<?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>S0187-57792011000300325</article-id>
<title-group>
<article-title xml:lang="es"><![CDATA[Concentración de nitrógeno en suelo por efecto de manejo orgánico y convencional]]></article-title>
<article-title xml:lang="en"><![CDATA[Nitrogen Concentration in Soil as Affected by Organic and Conventional Management]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Cristóbal-Acevedo]]></surname>
<given-names><![CDATA[D.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Álvarez-Sánchez]]></surname>
<given-names><![CDATA[M. E.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Hernández-Acosta]]></surname>
<given-names><![CDATA[E.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Améndola-Massiotti]]></surname>
<given-names><![CDATA[R.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,Universidad Autónoma Chapingo Departamento de Suelos ]]></institution>
<addr-line><![CDATA[ estado de México]]></addr-line>
<country>Mexico</country>
</aff>
<aff id="Af2">
<institution><![CDATA[,Universidad Autónoma Chapingo Departamento de Zootecnia ]]></institution>
<addr-line><![CDATA[ estado de México]]></addr-line>
<country>Mexico</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>09</month>
<year>2011</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>09</month>
<year>2011</year>
</pub-date>
<volume>29</volume>
<numero>3</numero>
<fpage>325</fpage>
<lpage>332</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S0187-57792011000300325&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S0187-57792011000300325&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S0187-57792011000300325&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="es"><p><![CDATA[Resumen En la actualidad se proponen sistemas de producción agrícola orgánicos como una opción sustentable en comparación con los sistemas convencionales. Sin embargo, al recomendar estos sistemas es necesario que sus ventajas sean demostradas de manera experimental con estudios de varios años. Con el objetivo de evaluar el efecto de los tratamientos de producción agrícola orgánica y convencional, sobre las concentraciones de nitrógeno (N) a 0, 30, 60, 90 y 120 cm de profundidad del suelo, se realizó un experimento en parcelas cultivadas con maíz. El experimento se llevó a cabo durante ocho ciclos de cultivo. Al final de los ciclos de cultivo de los años 2001 y 2008 se colectaron las muestras de suelo a las profundidades mencionadas y se les determinó la concentración de nitrato, amonio, N mineral, N total y N orgánico. Los datos fueron analizados como un diseño de tratamientos completamente al azar. Las ventajas del sistema orgánico después de ocho ciclos de cultivo de maíz fueron, un mejoramiento de las condiciones del suelo en la capa superficial (0 - 30 cm), al aumentar la concentración de materia orgánica de 1.66 a 1.83%, una mayor concentración de N orgánico y de N total debido a que las reservas de N total se incrementaron 40%, de las cuales más del 95% correspondieron a las reservas de N orgánico. La ventaja del sistema convencional después del mismo periodo en el cultivo de maíz, fue una mayor disponibilidad de nitrato, amonio y N mineral en la capa superficial (0-30 cm).]]></p></abstract>
<abstract abstract-type="short" xml:lang="en"><p><![CDATA[Abstract Currently it has been proposed that organic farming systems constitute a more sustainable option than those managed conventionally. However, to recommend these systems, it is necessary the evaluation of their potential benefits in long-term studies. In order to evaluate the effect of organic and conventional farming, on N concentrations at 0, 30, 60, 90, and 120 cm deep in soil, an experiment was conducted in plots planted with corn. The experiment was conducted during eight growing seasons. At the end of the growing seasons of 2001 and 2008 soil samples were collected at the depths above mentioned and the concentration of nitrate, ammonium, mineral N, total N and organic N were determined. The data were analyzed with a completely randomized design treatments. The advantages of the organic system after eight cycles of maize were an improvement in soil conditions in the surface layer (0 - 30 cm), increasing the organic matter concentration of 1.66 to 1.83%, a higher concentration of organic N and total N because total N reserves increased 40%, of which over 95% were organic N. The advantage of the conventional system after the same period in the cultivation of maize was an increased availability of nitrate, ammonium, and mineral N in the superficial layer (0-30 cm).]]></p></abstract>
