Temporal variability of structure and hydraulic properties of topsoil of three soil types

Abstract

The soil structure and hydraulic properties of arable soils considerably vary during the year due to the periodical tillage, fertilization, plant and root grow, climate impact etc. The knowledge of these soil properties is essential when assessing water regime and associated dissolved substance transport in soils. Temporal variability of soil properties measured in surface horizons of three soil types (Haplic Cambisol, Greyic Phaeozem, Haplic Luvisol) was studied in years from 2007 to 2010. Undisturbed soil samples were taken every month to evaluate the actual field soil-water content, bulk density, porosity and hydraulic properties. The grab soil samples were taken every month to evaluate aggregate stability using the WSA (water stable aggregates) index, pHH2O and pHKCl, soil organic matter content and quality. Unsaturated hydraulic conductivity for pressure head of −2cm was measured directly in the field using the minidisk tension infiltrometer. In addition soil structure was documented on micromorphological images.In some cases, the similar seasonal trends of the soil pHH2O, pHKCl, organic matter quality, bulk density, porosity or aggregate stability were observed in different soils. Parameters characterizing soil hydraulic properties were highly variable and did not show similar trends for different soils. This study showed different trends during different years. Thus data, which were obtained during one year period, could not be used to generalize soil properties development in particular soil and crop. The soil structure, aggregate stability and soil hydraulic properties were interrelated and depended on plant growth, rainfall and tillage. The drier conditions in some soils positively influenced the soil aggregate stability, slope of the retention curve at the inflection point and hydraulic conductivity. Probably due to the high variation of soil hydraulic properties no closer correlation between them and other properties was detected. The slope of the retention curve at the inflection point (e.g. indicator of soil physical quality) in many cases increased (decreased) when also the soil aggregate stability and hydraulic conductivity values increased (decreased). No closer correlation was revealed when analyzing these relationships for the entire observation period.