Acessibilidade / Reportar erro

Estimation of water erosion rates in Espírito Santo state, Brazil1 1 Research work presented at the Universidade Federal de Alfenas/UNIFAL as part of the first author's dissertation

ABSTRACT

Water erosion is a natural geological process that is common in tropical regions. It is important to monitor it to contain its physical, environmental, and socio-economic impacts. In the Espírito Santo state, Brazil, much of the land is used for agriculture and studies related to water erosion are scarce. The spatial modeling of water erosion is useful for proposing mitigating measures because combining it with data from geographic information systems can identify the areas most prone to soil loss. The Revised Universal Soil Loss Equation - RUSLE, is a model that requires little input data and is easy to use, providing results useful of helping to mitigate water erosion and promote sustainable land use planning. This study estimates the water erosion rates in the Espírito Santo state by RUSLE and compares them with the soil loss tolerance (T) limits. The parameters used in the model are the land use and management, the soil attributes, the relief and the climate factors. Approximately 38.65% of the state’s area shows soil loss above the T limit (7.79 - 14.14 Mg ha-1 year-1). The areas with steeper slopes and low vegetation cover have most of the highest erosion rates. The mean annual soil loss of the entire state is 33.55 Mg ha-1 year-1. RUSLE provided a diagnosis useful of directing erosion mitigation measures to the most susceptible areas, enabling sustainable planning to support the state's socio-economic development.

Key words
Modeling; RUSLE; Soil conservation

INTRODUCTION

Approximately 70% of the territory of Espírito Santo state, Brazil, is covered by pasture, temporary and permanent crops or planted forest (MAPBIOMAS PROJECT, 2019MAPBIOMAS PROJECT. Coleção 5 da Série Anual de Mapas de Cobertura e Uso de Solo do Brasil. 2019. Disponível em: http://plataforma.mapbiomas.org/map#coverage. Acesso em: 14 jan. 2021.
http://plataforma.mapbiomas.org/map#cove...
). Water erosion is a common problem in these areas, especially in regions with more pronounced slopes. In addition, the conversion of natural vegetation into agricultural systems and their exploitation beyond the soil recovery capacity have contributed to increased soil loss rates.

In Brazil, the cost of soil erosion related to the loss of nutrients such as P, K+, Ca+, and Mg+ in annual crops is approximately US $ 1.3 billion annually (DECHEN et al., 2015DECHEN, S. C. F. et al. Perdas e custos associados à erosão hídrica em função de taxas de cobertura do solo. Bragantia, v. 74, n. 2, p. 224-233, 2015. DOI: https://doi.org/10.1590/1678-4499.0363.
https://doi.org/10.1590/1678-4499.0363...
). By reducing the availability of fertile soils, the sustainability of agricultural systems is compromised by the increased soil losses from erosion. The consequences of erosion can affect local and regional hydrological processes, change sediment flows, and even affect climate patterns (DOTTERWEICH, 2013DOTTERWEICH, M. The history of human-induced soil erosion: geomorphic legacies, early descriptions and research, and the development of soil conservation: a global synopsis. Geomorphology. v. 201, n. 1, p. 1-34, 2013. DOI: https://doi.org/10.1016/j.geomorph.2013.07.021.
https://doi.org/10.1016/j.geomorph.2013....
).

