Freezing-thawing impact on aggregate stability as affected by land management, soil genesis and soil chemical and physical quality

Soil structure formation and soil aggregate stability are affected by anthropogenic and natural environmental factors and are of great interest worldwide. The goal of this paper was to determine the effect of soil freezing-thawing processes on the formation of water-stable aggregates (WSA) in two soil types – Cambisol (Central Lithuania) and Retisol (Western Lithuania) in relation to soil organic carbon content (SOC), type of land use and soil tillage intensity. Three successive freezing-thawing cycles were implemented in a laboratory at three soil water contents (air-dry – WSAAD, field capacity – WSAFC and near full saturation – WSANS) on soil cores taken from the 0 to 10, 10 to 25 and 25 to 40 cm layers of long-term conventional tillage (CT) and reduced tillage (RT) field trials of arable land as well as from the forest soil. Soil bulk density (BD), Nₜₒₜₐₗ, C/N ratio, Pₜₒₜₐₗ, and Kₜₒₜₐₗ were determined.WSA content in the Cambisol was significantly lower than in the Retisol at all soil water contents. WSA, averaged across soil types, land uses and soil depths, tended to decrease in the following order: air-dry soil > soil with water content at field capacity > soil near full saturation. In the Cambisol, CT management led to a 3.4-fold lower WSA under air-dry soil conditions, compared to the forest soil. In the Retisol, at all soil water contents, CT decreased WSA content 2.2-, 2.1- and 2.7-fold, respectively, compared to WSA in the forest soil. RT management in the Retisol increased the amount of WSA compared to CT through higher SOC content and lower soil BD. In the Cambisol and the Retisol, the SOC content acted as a direct factor for WSAFC. High soil BD acted as an indirect negative factor for aggregate stability at all three soil water contents. The potential of WSA in the Retisol for functioning and sustaining better WSAFC within the whole 0−40 cm soil layer is higher than the potential of WSA in the Cambisol. This study demonstrates that long-term RT management ensured higher WSAFC content than CT. Water-stable aggregate in the Retisol for functioning and sustaining better WSAAD is higher than in the Cambisol. If dry meteorological conditions prevailed in moderate climate zone, RT management would have a promising future for soil sustainability by maintaining higher WSA.