Permafrost slows Arctic riverbank erosion.

The rate of river migration affects the stability of Arctic infrastructure and communities1,2 and regulates the fluxes of carbon3,4, nutrients5 and sediment6,7 to the oceans. However, predicting how the pace of river migration will change in a warming Arctic8 has so far been stymied by conflicting observations about whether permafrost9 primarily acts to slow10,11 or accelerate12,13 river migration. Here we develop new computational methods that enable the detection of riverbank erosion at length scales 5-10 times smaller than the pixel size in satellite imagery, an innovation that unlocks the ability to quantify erosion at the sub-monthly timescales when rivers undergo their largest variations in water temperature and flow. We use these high-frequency observations to constrain the extent to which erosion is limited by the thermal condition of melting the pore ice that cements bank sediment14, a requirement that will disappear when permafrost thaws, versus the mechanical condition of having sufficient flow to transport the sediment comprising the riverbanks, a condition experienced by all rivers15. Analysis of high-resolution data from the Koyukuk River, Alaska, shows that the presence of permafrost reduces erosion rates by 47%. Using our observations, we calibrate and validate a numerical model that can be applied to diverse Arctic rivers. The model predicts that full permafrost thaw may lead to a 30-100% increase in the migration rates of Arctic rivers.

Cost-effectiveness of erosion mitigation to meet water clarity targets in the Manawatu-Whanganui Region of New Zealand.

Soil erosion is a significant environmental issue worldwide. It affects water quality, biodiversity, and land productivity. New Zealand government agencies and regional councils work to mitigate soil erosion through policies, management programmes, and funding for soil conservation projects. Information about cost-effectiveness is crucial for planning, targeting, and implementing erosion mitigation to achieve improvements in sediment-related water quality. While there is a good understanding of the costs of erosion mitigation measures, there is a dearth of literature on their cost-effectiveness in reducing sediment loads and improving water quality at the catchment level. In this study, we estimate the cost-effectiveness of erosion mitigation measures in meeting visual water clarity targets. The analysis utilizes the spatially explicit SedNetNZ erosion process and sediment budget modelling in the Manawatu-Whanganui Region and region-specific mitigation costs. The erosion mitigation measures considered in the analysis include afforestation, bush retirement, riparian retirement, space-planted trees, and gully tree planting. We modelled two scenarios with on-farm erosion mitigation implemented across the region from 2021 to 2100, resulting in a 48% and 60% reduction of total sediment load. We estimate the marginal costs to achieve the visual national bottom line for water clarity, as assessed by the length of waterways that meet the clarity targets. We also estimate the marginal costs of improving average water clarity, which can be linked with non-market valuation studies when conducting a cost-benefit analysis. We find that gully tree planting and space-planted trees are the most cost-effective mitigation measures and that riparian retirement is the least cost-effective. Moreover, cost-effectiveness is highly dependent on current land use and the biophysical features of the landscape. Our estimates can be used in cost-benefit analysis to plan and prioritize soil erosion mitigation at the catchment and regional levels.

[Effect of freeze-thaw cycles on aggregate breakdown of typical black soil during transportation]. / å†»èžå¯¹å ¸åž‹é»‘åœŸå›¢èšä½“è¾“ç§»ç ´ç¢Žç‰¹å¾çš„å½±å“.

