A Comparative Analysis of Soil Loss Tolerance and Productivity of the Olive Groves in the Protected Designation of Origin (PDO) Areas Norte Alentejano (Portugal) and Estepa (Andalusia, Spain)

Olive groves are Mediterranean systems that occupy more than 2.5 M ha in Spain and 0.352 M ha in Portugal. Assuming the differences between both countries in terms of olive grove regulation and considering their multifunctionality, it is useful to implement agronomic indices to estimate their sustainability. The Soil Loss Tolerance Index (SLTI) and the Soil Productivity Index (SPI) are two such indices. We calculated both indices in the Protected Designation of Origin (PDO) Norte Alentejano (Portugal). The SLTI index was adapted considering specific variables of the analysed olive groves (i.e., SLTIog). The values obtained were compared with those previously estimated for PDO Estepa (Spain). The negative impacts of erosion and the underlying agricultural practices on the sustainability of olive groves became evident, resulting in decreased soil productivity at the regional level. The SLTIog index showed higher values for crops, being a more realistic tool to analyse sustainability. A higher soil loss tolerance was detected for integrated groves in the PDO Norte Alentejano than for PDO Estepa due to the shorter age of olive cultivation in Portugal, with incipient soil impacts. These indices provide information on the degree of soil erosion, allowing farmers and decision-makers to apply practices to maximise the sustainability of olive groves.

Assessment of the spatial distribution of global soil loss tolerance by using the productivity index method

<p>The soil loss tolerance (T value) is the ultimate criterion for determining whether a soil has potential erosion risks. While the existing T value criteria are mainly on national scale, and lack of consideration of the differences in soil erosion, soil properties and soil productivity between different types of land use. We calculated the global T value by using the productivity index method. The global T values ranged from 0.84 to 4.99 Mg ha<sup>-1</sup> yr<sup>-1</sup>, with an average of 1.49 Mg ha<sup>-1</sup> yr<sup>-1</sup>. The distribution of T values in global scale demonstrated significant spatial differences, and the range of T values in most regions of the land (98.23%) was between 1.0 and 2.0 Mg ha<sup>-1</sup> yr<sup>-1</sup>. The mean T values varied from c ontinent to continent, with Africa and Oceania having higher mean T values than other continents. The T values between different land use types varied widely, and the T values of five land use types were as follows: cropland (1.67 Mg ha<sup>-1</sup> yr<sup>-1</sup>) > shrubland (1.61 Mg ha<sup>-1</sup> yr<sup>-1</sup>) > grassland (1.59 Mg ha<sup>-1</sup> yr<sup>-1</sup>) > forestland (1.38 Mg ha<sup>-1</sup> yr<sup>-1</sup>) > wetland (1.28 Mg ha<sup>-1</sup> yr<sup>-1</sup>).</p>

Assessment of Soil loss Tolerance limit to Latosol, Argisol and Cambisolin the southern Minas Gerais state

Soil Loss Tolerance (T) reflects the maximum erosion rate that still allows a sustainable level of crop production. The T limit can be used to support the conservationist land-use planning and to propose erosion mitigation measures. In this context, we aim to determine the Soil Loss Tolerance limit to different soil classes located at the Coroado Stream Subbasin, southern Minas Gerais, Brazil. The soil classes of the subbasin area was classified as Dystrophic Red Latosols - LVd (90.0%), Eutrophic Red-Yellow Argisols - PVAe (5.4%), and Dystrophic Tb Haplic Cambisols - CXbd (1.9%). The following attributes were used to determine the T limits: texture, depth, density, permeability, and organic matter. To analyzing these parameters, we collect soil samples at 18 points distributed along the subbasin area. T values ranged from 4.75 to 7.40 Mg ha-1 year-1, with the lowest limit observed for CXbd (4.75 Mg ha-1 year-1). These results indicate that the Cambisol should be prioritized in the adoption of conservation practices to reduce water erosion and to maintain soil loss levels at acceptable rates. Latosols, Argisols, and Cambisols are the most common soils in the Brazilian territory. Thus, the results provided by the work can be used as a reference to monitoring the erosion process and evaluate the sustainability of agricultural activities in Brazil.