<kwd-group>
<kwd lng="es"><![CDATA[nitratos]]></kwd>
<kwd lng="es"><![CDATA[amonio]]></kwd>
<kwd lng="es"><![CDATA[nitrógeno total]]></kwd>
<kwd lng="es"><![CDATA[nitrógeno orgánico]]></kwd>
<kwd lng="es"><![CDATA[residuos de cosecha]]></kwd>
<kwd lng="en"><![CDATA[nitrates]]></kwd>
<kwd lng="en"><![CDATA[ammonium]]></kwd>
<kwd lng="en"><![CDATA[total nitrogen]]></kwd>
<kwd lng="en"><![CDATA[organic nitrogen]]></kwd>
<kwd lng="en"><![CDATA[crop residues]]></kwd>
</kwd-group>
</article-meta>
</front><back>
<ref-list>
<ref id="B1">
<nlm-citation citation-type="">
<collab>ADAS</collab>
<source><![CDATA[Diffuse nitrate pollution from agriculture - strategies for reducing nitrate leaching. ADAS Report to Defra - supporting paper D3 for the consultation on implementation of the Nitrates Directive in England]]></source>
<year>2007</year>
<publisher-loc><![CDATA[UK ]]></publisher-loc>
</nlm-citation>
</ref>
<ref id="B2">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Estimación del aporte de nitrógeno del suelo para la fertilización racional de cultivos]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Benintende]]></surname>
<given-names><![CDATA[M. C.]]></given-names>
</name>
<name>
<surname><![CDATA[De Battista]]></surname>
<given-names><![CDATA[J. J.]]></given-names>
</name>
<name>
<surname><![CDATA[Benintende]]></surname>
<given-names><![CDATA[S. M.]]></given-names>
</name>
<name>
<surname><![CDATA[Saluzzio]]></surname>
<given-names><![CDATA[M. F.]]></given-names>
</name>
<name>
<surname><![CDATA[Muller]]></surname>
<given-names><![CDATA[C.]]></given-names>
</name>
<name>
<surname><![CDATA[Sterren]]></surname>
<given-names><![CDATA[M. A.]]></given-names>
</name>
</person-group>
<source><![CDATA[Ciencia, Docencia y Tecnología]]></source>
<year>2008</year>
<volume>19</volume>
<page-range>141-74</page-range></nlm-citation>
</ref>
<ref id="B3">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Is the productivity of organic farms restricted by the supply of available nitrogen?]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Berry]]></surname>
<given-names><![CDATA[P. M.]]></given-names>
</name>
<name>
<surname><![CDATA[Sylvester-Bradley]]></surname>
<given-names><![CDATA[R.]]></given-names>
</name>
<name>
<surname><![CDATA[Philipps]]></surname>
<given-names><![CDATA[L.]]></given-names>
</name>
<name>
<surname><![CDATA[Hatch]]></surname>
<given-names><![CDATA[D. J.]]></given-names>
</name>
<name>
<surname><![CDATA[Cuttle]]></surname>
<given-names><![CDATA[S. P.]]></given-names>
</name>
<name>
<surname><![CDATA[Rayns]]></surname>
<given-names><![CDATA[F. W.]]></given-names>
</name>
<name>
<surname><![CDATA[Gosling]]></surname>
<given-names><![CDATA[P.]]></given-names>
</name>
</person-group>
<source><![CDATA[Soil Use Manage]]></source>
<year>2002</year>
<volume>18</volume>
<page-range>248-55</page-range></nlm-citation>
</ref>
<ref id="B4">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Brenmer]]></surname>
<given-names><![CDATA[J. M.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Inorganic forms]]></article-title>
<person-group person-group-type="editor">
<name>
<surname><![CDATA[Black]]></surname>
<given-names><![CDATA[C. A.]]></given-names>
</name>
</person-group>
<source><![CDATA[Methods of soil analysis]]></source>
<year>1965</year>
<page-range>1179-237</page-range><publisher-loc><![CDATA[Madison, WI, USA ]]></publisher-loc>