During the snowmelt period, the external erosive forces are dominated by freeze-thaw cycles and snowmelt runoff. These forces may affect soil structure and aggregate stability, thereby influencing snowmelt erosion. The process of snowmelt runoff can lead to the breakdown of aggregates during their transportation. However, few studies examined the effects of freeze-thaw cycles on the breakdown of aggregates during transportation. Focusing on 5-7 and 3-5 mm soil aggregates of typical black soil region in Northeast China, we analyzed the composition of water-stable aggregates, mean weight diameter (MWD), normalized mean weight diameter (NMWD), as well as breakdown rate of soil aggregates (BR) under different freeze-thaw cycles (0, 1, 5, 10, 15 and 20 times) and different transport distances (5, 10, 15, 20, 25 and 30 m). We further investigated the contribution (CT) of both freeze-thaw cycles and transport distances to BR. The results showed that: 1) After freeze-thaw cycles, the 5-7 and 3-5 mm aggregates were mainly composed of particles with a diameter of 0.5-1 mm. With increasing frequency of freeze-thaw cycles, the MWD generally showed a downward trend. Moreover, under the same number of freeze-thaw cycles, the NMWD of 3-5 mm aggregates was higher than that of 5-7 mm aggregates. 2) As the transport distance increased, the BR of 5-7and 3-5 mm aggregates gradually increased. Compared that under control group, the BR under one freeze-thaw cycle increased by 59.7%, 32.2%, 13.7%, 6.2%, 13.4%, 7.5%, and 60.0%, 39.0%, 18.4%, 13.0%, 6.3%, 6.1% at the condition of 5, 10, 15, 20, 25 and 30 m transport distances, respectively. However, with increasing frequency of freeze-thaw cycles, the BR increased slowly. 3) The breakdown of soil aggregates was mainly influenced by the transport distance (CT=54.6%) and freeze-thaw cycles (CT=26.2%). Freeze-thaw cycles primarily altered the stability of soil aggregates, which in turn affected the BR. Therefore, during the snowmelt period, freeze-thaw cycles reduced the stability of soil aggregates, leading to severe breakdown of soil aggregates during snowmelt runoff process. This made the soil more susceptible to migration with snowmelt runoff, which triggered soil erosion. Therefore, more attention should be paid on the prevention of soil erosion during snowmelt period.

[Rainwater harvesting effect of biocrusted soil-surfaces and the key influencing factors in the hilly region of Chinese Loess Plateau]. / é»„åœŸä¸˜é™µåŒºç”Ÿç‰©ç»“çš®é›†é›¨é¢çš„é›†é›¨æ•ˆæžœåŠå ¶å ³é”®å½±å“å› å­.

In the hilly region of Chinese Loess Plateau, rainwater harvesting is a common ecological engineering measure utilized to reduce soil erosion and amplify the efficiency of water resource utilization. However, the effects on rainwater harvesting and the chief influencing factors of biocrusts as a potential material are unclear. In this study, we conducted a field simulation experiment with intensities of 40, 60, 80, and 100 mm·h-1 between bare soil and biocrusts developed in aeolian soils, with bare soil as a control to explore the differences of the initial abstraction time, cumulative rainfall amount, and rainfall harvesting efficiency. We further analyzed the influencing factors of the rainwater harvesting effect. The results showed that the biocrusted soil-surfaces significantly decreased the initial abstraction time. When compared with the cyano biocrusts and bare soil, the reduction of the initial abstraction time of moss biocrusts was decreased by 49.7%-77.5% and 89.7%-110.0% when the rainfall intensities ranged from 40 to 100 mm·h-1 and the slope was 40°. In addition, biocrusted soil surfaces significantly increased the cumulative rainfall amount and rainfall harvesting efficiency. These differences were considerable amongst the dissimilar surface cover types. In comparison to bare soil, when the rainfall intensity was 100 mm·h-1 and the slope was 40°, the cumulative rainfall harvesting efficiency of moss and cyano biocrusts was increased by 29.6% and 7.8%, respectively. Both moss and cyano biocrusts increased rainfall harvesting efficiency of 25.7% and 6.8%, respectively. Variance analysis demonstrated that the rainfall harvesting efficiency was appreciably affected by surface cover type, slope, and rainfall intensity. The interaction between these factors was considerable except for slope and rainfall intensity. Additionally, important considerations for the actual construction included slope length, slope, and biocrust cultivation. In conclusion, biocrusted soil-surfaces have a high rainfall harvesting efficiency, but moss biocrusts have a much greater rain-collecting effect that improves even more as the slope and intensity of the rain increases.

Plant structural diversity alters sediment retention on and underneath herbaceous vegetation in a flume experiment.

Sediment retention is a key ecosystem function provided by floodplains to filter sediments and nutrients from the river water during floods. Floodplain vegetation is an important driver of fine sediment retention. We aim to understand which structural properties of the vegetation are most important for capturing sediments. In a hydraulic flume experiment, we investigated this by disentangling sedimentation on and underneath 96 vegetation patches (40 cm x 60 cm). We planted two grass and two herb species in each patch and conducted a full-factorial manipulation of 1) vegetation density, 2) vegetation height, 3) structural diversity (small-tall vs tall-tall species combinations) and 4) leaf pubescence (based on trait information). We inundated the vegetation patches for 21 h in a flume with silt- and clay-rich water and subsequently measured the amount of accumulated sediment on the vegetation and on a fleece as ground underneath it. We quantified the sediment by washing it off the biomass and off the fleece, drying the sediment and weighting it. Our results showed that all manipulated vegetation properties combined (vegetation density and height, and the interaction of structural diversity and leaf pubescence) explained sedimentation on the vegetation (total R2 = 0.34). The sedimentation underneath the vegetation was explained by the structural diversity and the leaf pubescence (total R2 = 0.11). We further found that vegetation biomass positively affected the sedimentation on and underneath the vegetation. These findings are crucial for floodplain management strategies with the aim to increase sediment retention. Based on our findings, we can identify management strategies and target plant communities that are able to maximize a floodplain's ability to capture sediments.