Thus, the adoption of predictive technologies, such as water erosion modeling, can help in the adoption of sustainable agricultural practices. In some European countries, the modeling of water erosion over large areas contributes to the proposition and adoption of environmental and agricultural policies to reduce the negative impacts of erosion (ALEWELL et al., 2019ALEWELL, C. et al. Using the USLE: chances, challenges and limitations of soil erosion modelling. International Soil and Water Conservation Research, v. 7, n. 3, p. 203-225, 2019. DOI: https://doi.org/10.1016/j.iswcr.2019.05.004.
https://doi.org/10.1016/j.iswcr.2019.05....
). In Brazil, despite the many studies on the deleterious effects of water erosion (BATISTA et al., 2017BATISTA, P. V. G. et al. Modeling spatially distributed soil losses and sediment yield in the upper Grande River Basin - Brazil. Catena, v. 157, n. 1, p. 139-150, 2017. DOI: https://doi.org/10.1016/j.catena.2017.05.025.
https://doi.org/10.1016/j.catena.2017.05...
; LENSE et al., 2021LENSE, G. H. E. et al. Soil losses in the State of Rondônia, Brazil. Ciência Rural, v. 51, n. 5, e20200460, 2021. DOI: https://doi.org/10.1590/0103-8478cr20200460.
https://doi.org/10.1590/0103-8478cr20200...
; MEDEIROS et al., 2016MEDEIROS, G. O. R. et al. Estimates of Annual Soil Loss Rates in the State of São Paulo, Brazil. Revista Brasileira de Ciência do Solo, v. 40, e0150497, 2016. DOI: https://doi.org/10.1590/18069657rbcs20150497.
https://doi.org/10.1590/18069657rbcs2015...
; STEINMETZ et al., 2018STEINMETZ, A. A. et al. Assessment of soil loss vulnerability in data-scarce watersheds in southern Brazil. Ciência e Agrotecnologia, v. 42, n. 6, p. 575-587, 2018. DOI: https://doi.org/10.1590/1413-70542018426022818.
https://doi.org/10.1590/1413-70542018426...
), their findings are still unknown and little used by farmers, authorities, or government agencies. This, despite the usefulness of water erosion estimates for the formulation of sustainable management planning policies and the implementation of soil conservation practices.

The Revised Universal Soil Loss Equation - RUSLE (RENARD et al., 1997RENARD, K. G. et al. Predicting soil erosion by water: a guide to conservation planning with the Revised Universal Soil Loss Equation (RUSLE). Washington, USA: United States Department of Agriculture, 1997. 384 p. (Agriculture Handbook, n. 703).) is a model used worldwide to estimate erosion rates (OLIVEIRA; SERAPHIM; BORJA, 2015OLIVEIRA, F. G.; SERAPHIM, O. J.; BORJA, M. E. L. Estimativa de Perdas de Solo e do Potencial Natural de Erosão da Bacia de Contribuição da Microcentral Hidrelétrica do Lageado, Botucatu - SP. Energia na Agricultura, v. 30, n. 3, p. 302-309, 2015. DOI: https://doi.org/10.17224/EnergAgric.2015v30n3p302-309.
https://doi.org/10.17224/EnergAgric.2015...
; PANAGOS et al., 2015PANAGOS, P. et al. Estimating the soil erosion cover-management factor at the European scale. Land Use Policy, v. 48, p. 38-50, 2015. DOI: https://doi.org/10.1016/j.landusepol.2015.05.021.
https://doi.org/10.1016/j.landusepol.201...
). A distinctive characteristic of RUSLE is the need for little input data, overcoming the lack of climatic and geographic information in some regions (BHANDARI; ARYAL; DARNSAWASDI, 2015BHANDARI, K. P.; ARYAL, J.; DARNSAWASDI, R. A geospatial approach to assessing soil erosion in a watershed by integrating socio-economic determinants and the RUSLE model. Natural Hazards, v. 75, n. 1, p. 321-342, 2015. DOI: https://doi.org/10.1007/s11069-014-1321-2.
https://doi.org/10.1007/s11069-014-1321-...
). After estimating soil losses by RUSLE, especially over large areas, geographic information systems enable the spatialization of the results (GANASRI; RAMESH, 2016GANASRI, B. P.; RAMESH, H. Assessment of soil erosion by RUSLE model using remote sensing and GIS: a case study of Nethravathi Basin. Geoscience Frontiers, v. 7, n. 6, p. 953-961, 2016. DOI: https://doi.org/10.1016/j.gsf.2015.10.007.
https://doi.org/10.1016/j.gsf.2015.10.00...
). The main limitation of the application of the RUSLE model is the fact that this model was developed for temperate edaphoclimatic conditions, different from the Brazilian tropical edaphoclimatic conditions (AMORIM et al., 2010AMORIM, R. S. S. et al. Avaliação do desempenho dos modelos de predição da erosão hídrica USLE, RUSLE e WEPP para diferentes condições edafoclimáticas do Brasil. Engenharia Agrícola, v. 30, n. 6, p. 1046-1049, 2010. DOI: https://doi.org/10.1590/S0100-69162010000600006.
https://doi.org/10.1590/S0100-6916201000...
). Despite these differences, this limitation has been overcome due to several works applying RUSLE in Brazilian soils, where the model parameters are constantly adapted to tropical climatic conditions (BATISTA et al., 2017BATISTA, P. V. G. et al. Modeling spatially distributed soil losses and sediment yield in the upper Grande River Basin - Brazil. Catena, v. 157, n. 1, p. 139-150, 2017. DOI: https://doi.org/10.1016/j.catena.2017.05.025.
https://doi.org/10.1016/j.catena.2017.05...
; DECHEN et al., 2015DECHEN, S. C. F. et al. Perdas e custos associados à erosão hídrica em função de taxas de cobertura do solo. Bragantia, v. 74, n. 2, p. 224-233, 2015. DOI: https://doi.org/10.1590/1678-4499.0363.
https://doi.org/10.1590/1678-4499.0363...
; MANNIGEL et al., 2002MANNIGEL, A. R. et al. Fator erodibilidade e tolerância de perda dos solos do Estado de São Paulo. Acta Scientiarum, v. 24, n. 5, p. 1335-1340, 2002. DOI: https://doi.org/10.4025/actasciagron.v24i0.2374.
https://doi.org/10.4025/actasciagron.v24...
; MARTINS et al., 2010MARTINS, S. G. et al. Fator cobertura e manejo do solo e perdas de solo e água em cultivo de eucalipto e em Mata Atlântica nos Tabuleiros Costeiros do Estado do Espírito Santo. Scientia Forestalis, v. 38, n. 87, p. 517-526, 2010.; MELLO et al., 2013MELLO, C. R. et al. Multivariate models for annual rainfall erosivity in Brazil. Geoderma, v. 203, n. 1, p. 88-102, 2013. DOI: https://doi.org/10.1016/j.geoderma.2013.03.009.
https://doi.org/10.1016/j.geoderma.2013....
).

