Resumo

ARUANI, Martía Cristina; SANCHEZ, Enrique  e  REEB, Pablo. Changes in soil properties in a loamy soil under organic production of apples using cover crops. Cienc. suelo [online]. 2006, vol.24, n.2, pp.131-137. ISSN 1850-2067.

Orchard floor management in the Rio Negro valley is based on continuous tillage which in the long term may negatively affect soil properties. Therefore, the aim of this research was to evaluate the effect of different soil management treatments in an organic apple orchard (Malus domestica Bork.) cv. Royal Gala on nutrient availability, soil aggregates stability and organic carbon (CO) and total nitrogen (Nt) concentration in soil aggregates in a loamy soil. In March 1999, cover treatments applied to the inter-row spaces were: 1) permanent cover of fescue (Festuca arundinacea) plus alfalfa (Medicago sativa) (A+F); 2) permanent cover of strawberry clover (Trifolium fragiferum) (Tr); 3) seeding of common vetch (Vicia sativa) (V); and 4) control, natural soil vegetation and disking twice in late winter (T). In November 2002, soil samples were taken at three soil depths, 0-7.5; 7.5-15, and 15-30 cm to determine soil organic matter (OM), total nitrogen (Nt), available phosphorus (P) and exchangeable bases (Ca⁺², K⁺ and Mg⁺²). In the top 0-7.5 cm macro aggregate (100-2,000 µm) micro aggregate (0-100 µm) fractions and the content of OM, OC and Nt were determined. Organic matter and Nt concentration in the perennial cover crops treatments (A+F and Tr) increased, and K⁺ were higher only in the 0-7.5 cm soil depths respect the V and T treatments. Magnesium concentration increased two-fold in the top 15 cm of soil in A+F compared to T. Calcium concentrations in A+F and Tr were higher than T at all soil depths and for the top 15 cm, respectively. In the T treatment macro-aggregates diminished and microaggregates increased due to soil cultivation compared to the perennial cover crops.

Palavras-chave : Distribution of aggregates; Nutrient availability; Entisols.

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