Prediction of sediment transport capacity based on slope gradients and flow discharge.

Sediment transport capacity (Tc) is an essential parameter in the establishment of the slope soil erosion model. Slope type is an important crucial factor affecting sediment transport capacity of overland flow, and vegetation can effectively inhibit soil loss. Two new formulae of sediment transport capacity (Tc) are proposed of brown soil slope and vegetation slope in this study and evaluate the influence of slope gradient (S) and flow discharge (Q) on sediment transport capacity of different slope types. Laboratory experiments conducted using four flow discharges (0.35, 0.45, 0.55, and 0.65 L s-1), four slope gradients (3, 6, 9, and 12°), and two kinds of underlying surface (Brown soil slope, Vegetation slope). The soil particle size range is 0.05-0.5mm. The vegetation stems were 2mm in diameter and randomly arranged. The results show that the sediment transport capacity was positively correlated with the flow discharge and slope gradient. The vegetation slope's average sediment transport capacity is 11.80% higher than the brown soil slope that same discharge and slope gradient conditions. The sensitivity of sediment transport capacity to flow discharge on brown soil slope is higher than that of slope gradient. The sensitivity of sediment transport capacity of vegetation slope to slope gradient is more heightened than flow discharge. The sediment transport capacity was well predicted by discharge and slope gradient on brown soil slope (R2 = 0.982) and vegetation slope (R2 = 0.993). This method is helpful to promote the study of the sediment transport process on overland flow.

Assessing spatial variability of soil organic carbon and total nitrogen in eroded hilly region of subtropical China.

The hilly red soil region of southern China suffers from severe soil erosion that has led to soil degradation and loss of soil nutrients. Estimating the content and spatial variability of soil organic carbon (SOC) and soil total nitrogen (STN) and assessing the influence of topography and land-use type on SOC and STN after years of soil erosion control are important for vegetation restoration and ecological reconstruction. A total of 375 topsoil samples were collected from Changting County, and their SOC and STN distributions were studied by using descriptive statistics and geostatistical methods. Elevation, slope, aspect and land-use type were selected to investigate the impacts of natural and human factors on the spatial heterogeneity of SOC and STN. The mean SOC and STN concentrations were 15.85 and 0.98 g kg-1 with moderate spatial variations, respectively. SOC and STN exhibited relatively uniform distributions that decreased gradually from the outside parts to the center of the study area. The SOC and STN contents in the study area were still at moderate and low levels after years of erosion control, which suggests that soil nutrient improvement is a slow process. The lowest SOC and STN values were at lower elevations in the center of Changting County. The results indicated that the SOC and STN contents increased most significantly with elevation and slope due to the influence of topography on the regional natural environment and soil erosion in the eroded hilly region. No significant variations were observed among different slope directions and land-use types.

Micro-scale interactions between Arabidopsis root hairs and soil particles influence soil erosion.

Soil is essential for sustaining life on land. Plant roots play a crucial role in stabilising soil and minimising erosion, although these mechanisms are still not completely understood. Consequently, identifying and breeding for plant traits to enhance erosion resistance is challenging. Root hair mutants in Arabidopsis thaliana were studied using three different quantitative methods to isolate their effect on root-soil cohesion. We present compelling evidence that micro-scale interactions of root hairs with surrounding soil increase soil cohesion and reduce erosion. Arabidopsis seedlings with root hairs were more difficult to detach from soil, compost and sterile gel media than those with hairless roots, and it was 10-times harder to erode soil from roots with than without hairs. We also developed a model that can consistently predict the impact root hairs make to soil erosion resistance. Our study thus provides new insight into the mechanisms by which roots maintain soil stability.