The results of soil loss rate estimates can be compared to soil loss tolerance (T) limits (WISCHMEIER; SMITH, 1978WISCHMEIER, W. H.; SMITH, D. D. Predicting rainfall erosion losses: a guide to conservation planning. Washington, USA: United States Department of Agriculture, 1978. 58 p. (Agriculture Handbook, n. 537).). The T-index suggests the rate of erosion that a soil can withstand without compromising its productive capacity. The values found for T are highly important for decision-making for the control of water erosion. Although in the short term it is possible to use T values as an index of soil sustainability, in the long term, the erosion rates should tend to zero for the productive capacity of arable land to be sustainable (MENDES JÚNIOR et al., 2018MENDES JÚNIOR., H. et al. Water erosion in Oxisols under coffee cultivation. Revista Brasileira de Ciência do Solo, v. 42, n. 1, p. 70-84, 2018. DOI: https://doi.org/10.1590/18069657rbcs20170093.
https://doi.org/10.1590/18069657rbcs2017...
).

This study estimates the rates of soil loss due to water erosion in the Espírito Santo state using the RUSLE and compares them to the T.

MATERIAL AND METHODS

Study site

The study was conducted in the Espírito Santo state, located in the Southeast region of Brazil, between latitudes 17° 53′ and 21° 17′ S and longitudes 39° 39′ and 41° 52′ W, Datum SIRGAS 2000 (Figure 1). The state has 46,184.1 km2.

Figure 1
Location and climate map of the Espírito Santo state, Brazil, according to the Köppen climate classification

Because it is located in a coastal region of Southeast Brazil, the general climatic characteristic of the Espírito Santo state is a warm and rainy tropical regime, with no defined cold season. According to Alvares et al. (2013)ALVARES, C. A. et al. Köppen’s climate classification map for Brazil. Meteorologische Zeitschrift, v. 22, n. 6, p. 711-728, 2013. DOI: https://doi.org/10.1127/0941-2948/2013/0507.
https://doi.org/10.1127/0941-2948/2013/0...
, who applied the Köppen system to classify this state, most of the state has an Aw (tropical savanna) climate (Figure 1). The mean temperatures in the state vary between 22 and 24 °C, and the annual rainfall volume is greater than 1,400 mm, which is especially concentrated in the summer (ALVARES et al., 2013ALVARES, C. A. et al. Köppen’s climate classification map for Brazil. Meteorologische Zeitschrift, v. 22, n. 6, p. 711-728, 2013. DOI: https://doi.org/10.1127/0941-2948/2013/0507.
https://doi.org/10.1127/0941-2948/2013/0...
).

