Maximum soil density of Entisols as a function of silt content

<div><p>ABSTRACT: Degradation that occursin agricultural soils causes compaction.Soil density (DS) analysis has been reported to be an unreliable method of measuring the extent of soil compaction, because it varies with the soil granulometric composition and organic matter (OM)content. However, soil relative density (DR) is a good indicator that facilitates the measurement of the degree of compaction and thus, soil comparison and management techniques. Quotient between the DS and its maximum density (Dsmax) gives the DR. This study aimed to assess the effect of the granulometric composition on the physical-hydrological properties of the high-silt containing soils,under no tillage. Samples from disturbed and undisturbed structures of 18 soils were collected from the state of Rio Grandedo Sul following the no-tillage system. Once the granulometric size, OM content, soil density, maximum soil density and relative density were determined,the results indicated a drop in the Dsmax value when silt and MO were added;however, the addition of clay and clay-plus-silt revealed no significant effect. When the silt and MO content increased the soil density decreased. The DR, however, was not affected by either the granulometric composition or OM content. A difference was observed between the DR calculated from the determined Dsmax and that estimated by the Dsmax assessed based on the clay levels.Silt content was reported to exert a different influence on the physical-water properties of the silt soils than the clayey ones.</p></div

Programa Nacional de Alimentação Escolar (PNAE) e a participação da agricultura familiar em municípios do Rio Grande do Sul.

<span style="font-family: Times New Roman; font-size: small;"> </span><p class="MsoNormal" style="margin: 0cm 0cm 0pt; text-align: justify; line-height: 150%; text-indent: 35.4pt;"><span style="line-height: 150%; font-family: &quot;Times New Roman&quot;,&quot;serif&quot;; font-size: 12pt;">O Programa Nacional de Alimenta&ccedil;&atilde;o Escolar (PNAE) ampliado em 2009 tem por objetivo fornecer produtos da agricultura familiar para merenda escolar no &acirc;mbito estadual e municipal beneficiando 13 milh&otilde;es de escolares em todo o pa&iacute;s. O objetivo do trabalho foi conhecer e avaliar o desempenho do PNAE em munic&iacute;pios da Regi&atilde;o Noroeste do Rio Grande do Sul. Foram realizados levantamentos junto a Emater, Secret&aacute;ria de Desenvolvimento Rural e Secret&aacute;ria da Educa&ccedil;&atilde;o em quinze munic&iacute;pios da regi&atilde;o para obter os dados referentes ao n&uacute;mero de escolas atendidas, n&uacute;mero de produtores fornecedores de alimentos e os principais g&ecirc;neros aliment&iacute;cios fornecidos ao programa. Os resultados obtidos permitiram identificar o n&uacute;mero de produtores rurais participantes e as escolas que s&atilde;o beneficiadas pelo programa. O PNAE proporciona incentivo e desenvolvimento da pequena propriedade rural criando mecanismos para o fortalecimento dos agricultores familiares, a forma&ccedil;&atilde;o de h&aacute;bitos alimentares saud&aacute;veis e o desenvolvimento local nos munic&iacute;pios brasileiros.</span></p><span style="font-family: Times New Roman; font-size: small;"> </span><p class="MsoNormal" style="margin: 0cm 0cm 0pt; text-align: justify; line-height: 150%; text-indent: 35.4pt;"><span style="line-height: 150%; font-family: &quot;Times New Roman&quot;,&quot;serif&quot;; font-size: 12pt;"> </span></p><span style="font-family: Times New Roman; font-size: small;"> </span