<publisher-name><![CDATA[American Society of Agronomy, Agronomy 9]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B5">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Long-term trends in fertility of soils under continuous cultivation and cereal cropping in southern queensland. IX. Simulation of soil carbon and nitrogen pools using century model]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Chilcott]]></surname>
<given-names><![CDATA[C. R.]]></given-names>
</name>
<name>
<surname><![CDATA[Dalal]]></surname>
<given-names><![CDATA[R. C.]]></given-names>
</name>
<name>
<surname><![CDATA[Parton]]></surname>
<given-names><![CDATA[W. J.]]></given-names>
</name>
<name>
<surname><![CDATA[Carter]]></surname>
<given-names><![CDATA[J. O.]]></given-names>
</name>
<name>
<surname><![CDATA[King]]></surname>
<given-names><![CDATA[A. J.]]></given-names>
</name>
</person-group>
<source><![CDATA[Aust. J. Soil Res]]></source>
<year>2007</year>
<volume>45</volume>
<page-range>206-17</page-range></nlm-citation>
</ref>
<ref id="B6">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[The influence of season, agricultural management, and soil properties on gross nitrogen transformations and bacterial community structure]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Cookson]]></surname>
<given-names><![CDATA[W. R.]]></given-names>
</name>
<name>
<surname><![CDATA[Marschner]]></surname>
<given-names><![CDATA[P.]]></given-names>
</name>
<name>
<surname><![CDATA[Clark]]></surname>
<given-names><![CDATA[I. M.]]></given-names>
</name>
<name>
<surname><![CDATA[Milton]]></surname>
<given-names><![CDATA[N.]]></given-names>
</name>
<name>
<surname><![CDATA[Smirk]]></surname>
<given-names><![CDATA[M. N.]]></given-names>
</name>
<name>
<surname><![CDATA[Murphy]]></surname>
<given-names><![CDATA[D. V.]]></given-names>
</name>
<name>
<surname><![CDATA[Osman]]></surname>
<given-names><![CDATA[M.]]></given-names>
</name>
<name>
<surname><![CDATA[Stockdale]]></surname>
<given-names><![CDATA[E. A.]]></given-names>
</name>
<name>
<surname><![CDATA[Hirsch]]></surname>
<given-names><![CDATA[P. R.]]></given-names>
</name>
</person-group>
<source><![CDATA[Aust. J. Soil Res]]></source>
<year>2006</year>
<volume>44</volume>
<page-range>453-65</page-range></nlm-citation>
</ref>
<ref id="B7">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Soil quality and barley growth as influenced by the land application of two compost types]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Courtney]]></surname>
<given-names><![CDATA[R. G.]]></given-names>
</name>
<name>
<surname><![CDATA[Mullen]]></surname>
<given-names><![CDATA[G. J.]]></given-names>
</name>
</person-group>
<source><![CDATA[Bioresour. Technol.]]></source>
<year>2008</year>
<volume>99</volume>
<page-range>2913-8</page-range></nlm-citation>
</ref>
<ref id="B8">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Long-term trends in total nitrogen of a vertisol subjected to zero-tillage, nitrogen application and stubble retention]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Dalal]]></surname>
<given-names><![CDATA[R. C.]]></given-names>
</name>
</person-group>
<source><![CDATA[Aust. J. Soil Res.]]></source>
<year>1992</year>
<volume>30</volume>
<page-range>223-31</page-range></nlm-citation>
</ref>
<ref id="B9">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Soil properties under organic and conventional management in southern New South Wales]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Derrick]]></surname>
<given-names><![CDATA[J. W.]]></given-names>
</name>
<name>
<surname><![CDATA[Dumaresq]]></surname>
<given-names><![CDATA[D. C.]]></given-names>
</name>
</person-group>
<source><![CDATA[Aust. J. Soil Res.]]></source>
<year>1999</year>
<volume>37</volume>
<page-range>1047-55</page-range></nlm-citation>
</ref>
<ref id="B10">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Influence of alternative and conventional agricultural management on soil microbial processes and nitrogen availability]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Doran]]></surname>
