ИСТИНА

Soil structure controls a number of functions such as water flow and its retention, transport of nutrients and related processes. While we all understand that the structure is dynamic for most structured soils and is affected by wetting-drying, freezing-thawing, and swelling-shrinkage cycles, such processes are usually ”left out” of consideration in majority of soil physical models. In this contribution we try to address at least one of these pillars by asking two questions: to what extent wetting-drying cycles affect soil structure and how does it influence soil hydraulic functions. To make such analysis meaningful, we further limit our study to steady state wetting-drying cycles. We characterise structure dynamics within conventional soil cores in wetting-drying cycle using a combination of water retention curve (WRC) and µCT measurements. Soil cores from A, E, and Bt horizons from Eutric Albic Retisol (Moscow region, Russia) were used in 3 replicates for such parallel experiments. At first, soil cores were scanned using X-ray µCT under field conditions. Then cores were slowly saturated and dried with the help of sand and sand-kaolin box method at a wide range of pFs: 0.4-0-0.4- 1-1.5-1.8-2.0-2.3-2.7 and by oven-drying (3 days + 3 days under T=50oC; 7 days under T=105oC), underlined conditions were scanned using µCT. Pore and solid structural changes in the form of morphological characteristics were computed and analized through the whole wetting-drying cycle and will be presented at our poster. The reported study was funded by RFBR according to the research project No 18-34-20131.