SOIL STRUCTURE CHANGES IN SUBSOILED SOLONETZIC AND CHERNOZEMIC SOILS MEASURED BY IMAGE-ANALYSIS

Deep tillage of soils with dense or compacted layers increases soil water penetration and root proliferation, which indicates increased soil porosity, especially of vertical macropores. Difference image analysis using photographs of air-dried soil profiles makes it possible to identify and characterize soil macropores of large soil samples in situ without soil disturbance. The objective of this study was to determine the effect of deep-tillage systems on the characteristics and distribution of different types of soil macropores over a two-year period and to relate these to soil-water movement. Soil loosening with deep ripping was more pronounced and longer lasting than that with paraplowing and involved the planar, intermediate and rounded soil macropores, whereas soil loosening with paraplowing was minimal and involved mainly the planar and intermediate soil macropores. Deep ripping increased the number of vertical macropores; paraplowing had little effect on pore orientation. The increased soil macroporosity had resulted in increased soil-water recharge and increased crop water-use-efficiency. Image analysis was an essential tool for studying the type of soil disturbance created by two different subsoilers on different kinds of soil.