<given-names><![CDATA[J. W.]]></given-names>
</name>
<name>
<surname><![CDATA[Fraser]]></surname>
<given-names><![CDATA[D. G.]]></given-names>
</name>
<name>
<surname><![CDATA[Culik]]></surname>
<given-names><![CDATA[M. N.]]></given-names>
</name>
<name>
<surname><![CDATA[Liebhardt]]></surname>
<given-names><![CDATA[W. C.]]></given-names>
</name>
</person-group>
<source><![CDATA[Am. J. Alt. Agric.]]></source>
<year>1987</year>
<volume>2</volume>
<page-range>99-106</page-range></nlm-citation>
</ref>
<ref id="B11">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Simulation of nitrogen balance of maize field under different drainage strategies using the drainmod-n model]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[El-Sadek]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
<name>
<surname><![CDATA[Feyen]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
<name>
<surname><![CDATA[Ragab]]></surname>
<given-names><![CDATA[R.]]></given-names>
</name>
</person-group>
<source><![CDATA[Irrig. Drain.]]></source>
<year>2002</year>
<volume>51</volume>
<page-range>61-75</page-range></nlm-citation>
</ref>
<ref id="B12">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Etchevers B.]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
</person-group>
<source><![CDATA[Análisis químico de suelos y plantas]]></source>
<year>1988</year>
<publisher-loc><![CDATA[Montecillo, estado de México ]]></publisher-loc>
<publisher-name><![CDATA[Centro de Edafología, Colegio de Posgraduados]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B13">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Green manuring in crop production]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Fageria]]></surname>
<given-names><![CDATA[N. K.]]></given-names>
</name>
</person-group>
<source><![CDATA[J. Plant Nut.]]></source>
<year>2007</year>
<volume>30</volume>
<page-range>691-719</page-range></nlm-citation>
</ref>
<ref id="B14">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Limitations of neoclassical economics for evaluating sustainability of agricultural systems: Comparing organic and conventional systems]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Flores]]></surname>
<given-names><![CDATA[C. C.]]></given-names>
</name>
<name>
<surname><![CDATA[Sarandón]]></surname>
<given-names><![CDATA[S. J.]]></given-names>
</name>
</person-group>
<source><![CDATA[J. Sust.]]></source>
<year>2004</year>
<volume>24</volume>
<page-range>77-91</page-range></nlm-citation>
</ref>
<ref id="B15">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[García]]></surname>
<given-names><![CDATA[E.]]></given-names>
</name>
</person-group>
<source><![CDATA[Modificaciones al sistema de clasificación climática de Köppen]]></source>
<year>1988</year>
<publisher-loc><![CDATA[México, D. F. ]]></publisher-loc>
<publisher-name><![CDATA[Instituto de Geografía, Universidad Nacional Autónoma de México]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B16">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Havlin]]></surname>
<given-names><![CDATA[J. L.]]></given-names>
</name>
<name>
<surname><![CDATA[Tisdale]]></surname>
<given-names><![CDATA[S. L.]]></given-names>
</name>
<name>
<surname><![CDATA[Nelson]]></surname>
<given-names><![CDATA[W. L.]]></given-names>
</name>
<name>
<surname><![CDATA[Beaton]]></surname>
<given-names><![CDATA[J. D.]]></given-names>
</name>
</person-group>
<source><![CDATA[Soil fertility and fertilizers: An introduction to nutrient Management]]></source>
<year>1993</year>
<publisher-loc><![CDATA[New York, NY, USA ]]></publisher-loc>
<publisher-name><![CDATA[Macmillan Publishing]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B17">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Comparison between organic and mineral fertilization for soil fertility levels: Crop macronutrient concentrations and yield]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Herencia]]></surname>
<given-names><![CDATA[J. F.]]></given-names>
</name>
<name>
