Influence of climatic conditions on soil physical properties under traditional and conservation tillage.

12 páginas.-- 2 figuras, 4 tablas.-- 16 referencias

This study was conducted to determine the effects of climatic conditions on soil physical properties under traditional and conservation tillage. The experiments were carried out in 1995 (dry year) and 1997 (wet year) in a sandy loam soil (Xerofluvent) in the province of Seville (southern Spain). The traditional tillage (TT) method consisted mainly of the use of mouldboard ploughing, and the conservation tillage (CT) was characterized by not using mouldboard ploughing, by reduction of the number of tillage operations and leaving the crop residues on the surface as mulch. In both tillage treatments a wheat (Triticum aestivum)-sunflower (Helianthus annuus) crop rotation was established. The crop of the experimental years was sunflower. In each treatment, systematic measurements of bulk density, resistance to penetration, and hydraulic conductivity (using tension disc infiltrometers) in the topsoil were carried out. Changes in water profiles through the experimental period were also followed using a neutron probe and time domain reflectometry. Soil bulk density, measured after tillage operations, was significantly higher in the conservation tillage treatment than in the traditional tillage treatment in the dry year. In the wet year, soil bulk density was not significantly different between treatments. Penetration resistance followed a similar trend to that of the bulk density. Hydraulic conductivity, in the dry year, was significantly higher in the TT than in the CT treatment at the pressure head of 0 mm. In contrast, in the wet year, was significantly higher in TT than in CT for all the pressure heads applied. The conservation tillage applied seems to be highly effective in enhancing soil water recharge and water conservation, particularly in the year with much lower than average precipitation.

This study was supported with funds of the Spanish CICYT, project the AG93-0613-CO2-01, and the Juanta de Andalucía (Research Group AGR 151)

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