Soil losses in the State of Rondônia, Brazil / Perdas de solo no Estado de Rondônia, Brasil

In the state of Rondônia, deforestation, and inadequate soil use and management have intensified the water erosion process, causing degradation of agricultural land. Modeling is a tool that can assist in the adoption of targeted and effective measures for soil and water conservation in the region. In this context, the objective of the research was to model soil losses due to water erosion in the state of Rondônia using the Revised Universal Soil Loss Equation (RUSLE). The parameters related to rain erosivity, relief, erodibility, and soil cover, as well as the conservation practices of the state of Rondônia, were considered. The modeling steps were performed with the aid of the Geographic Information System. Results were validated with data of total sediments transported with water discharge. The estimated total soil loss was about 605 million tons per year, corresponding to an average loss of 22.50 Mg ha-1 year-1. In 19% of the state, the erosion rate was higher than the soil loss tolerance(T), and these areas should be prioritized for adopting measures to mitigate the erosion process. The RUSLE underestimated the generation of sediments at 0.56 Mg ha-1 year-1, which corresponds to an error of 18.60%. Results obtained can assist in the development of different soil use and management scenarios and provide options for policymakers to encourage soil conservation in the state of Rondônia.(AU)

No Estado de Rondônia, o desmatamento, o uso e o manejo inadequado dos solos têm intensificado o processo de erosão hídrica, gerando a degradação de terras agrícolas. Nesse cenário, a modelagem é uma ferramenta que pode auxiliar na adoção de medidas direcionadas e eficazes de conservação do solo e da água na região. Assim, o objetivo do trabalho foi modelar as perdas de solo por erosão hídrica no Estado de Rondônia utilizando a Equação Universal de Perda de Solo Revisada (RUSLE). Foram considerados os parâmetros referentes a erosividade da chuva, relevo, erodibilidade e cobertura do solo e as práticas conservacionistas do Estado de Rondônia. As etapas da modelagem foram realizadas com auxílio de Sistema de Informações Geográficas. Os resultados foram validados com dados de coleta de sedimentos totais transportados com a descarga dágua. A perda de solo total estimada foi cerca de 605 milhões de toneladas ao ano, correspondente a uma perda média de 22,50 Mg ha-1 ano-1. Em 19% do Estado a taxa erosiva foi superior aos limites de tolerância de perda de solo (TPS), sendo que essas áreas devem ser priorizadas para adoção de medidas de mitigação do processo erosivo. A RUSLE subestimou a geração de sedimentos em 0,56 Mg ha-1 ano-1, o que corresponde a um erro de 18,60%. Os resultados obtidos podem contribuir para elaborar distintos cenários de manejo e uso do solo e fornecer alternativas aos formuladores de políticas agrícolas e ambientais, com o intuito de incentivo a conservação do solo no Estado de Rondônia.(AU)

Tracing the origin of reservoir sediments using magnetic properties in Southeastern Brazil / Traçando a origem de sedimentos de reservatórios usando propriedades magnéticas no Sudeste do Brasil

Determining the origin of eroded soil is essential to design effective soil erosion control strategies which preserve the soil resource, enhance agricultural productivity, and reduce the negative impacts of soil erosion, in-field and off-field. Magnetic properties have been widely used in temperate environments to identify sediment sources, pathways and links, but there have been very few applications in tropical and subtropical environments. Therefore, in this paper we investigated reservoir sediment sources in the Upper Grande River Basin, Southeastern Brazil, using sediment tracing techniques based on magnetic parameters (low and high frequency magnetic susceptibility, frequency dependent susceptibility). The different parent materials and subtropical weathering conditions resulted in soils having different Fe oxide minerals and Fe oxide contents, promoting magnetic variability that allowed comparison and identification of possible sources of reservoir sediments in order to reduce water erosion impacts. The results indicate the suitability of magnetic properties as a tracer for soil erosion studies in tropical environments.(AU)