<surname><![CDATA[Ruiz-Porras]]></surname>
<given-names><![CDATA[J. C.]]></given-names>
</name>
<name>
<surname><![CDATA[Melero]]></surname>
<given-names><![CDATA[S.]]></given-names>
</name>
<name>
<surname><![CDATA[Garcia-Galavis]]></surname>
<given-names><![CDATA[P. A.]]></given-names>
</name>
<name>
<surname><![CDATA[Morillo]]></surname>
<given-names><![CDATA[E.]]></given-names>
</name>
<name>
<surname><![CDATA[Maqueda]]></surname>
<given-names><![CDATA[C.]]></given-names>
</name>
</person-group>
<source><![CDATA[Agron. J.]]></source>
<year>2007</year>
<volume>99</volume>
<page-range>973-83</page-range></nlm-citation>
</ref>
<ref id="B18">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Modeling urea, ammonium, and nitrate transport and transformations in flooded soil columns]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Liwang]]></surname>
<given-names><![CDATA[Ma]]></given-names>
</name>
<name>
<surname><![CDATA[Lindau]]></surname>
<given-names><![CDATA[C. W.]]></given-names>
</name>
<name>
<surname><![CDATA[Hongprayoon]]></surname>
<given-names><![CDATA[C.]]></given-names>
</name>
<name>
<surname><![CDATA[Burhan]]></surname>
<given-names><![CDATA[W.]]></given-names>
</name>
<name>
<surname><![CDATA[Jang]]></surname>
<given-names><![CDATA[B. C.]]></given-names>
</name>
<name>
<surname><![CDATA[Patrick Jr.]]></surname>
<given-names><![CDATA[W. H.]]></given-names>
</name>
<name>
<surname><![CDATA[Selim]]></surname>
<given-names><![CDATA[H. M.]]></given-names>
</name>
</person-group>
<source><![CDATA[Soil Sci.]]></source>
<year>1999</year>
<volume>164</volume>
<page-range>123-32</page-range></nlm-citation>
</ref>
<ref id="B19">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Evaluating the benefits of organic farming in rice agroecosystems in the Philippines]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Mendoza]]></surname>
<given-names><![CDATA[T. C.]]></given-names>
</name>
</person-group>
<source><![CDATA[J. Sust. Agric.]]></source>
<year>2004</year>
<volume>24</volume>
<page-range>93-115</page-range></nlm-citation>
</ref>
<ref id="B20">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Transition from intensive tillage to no-tillage and organic diversified annual cropping systems]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Miller]]></surname>
<given-names><![CDATA[P. R.]]></given-names>
</name>
<name>
<surname><![CDATA[Buschena]]></surname>
<given-names><![CDATA[D. E.]]></given-names>
</name>
<name>
<surname><![CDATA[Jones]]></surname>
<given-names><![CDATA[C. A.]]></given-names>
</name>
<name>
<surname><![CDATA[Holmes]]></surname>
<given-names><![CDATA[J. A.]]></given-names>
</name>
</person-group>
<source><![CDATA[Agron J.]]></source>
<year>2008</year>
<volume>100</volume>
<page-range>591-9</page-range></nlm-citation>
</ref>
<ref id="B21">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Effects of repeated straw incorporation on crop fertilizer nitrogen requirements, soil mineral nitrogen and nitrate leaching losses]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Nicholson]]></surname>
<given-names><![CDATA[F. A.]]></given-names>
</name>
<name>
<surname><![CDATA[Chambers]]></surname>
<given-names><![CDATA[B. J.]]></given-names>
</name>
<name>
<surname><![CDATA[Mills]]></surname>
<given-names><![CDATA[A. R.]]></given-names>
</name>
<name>
<surname><![CDATA[Strachan]]></surname>
<given-names><![CDATA[P. J.]]></given-names>
</name>
</person-group>
<source><![CDATA[Soil Use Manage]]></source>
<year>1997</year>
<volume>13</volume>
<page-range>136-42</page-range></nlm-citation>
</ref>
<ref id="B22">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Use of compost to improve soil properties and crop productivity under low input agricultural system in West Africa]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Ouédraogo]]></surname>
<given-names><![CDATA[E.]]></given-names>
</name>
<name>
<surname><![CDATA[Mando]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
<name>
<surname><![CDATA[Zombré]]></surname>
