Efecto Del Cambio De Uso en La Estabilidad De La Estructura Y La Función De Los Poros De Un Andisol (Typic Hapludand) Del Sur De Chile

Abstract

Volcanic soils in southern Chile cover approximately 60% of the arable land in the country. These soils are under a wide range of land uses from pristine systems to intensively used ones. The objective of this study was to determine the effect of the land use change on: i) the structural stability after external and internal forces, ii) the hydraulic conductivity and iii) its functional resilience. Disturbed and undisturbed soil samples were collected at 5, 20 and 40 cm depths in an Andisol (Typic Hapludand) under native forest (NF), 50 year old pasture (P50) and 1 year old pasture (P1). The water retention, shrinkage and consolidation curves, hydraulic conductivity (Ks), air permeability (Ka), organic carbon content (CO), soil texture and allophane contents were determined. The unsaturated hydraulic conductivity (Ku) was estimated according to van Genuchten (1980). Soil deformation indexes as a consequence of mechanical (COLEm) and hydraulic (COLE h ) stresses were calculated. The studied soil is subject to continuous changes in their structure as a consequence of mechanical and hydraulic stresses affecting the pore size distribution and its functionality. The magnitude of these changes decreased with the increasing intensity of the land use. The great shrinkage capacity of the soil may have consequences on its hydraulic behaviour depending on the drying intensity through the formation of cracks and preferential path flows. Finally, the soil pores are able to recover its functional integrity after compaction, which is strongly related to the presence of organic matter contents.Keywords: Andisol, structural properties, pore functions RESUMENLos suelos volcánicos del sur de Chile constituyen cerca del 60% del suelo arable del país. Estos suelos se encuentran bajo un amplio rango de usos desde sistemas prístinos hasta otros con un uso intensivo. El objetivo de este trabajo fue determinar el efecto del cambio de uso de suelo sobre: i) la estabilidad del suelo frente a presiones externas e internas; ii) la conductividad hidráulica y iii) su resiliencia funcional. Muestras disturbadas y no disturbadas de suelo fueron recolectadas a 5, 20, 40 cm de profundidad 190 Rev. Cienc. Suelo Nutr. / J. Soil. Sci. Plant Nutr. 9(3): 190-209 (2009)

Effect of land use change on the dynamic behaviour of structural properties of an Andisol in southern Chile under saturated and unsaturated hydraulic conditions

“…The soil reached moisture ratios near saturation after 3 rainfall events of 40, 70 and 51 mm on August 7th and 13th and September 3rd, respectively. These values, however, decreased quickly after the rainfall because of the great hydraulic conductivity of these soils (Dörner et al, 2009b), particularly in NF. During the rainy season, moisture and void ratios did not exceed the structural shrinkage point (ϑ shw and e shw ), i.e.…”

Resiliência física de dois latossolos vermelhos sob plantio direto

“…Esse impacto causado pelos ciclos de umedecimento e secamento, ou seja, dependendo das alterações no conteúdo de água no solo, aliado ao manejo, faz com que a estrutura do solo, bem como suas propriedades relacionadas ao sistema poroso, como índice de vazios (Dörner et al, 2009), capacidade de aeração, condutividade hidráulica e resistência a penetração , apresentem comportamento dinâmico e mudem temporária e espacialmente.…”

“…Essa quantificação que relaciona o impacto do manejo sobre as funções dos poros do solo e a sua capacidade para se recuperar (Peth & Horn, 2006;Gregory et al, 2007Gregory et al, , 2009Dörner et al, 2009) vem, segundo Dörner et al (2011), de encontro às prioridades atuais, como a melhoria na qualidade dos solos para aumento da produção de alimentos, o controle de tráfego devido ao aumento do peso das máquinas, o qual sujeita o solo a maiores estresses mecânicos, e a exposição do solo à seca em muitas áreas devido à mudança do clima, principalmente nos trópicos e subtrópicos, onde o risco de degradação do solo é um problema severo e são raras as informações em relação à recuperação de áreas degradadas e ao impacto econômico na produção (Blanco & Lal, 2010). CONCLUSÕES 1.…”

Functional resistance and resilience of the pore system of an andisol exposed to different strategies of pasture improvement under sheep grazing

“…The drying of the soil is one of the most common stresses that can affect an agro-ecosystem and is currently of great importance, because the soil as a resource will be exposed to higher hydraulic stresses due to climate change and land use change (Dörner et al, 2009a). In the case of air capacity (AC, Figure 1c), in most observed cases there was an increase in the level of this parameter (all above the critical level), although not significantly.…”

“…animal trampling, traffic of heavy machines) has been reported in Andisols of Chile (Dörner et al, 2009a(Dörner et al, , b, 2011. The same effect was reported on Calcic…”