Determinar a origem de solos erodidos é essencial para projetar estratégias efetivas de controle da erosão do solo que preservem os recursos do solo, aumentem a produtividade agrícola e reduzam os impactos negativos da erosão do solo, em campo e fora dele. As propriedades magnéticas têm sido amplamente utilizadas em ambientes temperados para identificar fontes, vias e elos de sedimentos, mas existem pouquíssimas aplicações em ambientes tropicais. Portanto, neste trabalho investigamos fontes de sedimentos de reservatórios na Bacia do Alto Rio Grande, Sudeste do Brasil, utilizando técnicas de rastreamento de sedimentos baseadas em parâmetros magnéticos (suscetibilidade magnética de baixa e alta freqüência, susceptibilidade dependente da freqüência). Os diferentes materiais de origem e condições de intemperismo tropical resultaram em solos com diferentes minerais de óxido de Fe e teores de óxidos de Fe, promovendo variabilidade magnética que permitiu a comparação e identificação de possíveis fontes de sedimentos de reservatórios para reduzir os impactos da erosão hídrica. Os resultados indicam a adequação das propriedades magnéticas como um traçador para estudos de erosão do solo em ambientes tropicais.(AU)

Tracing the origin of reservoir sediments using magnetic properties in Southeastern Brazil / Traçando a origem de sedimentos de reservatórios usando propriedades magnéticas no Sudeste do Brasil

Determining the origin of eroded soil is essential to design effective soil erosion control strategies which preserve the soil resource, enhance agricultural productivity, and reduce the negative impacts of soil erosion, in-field and off-field. Magnetic properties have been widely used in temperate environments to identify sediment sources, pathways and links, but there have been very few applications in tropical and subtropical environments. Therefore, in this paper we investigated reservoir sediment sources in the Upper Grande River Basin, Southeastern Brazil, using sediment tracing techniques based on magnetic parameters (low and high frequency magnetic susceptibility, frequency dependent susceptibility). The different parent materials and subtropical weathering conditions resulted in soils having different Fe oxide minerals and Fe oxide contents, promoting magnetic variability that allowed comparison and identification of possible sources of reservoir sediments in order to reduce water erosion impacts. The results indicate the suitability of magnetic properties as a tracer for soil erosion studies in tropical environments.

Determinar a origem de solos erodidos é essencial para projetar estratégias efetivas de controle da erosão do solo que preservem os recursos do solo, aumentem a produtividade agrícola e reduzam os impactos negativos da erosão do solo, em campo e fora dele. As propriedades magnéticas têm sido amplamente utilizadas em ambientes temperados para identificar fontes, vias e elos de sedimentos, mas existem pouquíssimas aplicações em ambientes tropicais. Portanto, neste trabalho investigamos fontes de sedimentos de reservatórios na Bacia do Alto Rio Grande, Sudeste do Brasil, utilizando técnicas de rastreamento de sedimentos baseadas em parâmetros magnéticos (suscetibilidade magnética de baixa e alta freqüência, susceptibilidade dependente da freqüência). Os diferentes materiais de origem e condições de intemperismo tropical resultaram em solos com diferentes minerais de óxido de Fe e teores de óxidos de Fe, promovendo variabilidade magnética que permitiu a comparação e identificação de possíveis fontes de sedimentos de reservatórios para reduzir os impactos da erosão hídrica. Os resultados indicam a adequação das propriedades magnéticas como um traçador para estudos de erosão do solo em ambientes tropicais.

Contribution of the root system of vetiver grass towards slope stabilization of the São Francisco River / Contribuição do sistema radicular do capim-vetiver para estabilização do talude do Rio São Francisco

The control of soil erosion along the banks of the São Francisco River requires the use of efficient and economically viable strategies. Soil bioengineering techniques may be an alternative to the conventional methods as they provide good soil stabilization by mechanical reinforcement promoted by the roots. The objective of this study was to evaluate the contribution of the root cohesion of vetiver grass (Chrysopogon zizanioides (L.) Roberty) on slope stabilization in erosion control along the right margin of the São Francisco river. Seedlings of vetiver grass were planted in the riverbank of the Lower São Francisco located in Sergipe State, northeast Brazil, and plants were sampled after two years of growth to evaluate the effect of grass on the shear strength of the soil. The monolith and cylinder method was used to collect roots for the evaluation of Root Density (RL), Root Length Density (RLD), Root Area Ratio (RAR), Root Tensile Strength (TR), and Root Cohesion (CR). Data were submitted to analysis of variance (p 0.05), with polynomial regression analysis. The results show that for RL, RLD, and RAR, the layers of soil at depths of 0-0.10 m had the highest values of 4.84 kg m-3, 12.45 km m-3, 1.66%, respectively. The mean TR was 83 MPa and CR was 528 kPa. Vetiver increases shear strength of the soil and slope stabilization.(AU)