The land use map (Figure 2), which was extracted from the digital platform of the Mapbiomas Project (2019)MAPBIOMAS PROJECT. Coleção 5 da Série Anual de Mapas de Cobertura e Uso de Solo do Brasil. 2019. Disponível em: http://plataforma.mapbiomas.org/map#coverage. Acesso em: 14 jan. 2021.
http://plataforma.mapbiomas.org/map#cove...
, indicates that the main land-use classes in the Espírito Santo state are pasture (39.12%), followed by native forest (24.60%), temporary crops (18.65%), and permanent crops (8.30%). In addition, areas of planted forest (5.64%), urban infrastructure (1.38%), water bodies (1.03%), rocky outcrops (0.70%), other natural formations (0.18%), non-vegetated areas (0.17%), mangrove areas (0.14%), and beaches and dunes (0.09%). The planted forest use class consists mainly of eucalyptus plantations.

Figure 2
Land use map of the Espírito Santo state, Brazil

Latosols are the main soil class of Espírito Santo (49.71%), followed by Argisols (25.50%) and Cambisols (12.00%). The other soil classes are Neosols (4.13%), Gleysols (2.70%), Nitosols (2.30%), Charmosos (0.93%), Spodosols (0.85%) and Indiscriminate Mangrove Soils (0.15%). There are also rocky outcrops (0.70%). Figure 3 shows the soil map of the Espírito Santo state, scale 1:250,000 (CUNHA et al., 2016CUNHA, A. M. et al. Atualização da legenda do mapa de reconhecimento de solos do Estado do Espírito Santo e implementação de interface no geobases para uso dos dados em SIG. Revista do Programa de Pós-Graduação em Geografia e do Departamento de Geografia da UFES, v. 2, n. 22, p. 32-65, 2016. DOI: https://doi.org/10.47456/geo.v2i22.30205.
https://doi.org/10.47456/geo.v2i22.30205...
).

Figure 3
Soil map of the Espírito Santo state, Brazil

The average altitude of the state of Espírito Santo varies between 650 and 750 m, and its highest altitude, in Serra do Caparaó, is Pico da Bandeira, with 2,892 m (Figure 4A). The Shuttle Radar Topography Mission digital elevation model (DEM), with 30 m spatial resolution, was extracted from the Brasil em Relevo digital platform, of the Empresa Brasileira de Pesquisa Agropecuária - EMBRAPA (MIRANDA, 2005MIRANDA, E. E. Brasil em relevo. Campinas: Embrapa Monitoramento por Satélite, 2005. Disponível em: http://www.relevobr.cnpm.embrapa.br. Acesso em: 14 jan. 2021.
http://www.relevobr.cnpm.embrapa.br...
). The slope map (Figure 4B) was generated from the DEM using the Slope tool in ArcMap 10.5 (ENVIRONMENTAL SYSTEMS RESEARCH INSTITUTE, 2017ENVIRONMENTAL SYSTEMS RESEARCH INSTITUTE. ARCGIS Professional GIS for the desktop version 10.5. Redlands, California: ESRI, 2017.). In Espírito Santo, reliefs with slopes between 8-20% and 20-45% predominate, representing 28% and 30% of the state, respectively.

Figure 4
Digital elevation model (A) and declivity map (B) of the Espírito Santo state, Brazil

Revised Universal Soil Loss Equation

The RUSLE model is represented by Equation 1.

(1) A = R × K × L S × C × P

Where: A is the mean annual soil loss, in Mg ha-1 year-1; R is the rainfall erosivity factor, in MJ mm ha-1 h-1 year-1; K is the soil erodibility factor, in Mg ha-1 MJ-1 mm-1; LS is the topographic factor, dimensionless; C is the land use and management factor, dimensionless; and P is the conservation practices factor, dimensionless.

The R factor reflects the action of rain on soil water erosion. The R factor was determined based on the results of Saito et al. (2009)SAITO, N. S. et al. Uso da Geotecnologia na estimativa da erosividade das chuvas e sua relação com o uso e ocupação do solo para o Espírito Santo. Revista Verde de Agroecologia e Desenvolvimento Sustentável, v. 4, n. 2, p. 51-63, 2009., who calculated the mean annual erosivity for Espírito Santo from 88 rainfall stations distributed in the state. The K factor reflects the susceptibility of each soil to water erosion. This parameter varies according to the soil characteristics, and the higher it is, the more susceptible the soil is to erosion. For each of the main soil classes, a K value was assigned based on Silva and Alvares (2005)SILVA, A. M.; ALVARES, C. A. Levantamento de informações e estruturação de um banco de dados sobre a erodibilidade de classes de solos no Estado de São Paulo. Geociências, v. 24, n. 1, p. 33-42, 2005. (Table 1).