Estimation of Soil Loss Tolerance in Olive Groves as an Indicator of Sustainability: The Case of the Estepa Region (Andalusia, Spain)

Spain is the world's leading producer of olive oil, with the largest number of olive agro-systems in the Andalusia region. However, rural migration, low profitability, and biophysical limitations to production have compromised their sustainability. Soil erosion is the main cause of declining production and must be controlled to sustain production and keep soil loss below a threshold (soil loss tolerance, SLT). In this paper, the Soil Loss Tolerance Index (SLTI) for non-specific crops was calculated, theoretically, in different Andalusian olive-growing areas. A new Soil Loss Tolerance Index specifically for olive groves was developed (SLTIog) using soil variables related to erosion corresponding to the Estepa region. This index and the Soil Productive Index (SPI) were estimated. Andalusian olive groves with severe erosion were unsustainable for a 150-year period according to SLTI. However, applying the SLTIog in olive groves of Estepa, soil loss was not unsustainable. Although no statistically significant differences were detected between the two SLT indices, the consideration of specific soil variables in the SLTIog made it more accurate and reliable for the assessment of potential long-term sustainability. The use of specific indices for olive groves can inform the adoption of management measures to maintain productivity and support conservation.

INTER-RELATIONSHIP BETWEEN ERODIBILITY, SOIL TOLERANCE AND PYSICAL-CHEMICAL ATTRIBUTES ON NORTHWEST OF SÃO PAULO STATE

Erosive processes are major environmental problems in soils and constitute a great conservation planning challenge. The knowledge of erodibility and soil loss tolerance, as well as their interactions with physical and chemical attributes of the soil may allow an important diagnostic for sustainable management. The aim of this study was to determine soil erodibility (K) and soil loss tolerance (T) for 32 kinds of soil in the Northwest Region of São Paulo State and assess the linear and spatial correlations between these factors and physical-chemical attributes. The evaluated attributes were: textural relationship (TR), particle density (PD), bulk density (BD), total porosity (TP), macro porosity (MA), micro porosity (MI), water capacity storage (WCS), organic matter (OM) and soil pH (pH). The results showed that K factor ranged from 0.0094 to 0.0758 Mg/ ha MJ mm, while T values ranged from 3.09 to 14.79 Mg /ha year. The erodibility and loss tolerance present significant interaction with the soil physical and chemical attributes, especially with the WCS and the TR that showed the best regression adjustments. In geostatistical point of view, the erodibility and soil loss tolerance also showed considerable spatial correlations with most soil physical properties, especially interactions with the TP and the TR, allowing the best mappings using cokriging technique. Thus, simple and relatively low cost approach preliminary soil erodibility can be adopted for large areas without complexes surveys and in situ tests. As well as long term climate data series, a common situation in large areas in less developed countries.

Estimates of soil losses by the erosion potential method in tropical latosols

ABSTRACT Water erosion is one of the main problems faced in coffee cultivation, as it promotes environmental degradation and crop yield decrease. Erosion estimates support the planning of conservation management practices and allowing determining the rates of soil losses. Thus, the objective of this paper was to estimate the soil loss by water erosion using the Erosion Potential Method in a sub-basin predominantly covered by coffee cultivation and then to compare the results with the Soil Loss Tolerance limits. The study area is the Coroado Stream Sub-basin, located at Alfenas Municipality, south of Minas Gerais, Brazil. The sub-basin presented an Erosion Coefficient of 0.272, indicating a predominance of low-intensity erosion. The total soil loss estimate was 1,772.01 Mg year-1 with an estimated average of 1.74 Mg ha-1 year-1. Soil Loss Tolerance limits range from 4.75 to 7.26 Mg ha-1 year-1 and, according to the Erosion Potential Method, only 1.0% of the sub-basin presented losses above the limits. The areas with the highest slopes and bare soil concentrated the highest losses rates and should be prioritized in the adoption of mitigation measures. The Erosion Potential Method estimated soil losses in tropical edaphoclimatic conditions in a fast, efficiently and at low cost, supporting the adoption of conservation management practices.

Estimation of soil erosion considering soil loss tolerance in karst area

The prediction of soil erosion is critical to regional ecological assessment and sustainable development. However, due to the geological background of the karst area, the soil holding capacity is very limited, so it is necessary to consider the allowable loss of soil. Here we took thermodynamic dissolution model of carbonate rocks and the lithological characteristics to estimate soil loss tolerance, and corrected and quantitatively evaluated the soil erosion. Major findings are as follows: (1) The soil loss tolerance of homogenous carbonate rocks is 31.10 t · ha · yr−1, carbonate rock intercalated with clastic rocks is 120.81 t · ha · yr−1, carbonate/clastic rock alternations is 282.55 t · h · yr−1, and clastic rock is 500 t · ha · yr−1. (2) After the correction of the soil loss tolerance, the average annual amount of soil loss in the study area is 3.08 t · ha · yr−1, which is 41.12 % of the model. The predicted value of soil erosion is nearly the same as the observed value after modification. (3) It is necessary to reconsider the risk assessment model of soil erosion applicable to karst areas. This paper proposes an idea to estimate soil erosion based on the allowable loss of soil, which is more scientifically and accurately to reflect the soil erosion status of the study area compared with the traditional way. This study provides a corresponding reference for the formulation of soil and water conservation policies in China and the world's karst regions.