Conservation tillage and macropore factors that affect water movement and the fate of chemicals

Shipitalo, M. J.; Dick, Warren A.; Edwards, William M.

doi:10.1016/s0167-1987(99)00104-x

Cited by 235 publications

(136 citation statements)

References 55 publications

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“…Long-lasting soil structures generated by earthworms exert significant influence on process thresholds for overland flow and the initiation of rapid solute transport (Edwards et al, 1990a;Shipitalo and Butt, 1999;Shipitalo et al, 2000;Bastardie et al, 2002Bastardie et al, , 2003 and their spatial distribution affects connectivity of flow paths that determine response thresholds for overland flow at the catchment scales . Earthworm behaviour and their metabolic activity are also crucial for organic matter dynamics, pedogenetic processes, plant growth and degradation of herbicides Hedde et al, 2005;Milcu, 2005;Bolduan and Zehe, 2006;Milcu et al, 2006).…”

Section: Biological Controls Of Hydrological Functioning In Pristine mentioning

confidence: 99%

Threshold behaviour in hydrological systems as (human) geo-ecosystems: manifestations, controls, implications

Zehe¹,

Sivapalan

2009

Hydrol. Earth Syst. Sci.

196

139

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Abstract. In this paper we review threshold behaviour in environmental systems, which are often associated with the onset of floods, contamination and erosion events, and other degenerative processes. Key objectives of this review are to a) suggest indicators for detecting threshold behavior, b) discuss their implications for predictability, c) distinguish different forms of threshold behavior and their underlying controls, and d) hypothesise on possible reasons for why threshold behaviour might occur. Threshold behaviour involves a fast qualitative change of either a single process or the response of a system. For elementary phenomena this switch occurs when boundary conditions (e.g., energy inputs) or system states as expressed by dimensionless quantities (e.g. the Reynolds number) exceed threshold values. Mixing, water movement or depletion of thermodynamic gradients becomes much more efficient as a result. Intermittency is a very good indicator for detecting event scale threshold behavior in hydrological systems. Predictability of intermittent processes/system responses is inherently low for combinations of systems states and/or boundary conditions that push the system close to a threshold. Post hoc identification of "cause-effect relations" to explain when the system became critical is inherently difficult because of our limited ability to perform observations under controlled identical experimental conditions. In this review, we distinguish three forms of threshold behavior. The first one is threshold behavior at the Correspondence to: E. Zehe (e.zehe@bv.tum.de) process level that is controlled by the interplay of local soil characteristics and states, vegetation and the rainfall forcing. Overland flow formation, particle detachment and preferential flow are examples of this. The second form of threshold behaviour is the response of systems of intermediate complexity -e.g., catchment runoff response and sediment yield -governed by the redistribution of water and sediments in space and time. These are controlled by the topological architecture of the catchments that interacts with system states and the boundary conditions. Crossing the response thresholds means to establish connectedness of surface or subsurface flow paths to the catchment outlet. Subsurface stormflow in humid areas, overland flow and erosion in semi-arid and arid areas are examples, and explain that crossing local process thresholds is necessary but not sufficient to trigger a system response threshold. The third form of threshold behaviour involves changes in the "architecture" of human geoecosystems, which experience various disturbances. As a result substantial change in hydrological functioning of a system is induced, when the disturbances exceed the resilience of the geo-ecosystem. We present examples from savannah ecosystems, humid agricultural systems, mining activities affecting rainfall runoff in forested areas, badlands formation in Spain, and the restoration of the Upper Rhine river basin as examples of this phenomenon. This fun...

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Section: Biological Controls Of Hydrological Functioning In Pristine mentioning

confidence: 99%

Threshold behaviour in hydrological systems as (human) geo-ecosystems: manifestations, controls, implications

Zehe¹,

Sivapalan

2009

Hydrol. Earth Syst. Sci.

196

139

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“…Estudos envolvendo o efeito do preparo do solo sobre as características físicas e químicas, em profundidade no solo, normalmente produzem resultados variáveis, dependendo da textura, do sistema e tempo de preparo e da profundidade do solo avaliada. A ausência de preparo normalmente pode promover o aumento da densidade e o do teor de carbono orgânico nas camadas superficiais do solo; já o preparo do solo promove o aumento da macroporosidade e a redução da densidade do solo (Blewins et al, 1983;Dick, 1983;Shipitalo et al, 2000).…”

Section: Resultsunclassified

Persistência do acetochlor em solo sob semeadura direta e convencional

Ferri¹,

Vidal

2002

Planta daninha

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O manejo do solo pode alterar a persistência dos herbicidas e influi na atividade para controle de plantas daninhas, no potencial de injúria das culturas em sucessão e no risco de contaminação ambiental. Um experimento foi conduzido, no ano agrícola de 1999/2000, na Faculdade de Agronomia da Universidade Federal do Rio Grande do Sul, com o objetivo de avaliar a persistência do herbicida acetochlor em Argissolo Vermelho manejado sob semeadura direta e preparo convencional. A dose de acetochlor utilizada foi de 3.360 g ha-1. O delineamento experimental foi o de blocos casualizados, com três repetições. A persistência do herbicida acetochlor foi avaliada através de bioensaio, utilizando-se o trigo (Triticum aestivum) como planta indicadora. O herbicida acetochlor foi menos persistente no solo sob semeadura direta que sob preparo convencional, com meia-vida de 10 e 29 dias, respectivamente.

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“…A ausência de preparo normalmente proporciona aumento da densidade e do teor de carbono orgânico nas camadas superficiais do solo. Já o preparo do solo proporciona aumento da macroporosidade e redução da densidade do solo (Blewins et al, 1983;Dick, 1983;Shipitalo et al, 2000). O controle das plantas daninhas variou entre os sistemas de preparo do solo, as doses do herbicida acetochlor e as épocas de avaliações.…”

Section: Resultsunclassified

Controle de plantas daninhas na cultura da soja através do herbicida acetochlor em sistemas de semeadura direta e preparo convencional

Ferri¹,

Vidal

2002

Planta daninha

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Conservation tillage and macropore factors that affect water movement and the fate of chemicals

Cited by 235 publications

References 55 publications

Threshold behaviour in hydrological systems as (human) geo-ecosystems: manifestations, controls, implications

Threshold behaviour in hydrological systems as (human) geo-ecosystems: manifestations, controls, implications

Persistência do acetochlor em solo sob semeadura direta e convencional

Controle de plantas daninhas na cultura da soja através do herbicida acetochlor em sistemas de semeadura direta e preparo convencional

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