Table 1
K factor values for the soils of the Espírito Santo state, Brazil

The LS factor represents the effect of relief on soil loss rates. To calculate this parameter, the method of Moore and Burch (1986)MOORE, I. D.; BURCH, G. J. Physical basis of the length slope factor in the Universal Soil Loss Equation. Soil Science Society of America Journal, v. 50, n. 5, p. 1294-1298, 1986. DOI: https://doi.org/10.2136/sssaj1986.03615995005000050042x.
https://doi.org/10.2136/sssaj1986.036159...
was used, which is based on the DEM (Equation 2):

(2) L S = ( F A 30 22.13 ) 0.4 × ( sin ( S ) 0.0896 ) 1.3

Where LS is the topographic factor, dimensionless; FA is the flow accumulation expressed as the number of cells in the DEM grid; S is the slope of the relief in degrees; and 30 is the spatial resolution of the DEM in meters.

The LS parameter was calculated using the Raster Calculator tool in ArcMap 10.5 (ENVIRONMENTAL SYSTEMS RESEARCH INSTITUTE, 2017ENVIRONMENTAL SYSTEMS RESEARCH INSTITUTE. ARCGIS Professional GIS for the desktop version 10.5. Redlands, California: ESRI, 2017.).

Factor C represents the protection of the soil vegetation cover against the erosion process. This factor has higher values in areas with lower plant density and lower values in areas with good vegetation cover. In Espírito Santo, the C factor was obtained from values available in the scientific literature (Table 2). The P factor varies from close to 0 to 1, according to the presence or absence of soil conservation management practices. The parameter was determined according to the values reported by Bertoni and Lombardi Neto (2017)BERTONI, J.; LOMBARDI NETO, F. Conservação do solo. 10. ed. São Paulo: Ícone, 2017. 392 p. (Table 2).

Table 2
Values of factors C and P for the land use classes of the Espírito Santo state, Brazil

All parameters of the RUSLE model were converted to raster data format and multiplied among themselves in the Raster Calculator tool in ArcMap 10.5 (ENVIRONMENTAL SYSTEMS RESEARCH INSTITUTE, 2017ENVIRONMENTAL SYSTEMS RESEARCH INSTITUTE. ARCGIS Professional GIS for the desktop version 10.5. Redlands, California: ESRI, 2017.), which generated the spatialization of the results.

The soil losses calculated for Espírito Santo state were compared with the T limits of each soil class, as shown in Table 3.

Table 3
Soil loss tolerance (T) limits for the soils of the Espírito Santo state, Brazil

RESULTS AND DISCUSSION

The erosivity for Espírito Santo state varied between 4,843 and 7,783 MJ mm ha-1 h-1 year-1 (Figure 5A), with a mean of 6,012 MJ mm ha-1 h-1 year-1, which agrees with the values obtained by Mello et al. (2013)MELLO, C. R. et al. Multivariate models for annual rainfall erosivity in Brazil. Geoderma, v. 203, n. 1, p. 88-102, 2013. DOI: https://doi.org/10.1016/j.geoderma.2013.03.009.
https://doi.org/10.1016/j.geoderma.2013....
. The classification by these authors ranks the erosivity of the state as “very strong” due to its high rainfall index, especially in the central and south mesoregions. The geographic location of the state is one factor that explains the high rainfall: it is coastal and more likely to receive rain from the ocean. In addition, the greater erosivity of some points is related to their higher altitude, indicating areas of more intense rainfall.

