extractors and sophisticated equipment. Thus, obtaining a simple, fast, and inexpensive method to confirm the presence or absence of iron oxides in samples of spodic horizons is needed. This study tested an alternative method to assist in the determination of the second categorical level of the class of coastal plain Spodosols. The method consists of calcining samples in a muffle at 600 °C for 6 h. The calcination enabled to identify spodic horizons with and without presence of iron quickly; the result was compared with selective extraction analyses carried out using three different extractors: sodium pyrophosphate, ammonium acid oxalate, and sodium dithionite-citrate. The results obtained from these methods (calcination in muffle and selective extraction of iron oxides) enabled the identification of samples presenting colors varying from yellow to reddish, indicating the presence of iron, whereas those with the whitish color indicated absence or very low iron oxide levels. The 12 profiles of Spodosols were described and classified according to the SiBCS, and six profiles needed to be reclassified after the calcination procedure, which proved to be efficient.
DOI: 10.6084/m9.figshare.14278269.v1
title: Using root water uptake estimated by a hydrological model to evaluate the least limiting water range

description: ABSTRACT The least limiting water range (LLWR) has been extensively determined, but evaluating if LLWR can indeed indicate soil physical stress on plant growth is still a controversial issue. In this study, we used the Hydrus-1D hydrological model to simulate root water uptake (RWU) to analyze if RWU and LLWR are correlated under stress conditions. The LLWR was determined in a sandy-loam Ultisol and a clayey Oxisol. In both soils, RWU extracted by plants (leaf area index set as 3) from a rooted layer of 0.4 m was simulated over 20 days under a potential evapotranspiration rate of 6 mm day-1. For each soil, RWU was simulated over the same range of soil compaction in which LLWR was determined. The cumulative RWU over the 20 days varied between 23 to 58 mm in the Ultisol and 20 to 48 mm in the Oxisol, indicating that plants were able to take up only a small part of the cumulative potential transpiration (93 mm) and experienced severe water stress in some soil conditions. However, RWU under water stress was poorly correlated with both bulk density and LLWR. The correlation between RWU and LLWR was 0.5 (p&lt;0.01) for the Ultisol and 0.22 (p&lt;0.19) for the Oxisol, suggesting that LLRW has little (for Ultisol) or almost no (for Oxisol) ability to indicate soil quality related to plant water availability. Our simulations suggest that RWU in the water availability range (between field capacity and wilting point) may be little affected or even improved by light soil compaction. Studies to elucidate this phenomenon would contribute to the understanding of the compaction effect on RWU and the weak correlation between RWU and LLWR.
DOI: 10.6084/m9.figshare.14278271
title: Diversity and abundance of soil macrofauna in three land use systems in eastern Amazonia

description: ABSTRACT Given the influence of edaphic macrofauna in the physical, chemical, and biological processes that sustain the organic matter cycle in the soil of tropical ecosystems, this study aimed to evaluate the effect of the sequence: Secondary Forest – Pasture – Eucalyptus monoculture on the macrofauna structure in Southeast of Pará State, Brazil. In each land use system, two 350 m transect were taken. The data was collected in 8 sampling sites, which were 50 m apart in each transect at 0.10 and 0.20 m depths. Correlations between the community structure Family Richness (S), Shannon-Wiener diversity index (H’), Pielou equitability (J), and macrofauna density (ind. m-2) were tested with soil pH(H2O), Al3+, Ca2+, Mg2+, K+, P, SOC, N, Fe, Zn, and Mn and the litter dry matter total content of Ca, Mg, K, P, TOC., N, Fe, Zn. The land use has affected the macrofauna community parameters S, H’, and J (p&lt;0.05). The macrofauna density did not differ between land use systems Pasture and Secondary Forest (p&gt;0.05). The evaluated indexes were highly correlated with the disturbance level, increasing gradually from the Pasture, where the lowest levels were found, to the Secondary Forest with the best indexes in this study, with 29 families exclusive to this land use system. Correlations between the community structure and soil and litter chemical parameters were not detected.
DOI: 10.6084/m9.figshare.14278274
title: Comparison of field measurement methods of nitrous oxide soil emissions: from the chamber to the vial

description: ABSTRACT Nitrous oxide (N2O) is a greenhouse gas that contributes substantially to global climate change. The N2O soil emissions have a large uncertainty because of its low atmospheric concentration levels and enormous spatial and temporal variability, which hinders its correct field measurement. For this reason, there are many papers focused on improving the N2O measurements in the field, which focus on different parts of the measurement process. However, no studies have focused on determining the appropriate method, in terms of simplicity and precision, for the sample extraction from inside of the chambers and its transfer to the storage vials, although this step is key in the sampling process. This study aimed to assess and compare the accuracies of three simple and economical methods in transfer soil emitted N2O from inside of the chambers to the vials. For this, a highly accepted method (vacuum by manual pump) and two simpler alternative methods (gas exchange by displacement and vacuum by syringe) were compared. Thirty static chambers were assessed with the quantified N2O emission values varied from 0 to 450 µg m-2 h-1 of N-N2O. Out of the three assessed methods, the vacuum method through the use of a manual vacuum pump was the best to quantifying N2O soil emissions (capturing 57 % of the highest emission values), followed by the gas exchange method by displacement (30 %), and finally by the vacuum method by syringe extraction (13%).
DOI: 10.6084/m9.figshare.14278268
title: Calcination as an alternative method to classify Spodosols on the second categorical level

description: ABSTRACT The classification of Spodosols on the second categorical level (suborder), according to the Brazilian Soil Classification System (SiBCS), is done by observing the colors of genetic horizons in the field. The presence or absence of iron oxides is the main factor for this classification, and the color of the horizon is the criterion currently adopted. However, the simple observation of color in the field can be mistaken and cause an error in the definition of the second categorical level. This occurs when spodic horizons that do not contain iron oxides show high chroma color, or dark color due to the organic matter content, which masks the presence of iluviated Fe produced by podzolization. This can lead to errors, such as classifying Humiluvico horizons as Ferriluvico, and Ferri-humiluvico horizons as Humiluvico. These misunderstandings are currently solved through complex analyses using specific extractors and sophisticated equipment. Thus, obtaining a simple, fast, and inexpensive method to confirm the presence or absence of iron oxides in samples of spodic horizons is needed. This study tested an alternative method to assist in the determination of the second categorical level of the class of coastal plain Spodosols. The method consists of calcining samples in a muffle at 600 °C for 6 h. The calcination enabled to identify spodic horizons with and without presence of iron quickly; the result was compared with selective extraction analyses carried out using three different extractors: sodium pyrophosphate, ammonium acid oxalate, and sodium dithionite-citrate. The results obtained from these methods (calcination in muffle and selective extraction of iron oxides) enabled the identification of samples presenting colors varying from yellow to reddish, indicating the presence of iron, whereas those with the whitish color indicated absence or very low iron oxide levels. The 12 profiles of Spodosols were described and classified according to the SiBCS, and six profiles needed to be reclassified after the calcination procedure, which proved to be efficient.