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  • Gully Erosion Stabilization in a Highly Erodible Kandiustalf Soil at Pindorama, São Paulo State, Brazil
  • Maria Teresa Vilela Nogueira Abdo, Sidney Rosa Vieira, Antonio Lucio Mello Martins, and Luis Cláudio Paterno Silveira

Erosion and loss of topsoil are the greatest challenges for agricultural sustainability. The increase of degraded soil threatens the productivity of agriculture and agroindustry, therefore undermining socio-economic development. Soil erosion is primarily caused by unrestrained water flow. The loss of nutrients from topsoil decreases plant growth and soil productivity because sub-soils are generally less fertile. Agriculturally valuable soil stock is finite because top soils are not renewed as fast as they are degraded and eroded. Degradation of agricultural land threatens the sustainability of growth and welfare of many people around the world that depend on agriculture for their livelihoods (Pagiola 1999). In these areas, agriculture is unsustainable unless the soil is rehabilitated to reverse the degradation process. In the 1980s a new economic development concept arose, incorporating social and environmental preservation, and a new ideal emerged: sustainability, defined as a set of practices that involves resource management appropriate to satisfy human needs while maintaining or enhancing environmental quality and conserving natural resources. This new ideal involved no-tillage soil conservation practices, graded level terraces, and improving road levels to better conduct excess runoff (Vieira 1997).

Accelerated erosion is a result of human misuse of soil where the losses are no longer compensated by the geologic substrate or by alluvial contributions. Since 1945, an estimated two billion hectares of agricultural land, almost 18% of Earth's vegetated land, have been degraded as a result of a human activity and almost 11% of Earth's vegetated land has been degraded, significantly reducing productivity (Pagiola 1999). Gully erosion is responsible for many degraded areas and is very difficult to control. [End Page 246] Gullies can be branched, deep, present irregular walls, and present "U" transverse profiles. This form of erosion is the most complex and destructive, as it is the product of the combined action of superficial and underground runoff leading to a morpho-hydro-pedologic imbalance due to inappropriate use and occupation of the soil.

In Brazil, although there are no exact data, deforestation followed by inadequate agricultural activities are major degradation factors. In the São Domingos river watershed, in Pindorama, São Paulo state, Brazil, erosion susceptibility is mostly in the Classes I (very high) and II (high). This is a severely gully-eroded landscape in a Kandiustalf soil area, well drained, with average slopes from 2 to 10%. There are 50 years of accumulated data on erosion experiments at the Polo Regional Centro Norte, and some soil conservation practices have been specially developed to reduce erosion problems in the countryside and agricultural areas (Vieira et al. 1997). In this paper we report on the success of a gully erosion stabilization project started in 1997 to restore original water flow and stop erosion, resulting in the local sustainability of the soil, plant communities, and the reestablishment of native animal communities (Vieira et al. 1997, Abdo 1999).

This restoration took place at the Polo Regional Centro Norte-APTA research center, located in the municipality of Pindorama, São Paulo state, Brazil (21° 13' S; 48° 55' W). The entire reserve encompasses 532.8 ha, including native forest fragments that are considered a Biological Reserve under São Paulo state law 4960/86. The climate of this region, according to Köppen classification (Lepsch and Valadares 1976), is tropical and humid, with a dry season during winter and a rainy season during summer. The average annual rainfall is 1258 mm. The average temperature during the summer months is 23.8°C (January, February and March) and the average temperature during the winter months (June, July and August) is 19.3°C.

The native forest area (144 ha) is considered a conservation unit because it supports a diversity of regional endemic species and requires special management and protection. These forest fragments are classified as seasonal semi-deciduous tropical forest of the Atlantic Forest biome (Abdo 2009) and are very important for local floral and faunal diversity. In a tree survey of two toposequences, in two different fragments...

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