Resumo

ALVAREZ, Carina R et al. Decompaction of no-tillage soils: effects on soil properties and crops. Cienc. suelo [online]. 2009, vol.27, n.2, pp.159-169. ISSN 1850-2067.

Mechanical decompaction may improve the physical properties of no-tillage silty loam soils. The aims of this study were to: 1- evaluate the influence of mechanical tilling (e.g. paratill or cultivie) on soil physical (gravimetric water content, bulk density, penetration resistance and infiltration rate) and chemical (nitrate content) properties in no-tillage soils; 2- quantify the impact of soil decompaction on maize yield; and 3- evaluate the persistence of soil compaction alleviation on soil penetration resistance, root abundance and crop yields after maize. Six field experiments were conducted in no-tillage maize plots in the Rolling Pampa region. Paired plots were compared: continuous no tillage (TEST) vs. soil compaction alleviation by deep tillage (DESC). Soil penetration resistance decreased by 37and 24 % (p < 0.05) at the 0-25 cm and 0-40 cm soil layers, respectively, and the soil infiltration rate increased (p= 0.07) from TEST to DESC at the V5-V6 maize growing stage. No deep tillage effect was observed on soil bulk density and nitrate content. Maize yields were significantly augmented by soil compaction alleviation (p < 0.001) with an average response of 659 kg ha-¹ (5.56%). All sites showed economic benefits. No residual effects were found in soil physical properties, root growth and yield in the following crops. The results indicate shortterm effects of soil decompaction by deep tillage on soil penetration resistance and maize yield, but no residual effects on subsequent crops.

Palavras-chave : Penetration resistance; Soil water infiltration; Physical properties; Maize; Roots.

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