Changes in soil organic matter, bulk density and tensile strength of aggregates after percolation in soils after conservation and conventional tillage
E. Urbanek 1
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Institute for Plant Nutrition and Soil Science, Christian-Albrechts University, Hermann-Rodewald 2, D-24118 Kiel, Germany
Int. Agrophys. 2006, 20(3): 245–254
The type of tillage in arable soils affects porosity of the soil and in consequence the hydraulic conductivity. The accessibility and mobility of organic carbon in arable soils can differ depending on the type of tillage. The highest differences between conventional or conservation tillage are found in the top-soil layer of the A horizon in pore size distribution and organic matter content. Total porosity and pore continuity influence the hydraulic conductivity and also the exchange processes in structured soil. Percolation of soil can provide not only information on hydraulic conductivity of structured soil but also about the accessibility of fixed organic matter. The aim of this study was to find out how the type of the soil tillage influences the hydraulic conductivity and accessibility of organic carbon in the topsoil. Soil samples from the topsoil layer under conventional and conservation tillage were percolated with distilled water and pyrophosphate solution. The differences in hydraulic conductivity between samples resulted in various amount of the organic carbon leached out. Organic carbon content (Corg), bulk density (dB) and tensile strength (Ts) of soil aggregates after percolation have changed in comparison with the non-percolated soil and show in which aggregate fraction the organic carbon was easily available for leaching out. The highest Corg reduction was found in smaller aggregates in comparison with larger aggregates, which resulted in the tensile strength of macroaggregates being very little affected by percolation.