<given-names><![CDATA[N. P.]]></given-names>
</name>
</person-group>
<source><![CDATA[Agric. Ecosyst. Environ.]]></source>
<year>2001</year>
<volume>84</volume>
<page-range>259-66</page-range></nlm-citation>
</ref>
<ref id="B23">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Cycling of fertilizer and cotton crop residue]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Rochester]]></surname>
<given-names><![CDATA[I. J.]]></given-names>
</name>
<name>
<surname><![CDATA[Constable]]></surname>
<given-names><![CDATA[G. A.]]></given-names>
</name>
<name>
<surname><![CDATA[Macleod]]></surname>
<given-names><![CDATA[D. A.]]></given-names>
</name>
</person-group>
<source><![CDATA[Aust. J. Soil Res.]]></source>
<year>1993</year>
<volume>31</volume>
<page-range>597-609</page-range></nlm-citation>
</ref>
<ref id="B24">
<nlm-citation citation-type="book">
<collab>SAS</collab>
<source><![CDATA[SAS. User´s guide. Versión 8.1]]></source>
<year>2000</year>
<publisher-loc><![CDATA[Cary, NC, USA ]]></publisher-loc>
<publisher-name><![CDATA[SAS Institute]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B25">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[On the fate of anthropogenic nitrogen]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Schlesinger]]></surname>
<given-names><![CDATA[W. H.]]></given-names>
</name>
</person-group>
<source><![CDATA[Proc. Natl. Acad. Sci. USA.]]></source>
<year>2008</year>
<volume>106</volume>
<page-range>203-8</page-range></nlm-citation>
</ref>
<ref id="B26">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Nitrate leaching from organic farms and conventional farms following best practice]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Stopes]]></surname>
<given-names><![CDATA[C.]]></given-names>
</name>
<name>
<surname><![CDATA[Lord]]></surname>
<given-names><![CDATA[E. I.]]></given-names>
</name>
<name>
<surname><![CDATA[Philipps]]></surname>
<given-names><![CDATA[L.]]></given-names>
</name>
<name>
<surname><![CDATA[Woodward]]></surname>
<given-names><![CDATA[L.]]></given-names>
</name>
</person-group>
<source><![CDATA[Soil Use Manage]]></source>
<year>2002</year>
<volume>18</volume>
<page-range>256-63</page-range></nlm-citation>
</ref>
<ref id="B27">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Intensive measurement of nitrous oxide emissions from a corn-soybean-wheat rotation under two contrasting management systems over 5 years]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Wagner-Riddle]]></surname>
<given-names><![CDATA[C.]]></given-names>
</name>
<name>
<surname><![CDATA[Furon]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
<name>
<surname><![CDATA[McLaughlin]]></surname>
<given-names><![CDATA[N. L.]]></given-names>
</name>
<name>
<surname><![CDATA[Lee]]></surname>
<given-names><![CDATA[I.]]></given-names>
</name>
<name>
<surname><![CDATA[Barbeau]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
<name>
<surname><![CDATA[Jayasundara]]></surname>
<given-names><![CDATA[S.]]></given-names>
</name>
<name>
<surname><![CDATA[Parkin]]></surname>
<given-names><![CDATA[G.]]></given-names>
</name>
<name>
<surname><![CDATA[von Bertoldi]]></surname>
<given-names><![CDATA[P.]]></given-names>
</name>
<name>
<surname><![CDATA[Warland]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
</person-group>
<source><![CDATA[Global Change Biol.]]></source>
<year>2007</year>
<volume>13</volume>
<page-range>1722-36</page-range></nlm-citation>
</ref>
<ref id="B28">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[An examination of the degthareff method for determining soil organic and a proposed modification of chromic acid titration method]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Walkey]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
<name>
<surname><![CDATA[Black]]></surname>
<given-names><![CDATA[I. A.]]></given-names>
</name>
</person-group>
<source><![CDATA[Soil Sci.]]></source>
<year>1947</year>
<volume>37</volume>
<page-range>29-38</page-range></nlm-citation>
</ref>
</ref-list>
</back>
</article>
