<?xml version="1.0" encoding="ISO-8859-1"?><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<front>
<journal-meta>
<journal-id>0187-5779</journal-id>
<journal-title><![CDATA[Terra Latinoamericana]]></journal-title>
<abbrev-journal-title><![CDATA[Terra Latinoam]]></abbrev-journal-title>
<issn>0187-5779</issn>
<publisher>
<publisher-name><![CDATA[Sociedad Mexicana de la Ciencia del Suelo A.C.]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S0187-57792014000300195</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[Soil organic carbon fractions as influenced by soybean cropping in the humid Pampa of Argentina]]></article-title>
<article-title xml:lang="es"><![CDATA[Influencia del cultivo de soja en las fracciones de carbono orgánico del suelo en la Pampa húmeda Argentina]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Conti]]></surname>
<given-names><![CDATA[Marta E.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[González]]></surname>
<given-names><![CDATA[Mirta G.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Gómez]]></surname>
<given-names><![CDATA[Elena]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Ferrero Holtz]]></surname>
<given-names><![CDATA[Esteban]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Moreno]]></surname>
<given-names><![CDATA[Gisela]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,Universidad de Buenos Aires Facultad de Agronomía Departamento de Suelos]]></institution>
<addr-line><![CDATA[Buenos Aires ]]></addr-line>
<country>Argentina</country>
</aff>
<aff id="Af2">
<institution><![CDATA[,Universidad Nacional de Rosario Facultad de Ciencias Agrarias ]]></institution>
<addr-line><![CDATA[Zavalla ]]></addr-line>
<country>Argentina</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>09</month>
<year>2014</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>09</month>
<year>2014</year>
</pub-date>
<volume>32</volume>
<numero>3</numero>
<fpage>195</fpage>
<lpage>200</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S0187-57792014000300195&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S0187-57792014000300195&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S0187-57792014000300195&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[The sustainability of continuous cropping systems depends heavily on the years of intensive agricultural production and the choice of crop sequence that alters the fractions of soil organic matter. The aim of this study was to evaluate the impact of continuous soybean cultivation on fractions of organic carbon in the vertic Argiudolls of the Argentinean Pampas. Total organic carbon (TOC), particulate organic carbon (POC ), fulvic acids (FA), humic acids (HA), humin (H) and carbon produced by microbial respiration (Cresp) were assessed in plots with continuous production of soybean for over 15 years (SP) and grassland plots that were considered the change control (GP). A significant reduction of TOC and POC variables in cultured soybean SP plots, relative to grassland GP, was observed. The POC / TOC and Cresp / TOC ratios were significantly lower in soybean plots than in grasslands used as controls. These ratios were interpreted as a preferential tendency to maintain high rates of mineralization of labile carbon forms and increased biological stability of humified forms in cultured soybean plots. The shapes of the humic fractions of less complexity, FA and HA, were significantly reduced in the latter plots compared with grasslands, while no significant changes occurred in the more stable and recalcitrant forms of carbon, such as humin, in either plot type.]]></p></abstract>
<abstract abstract-type="short" xml:lang="es"><p><![CDATA[La sostenibilidad de los sistemas agrícolas continuos depende en gran medida de los años de producción agrícola intensiva y de la elección de la secuencia de cultivos que alteran las fracciones de la materia orgánica edáfica. El objetivo de este trabajo fue evaluar el impacto del cultivo continuo de soja en las fracciones de carbono orgánico en Argiudoles Verticos de la Pampa Húmeda Argentina. El carbono orgánico total (COT), carbono orgánico particulado (POC), ácidos fúlvicos (AF), ácidos húmicos (AH), huminas (H) y carbono producido por la respiración microbiana (Cresp) fueron evaluados en parcelas con producción de soja continua de más de 15 años (SP), y en parcelas de pastizales que se consideraron como control (GP) del cambio. Se observó una reducción significativa en los contenidos de TOC y POC en las parcelas cultivadas con soja SP en relación a las de pastizales GP. Las relaciones POC / TOC y Cresp / TOC fueron significativamente más bajas en las parcelas con soja que en los pastizales empleados como control, que fueron interpretadas como una tendencia preferencial de mantener altas tasas de mineralización de las formas lábiles de carbono y mayor estabilidad biológica de las formas humificadas en parcelas cultivadas con soja. Las formas de las fracciones húmicas de menor complejidad, FA y HA, se redujeron significativamente en estas últimas parcelas en comparación con los pastizales, mientras que no hubo cambios significativos en las formas más estables y recalcitrantes de carbono, como las huminas, en ambos tipo de parcelas.]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[cropping systems]]></kwd>
<kwd lng="en"><![CDATA[soil organic matter]]></kwd>
<kwd lng="en"><![CDATA[soil organic carbon fractions]]></kwd>
<kwd lng="es"><![CDATA[sistemas de cultivo]]></kwd>
<kwd lng="es"><![CDATA[materia orgánica edáfica]]></kwd>
<kwd lng="es"><![CDATA[fracciones húmicas]]></kwd>
</kwd-group>
</article-meta>
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