Figure 5
Spatial distribution of rainfall erosivity - R (A) and topographic factor - LS (B) for the Espírito Santo state, Brazil

For the LS factor, an average of 4.6 was obtained (Figure 5B). The map indicates that the regions with LS factors below 2 are concentrated mainly on the coast, where the gentlest slopes are found. On the other hand, in 24.85% of the state, the LS was greater than 10, indicating that these areas are highly vulnerable to water erosion. These sites lack incentives for stakeholders to establish soil conservation practices to reduce runoff energy due to topography (BATISTA et al., 2017BATISTA, P. V. G. et al. Modeling spatially distributed soil losses and sediment yield in the upper Grande River Basin - Brazil. Catena, v. 157, n. 1, p. 139-150, 2017. DOI: https://doi.org/10.1016/j.catena.2017.05.025.
https://doi.org/10.1016/j.catena.2017.05...
; STEINMETZ et al., 2018STEINMETZ, A. A. et al. Assessment of soil loss vulnerability in data-scarce watersheds in southern Brazil. Ciência e Agrotecnologia, v. 42, n. 6, p. 575-587, 2018. DOI: https://doi.org/10.1590/1413-70542018426022818.
https://doi.org/10.1590/1413-70542018426...
).

The total soil loss in the Espírito Santo state was approximately 150 million tons per year, with an estimated mean of 33.55 Mg ha-1 year-1. The spatialization of losses calculated by RUSLE is illustrated in Figure 6.

Figure 6
Spatial distribution of soil losses of the Espírito Santo state, Brazil

The highest soil losses were recorded in nonvegetated areas (137.05 Mg ha-1 year-1), in annual crops (97.50 Mg ha-1 year-1), and in planted forests (73.00 Mg ha-1 year-1), while the lowest losses were estimated for native forests (2.65 Mg ha-1 year-1) and other natural formations (1.58 Mg ha-1 year-1). Permanent crops had lower soil loss values (18.20 Mg ha-1 year-1) than temporary crops because permanent crop soil is not turned or exposed as often as temporary crop soil is. In pasture areas, soil losses were 22.64 Mg ha-1 year-1.

The average soil losses estimated for the state of Espírito Santo (33.55 Mg ha-1 year-1) were very close to those reported by Medeiros et al. (2016)MEDEIROS, G. O. R. et al. Estimates of Annual Soil Loss Rates in the State of São Paulo, Brazil. Revista Brasileira de Ciência do Solo, v. 40, e0150497, 2016. DOI: https://doi.org/10.1590/18069657rbcs20150497.
https://doi.org/10.1590/18069657rbcs2015...
, for the state of São Paulo, with an average soil loss rate of 30 Mg ha-1 year-1. However, higher than those of Lense et al. (2021)LENSE, G. H. E. et al. Soil losses in the State of Rondônia, Brazil. Ciência Rural, v. 51, n. 5, e20200460, 2021. DOI: https://doi.org/10.1590/0103-8478cr20200460.
https://doi.org/10.1590/0103-8478cr20200...
for the state of Rondônia, with an average soil loss of 22.5 Mg ha-1 year-1, due to the greater areal coverage of the Amazon biome.

Espírito Santo has a percentage of 38.65% of its area with soil losses above the limits of T. These areas must be prioritized for the implementation of conservation practices to mitigate erosion. In addition, these sites with losses above the T limits are distributed throughout the state (Figure 7), demonstrating the need to define a comprehensive management plan to reduce water erosion.

Figure 7
Priority areas for conservation management of the Espírito Santo state, Brazil

As Espírito Santo has large areas covered by soils with high erosion susceptibility (Argisols and Cambisols, respectively, 25.50% and 12.00%), special attention should be given to the management of these soils, since when associated with uses with little or no vegetation cover, soil loss values higher than the T limits are reached (LENSE et al., 2021LENSE, G. H. E. et al. Soil losses in the State of Rondônia, Brazil. Ciência Rural, v. 51, n. 5, e20200460, 2021. DOI: https://doi.org/10.1590/0103-8478cr20200460.
https://doi.org/10.1590/0103-8478cr20200...
).

Latosols occupy about 50% of the state and, although they have greater resistance to water erosion, when associated with agricultural crops under inadequate management, they present significant losses and compromise soil sustainability. Mainly in areas with steeper slopes, indicating the importance of vegetation cover and management practices in reducing erosion rates (LENSE et al., 2020LENSE, G. H. E. et al. Simulating the effect of Permanent Preservation Areas on soil erosion rates. CERNE, v. 26, n. 2, p. 193-201, 2020. DOI: https://doi.org/10.1590/01047760202026022692.
https://doi.org/10.1590/0104776020202602...
).