O controle da erosão marginal do Rio São Francisco requer estratégias eficientes e economicamente viáveis. A técnica de bioengenharia de solos pode ser uma alternativa, visto que proporciona maior estabilização do solo pelo efeito do reforço mecânico promovido pelas raízes das plantas. Esse estudo teve como objetivo avaliar a contribuição à coesão do solo da raiz do capim-vetiver (Chrysopogon zizanioides (L.) Roberty), na estabilidade do talude para controle da erosão da margem direita do Rio São Francisco. Mudas do capim-vetiver foram plantadas no talude da margem direita do Baixo São Francisco no estado de Sergipe, com amostragem das plantas realizada após dois anos do plantio, a fim de avaliar o efeito da gramínea no aumento da resistência ao cisalhamento do solo. Foram utilizadas a metodologia do monólito e o método do cilindro para coleta de raiz, visando à avaliação da Densidade Radicular (DR), Densidade do Comprimento Radicular (DCR), Razão de Raiz por Área (RAR), Resistência de Raízes à Ruptura (TR) e Coesão da Raiz (CR). Os dados foram submetidos à análise de variância (p 0,05), com análise de regressão polinomial. Os resultados mostram que para DR, DCR e RAR, na camada de 0-0,10 m apresentaram valores mais altos de 4,84 kg m-3, 12,45 km m-3, 1,66%, respectivamente. O TR médio foi de 83 MPa e o CR de 528 kPa. O vetiver favorece o aumento da resistência ao...(AU)

Contribution of the root system of vetiver grass towards slope stabilization of the São Francisco River / Contribuição do sistema radicular do capim-vetiver para estabilização do talude do Rio São Francisco

The control of soil erosion along the banks of the São Francisco River requires the use of efficient and economically viable strategies. Soil bioengineering techniques may be an alternative to the conventional methods as they provide good soil stabilization by mechanical reinforcement promoted by the roots. The objective of this study was to evaluate the contribution of the root cohesion of vetiver grass (Chrysopogon zizanioides (L.) Roberty) on slope stabilization in erosion control along the right margin of the São Francisco river. Seedlings of vetiver grass were planted in the riverbank of the Lower São Francisco located in Sergipe State, northeast Brazil, and plants were sampled after two years of growth to evaluate the effect of grass on the shear strength of the soil. The monolith and cylinder method was used to collect roots for the evaluation of Root Density (RL), Root Length Density (RLD), Root Area Ratio (RAR), Root Tensile Strength (TR), and Root Cohesion (CR). Data were submitted to analysis of variance (p 0.05), with polynomial regression analysis. The results show that for RL, RLD, and RAR, the layers of soil at depths of 0-0.10 m had the highest values of 4.84 kg m-3, 12.45 km m-3, 1.66%, respectively. The mean TR was 83 MPa and CR was 528 kPa. Vetiver increases shear strength of the soil and slope stabilization.

O controle da erosão marginal do Rio São Francisco requer estratégias eficientes e economicamente viáveis. A técnica de bioengenharia de solos pode ser uma alternativa, visto que proporciona maior estabilização do solo pelo efeito do reforço mecânico promovido pelas raízes das plantas. Esse estudo teve como objetivo avaliar a contribuição à coesão do solo da raiz do capim-vetiver (Chrysopogon zizanioides (L.) Roberty), na estabilidade do talude para controle da erosão da margem direita do Rio São Francisco. Mudas do capim-vetiver foram plantadas no talude da margem direita do Baixo São Francisco no estado de Sergipe, com amostragem das plantas realizada após dois anos do plantio, a fim de avaliar o efeito da gramínea no aumento da resistência ao cisalhamento do solo. Foram utilizadas a metodologia do monólito e o método do cilindro para coleta de raiz, visando à avaliação da Densidade Radicular (DR), Densidade do Comprimento Radicular (DCR), Razão de Raiz por Área (RAR), Resistência de Raízes à Ruptura (TR) e Coesão da Raiz (CR). Os dados foram submetidos à análise de variância (p 0,05), com análise de regressão polinomial. Os resultados mostram que para DR, DCR e RAR, na camada de 0-0,10 m apresentaram valores mais altos de 4,84 kg m-3, 12,45 km m-3, 1,66%, respectivamente. O TR médio foi de 83 MPa e o CR de 528 kPa. O vetiver favorece o aumento da resistência ao...