HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.Improving the quantification of sediment source contributions using different mathematical models and spectral preprocessing techniques for individual or combined spectra of ultraviolet-visible, near-and middle-infrared spectroscopy
Combining spectroscopy and magnetism with geochemical tracers to improve the discrimination of sediment sources in a homogeneous subtropical catchment Rafael Ramon (a,b) ; Olivier Evrard (b) ; J. Patrick Laceby (c) ; Laurent Caner (d) , Alberto V.Inda (e) , Cláudia A.P. de Barros (e) ; Jean P.G. Minella (f) and Tales Tiecher (e)
Sediments produced from eroding cultivated land can cause on-site and off-site effects that cause considerable economic and social impacts. Despite the importance of soil conservation practices (SCP) for the control of soil erosion and improvements in soil hydrological functions, limited information is available regarding the effects of SCP on sediment yield (SY) at the catchment scale. This study aimed to investigate the long-term relationships between SY and land use, soil management, and rainfall in a small catchment. To determine the effects of anthropogenic and climatic factors on SY, rainfall, streamflow, and suspended sediment concentration were monitored at 10-min intervals for 14 years (2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016), and the land use and soil management changes were surveyed annually. Using a statistical procedure to separate the SY effects of climate, land use, and soil management, we observed pronounced temporal effects of land use and soil management changes on SY. During the first 2 years (2002)(2003)(2004), the land was predominantly cultivated with tobacco under a traditional tillage system (no cover crops and ploughed soil) using animal traction. In that period, the SY reached approximately 400 t·km −2 ·year −1 . From 2005 to 2009, a soil conservation programme introduced conservation tillage and winter cover crops in the catchment area, which lowered the SY to 50 t·km −2 ·year −1 . In the final period (2010)(2011)(2012)(2013)(2014)(2015)(2016), the SCP were partially abandoned by farmers, and reforested areas increased, resulting in an SY of 150 t·km −2 ·year −1 . This study also discusses the factors associated with the failure to continue using SCP, including structural support and farmer attitudes.
A compactação na soleira de implementos de mobilização de solo é passível de ocorrência em determinadas condições do solo. O objetivo deste estudo foi avaliar se há compactação abaixo da profundidade de trabalho de um subsolador e verificar o efeito deste implemento em solo com níveis diferenciados de compactação. Os tratamentos em estudo foram semeadura direta há 13 anos e semeadura direta com compactação adicional. Coletaram-se dados de esforço horizontal (F H), esforço de tração, (F T) esforço vertical (F V) e o momento associado (M O) à haste subsoladora, resistência específica operacional, área mobilizada, área de elevação, empolamento e resistência mecânica do solo à penetração, bem como parâmetros de descrição física do solo. A compactação adicional gerou um aumento de 18,9% no F H e no F T. A maior influência da compactação adicional foi no F V, onde gerou um incremento de 78,2% demonstrando que a ação da pressão da máquina é mais expressiva na direção vertical. A semeadura direta ofereceu a menor demanda de tração por área de solo mobilizada que o solo que sofreu compactação adicional. Ao invés de ocorrer compactação abaixo da camada escarificada, houve mobilização do solo pela ponteira do subsolador resultando em menor resistência mecânica à penetração dessa camada de solo.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.