The regions with high erosivity and higher LS factor values show that the different soil classes are subject to high water erosion rates. Thus, management practices, changes in land use, and vegetation cover maintenance play important roles in reducing erosion rates, especially in the soil classes most vulnerable to water erosion (LENSE et al., 2020LENSE, G. H. E. et al. Simulating the effect of Permanent Preservation Areas on soil erosion rates. CERNE, v. 26, n. 2, p. 193-201, 2020. DOI: https://doi.org/10.1590/01047760202026022692.
https://doi.org/10.1590/0104776020202602...
, 2021; MEDEIROS et al., 2016MEDEIROS, G. O. R. et al. Estimates of Annual Soil Loss Rates in the State of São Paulo, Brazil. Revista Brasileira de Ciência do Solo, v. 40, e0150497, 2016. DOI: https://doi.org/10.1590/18069657rbcs20150497.
https://doi.org/10.1590/18069657rbcs2015...
; STEINMETZ et al., 2018STEINMETZ, A. A. et al. Assessment of soil loss vulnerability in data-scarce watersheds in southern Brazil. Ciência e Agrotecnologia, v. 42, n. 6, p. 575-587, 2018. DOI: https://doi.org/10.1590/1413-70542018426022818.
https://doi.org/10.1590/1413-70542018426...
). These results reveal the need for planning, implementation, and dissemination of more effective soil management techniques and conservation practices for agricultural and pasture areas, and for reducing areas with exposed soil, in order to minimize the number of sites with erosion rates higher than the T limits.

Public policies should be formulated based on the results of the spatialization of soil losses to adjust land use according to agricultural suitability, especially in areas with high erosion rates (MEDEIROS et al., 2016MEDEIROS, G. O. R. et al. Estimates of Annual Soil Loss Rates in the State of São Paulo, Brazil. Revista Brasileira de Ciência do Solo, v. 40, e0150497, 2016. DOI: https://doi.org/10.1590/18069657rbcs20150497.
https://doi.org/10.1590/18069657rbcs2015...
). Coordinated legislation should permeate the different hierarchical levels of public administration, from municipal to state, and should extend to partnerships with the federal government to popularize conservation practices and establish public policies that drive the sustainable use of soils based on their vulnerability to erosion (ALEWELL et al., 2019ALEWELL, C. et al. Using the USLE: chances, challenges and limitations of soil erosion modelling. International Soil and Water Conservation Research, v. 7, n. 3, p. 203-225, 2019. DOI: https://doi.org/10.1016/j.iswcr.2019.05.004.
https://doi.org/10.1016/j.iswcr.2019.05....
; LENSE et al., 2021LENSE, G. H. E. et al. Soil losses in the State of Rondônia, Brazil. Ciência Rural, v. 51, n. 5, e20200460, 2021. DOI: https://doi.org/10.1590/0103-8478cr20200460.
https://doi.org/10.1590/0103-8478cr20200...
).

With the provision of information on sustainable land use techniques, the interaction of the people with these data favors a scenario in which economic and social development coexist with respect of the environment, and such practices will tend to become permanent over time through the cultural habits of successive generations. It is important to apply the knowledge acquired through geographic and soil sciences as a development tool in a society in which these practices were previously uncommon.

CONCLUSIONS

  1. The Espírito Santo state has high erosivity indices, steep reliefs, and soils with high vulnerability to erosion processes. Thus, plant cover and soil management practices will play an essential role in reducing soil losses in the region;

  2. RUSLE estimates a mean soil loss of 33.55 Mg ha-1 year-1, and in 38.65% of the Espírito Santo state, the erosion rates are above the soil loss tolerance limits. These areas should be prioritized in the adoption of mitigation measures to reduce water erosion;

  3. The results of this study may contribute to the development of different soil management and conservation planning scenarios and may help in developing public policies that encourage conservation and sustainable land use in the Espírito Santo state.

ACKNOWLEDGMENTS

We are especially thankful to the Fundação de Amparo à Pesquisa do Estado de Minas Gerais - FAPEMIG, for the scholarships granted to the first and second authors. This study was funded in part by the “Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil” (CAPES) - Finance Code 001.

  • 1
    Research work presented at the Universidade Federal de Alfenas/UNIFAL as part of the first author's dissertation

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Edited by

Editor-in-Chief: Profa. Riselane de lucena alcântara bruno Riselane Bruno - lanebruno.bruno@gmail.com

Publication Dates

  • Publication in this collection
    14 Aug 2023
  • Date of issue
    2023

History

  • Received
    07 June 2021
  • Accepted
    08 Mar 2023
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