Suitability of Various Parameters for the Determination of the Condition of Soil Structure with Dependence to the Quantity and Quality of Soil Organic Matter

Soil structure (SS) plays an important role in relation to climatic change, with the most important task the decreasing of CO 2 in the atmosphere by carbon sequestration in the soil and the prevention of floods by better water infiltration into the soil. However, the evaluation of its condition is very different because of the various parameters and their inappropriate uses. The aim of this study was to determine the responses of the parameters of SS on the soil type and tillage system as the most important factors that influence it through changes in the soil organic matter and soil texture. The soil factor, which was represented by seven soil types (EF, Eutric Fluvisol; MF, Mollic Fluvisol; HC, Haplic Chernozem; HL, Haplic Luvisol; ER, Eutric Regosol; EG, Eutric Gleysol; DS, Distric Stagnosol), should be included in all evaluations of SS because of the specifics of each soil type. The tillage factor (shallow non-inversion-reduced, RT; deeper with inversion-conventional, CT) was chosen because of a high sensitivity of SS to soil disruption by cultivation, which represents high potential for the mitigation of climate change. The study included 126 sampling places in different parts of Slovakia on real farms (7 soil types × 3 localities × 3 crop rotations × 2 tillage systems × 2 soil depths). The soils were analysed for the aggregate fraction composition, particle size distribution, and parameters of organic carbon. The data of different parameters of SS were calculated and evaluated. The most sensitive parameter of the tested ones was the coefficient of structure (K st ), which manifested up to the level of the fractions of humus substances and indicated a better condition of SS in more productive soils than less productive soils. The coefficient of soil structure vulnerability (K v ) and mean weight diameter in water-resistant macroaggregates (MWD w ) showed a worse condition of SS in the soils, which developed on Neogene sediments. A better condition of SS in RT was predicted particularly by the primary parameters (index of crusting, I c ; critical content of soil organic matter, S t ), and in CT, they were mainly the secondary parameters (K st ; water-resistant of soil aggregates, K w ). Overall, the suitability of the parameters of SS should be evaluated in relation to a specific soil type with its characteristics and should not be used universally.