Enev V., Pospíšilová L., Klučáková M., Liptaj T., Doskočil L. (2014): Spectral characterization of selected humic substances. Soil & Water Res., 9: 9-17.Current concern for soil quality has stimulated research on soil organic matter (OM). Humic substances (HS) of different origin were compared applying ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), "steady-state" fluorescence spectroscopy, and 13 C nuclear magnetic resonance ( 13 C NMR).Sodium humates samples were isolated from soil (Gleyic Luvisol), compost, and South-Moravian lignite from the mine Mír in Mikulčice. Sodium humates (SH) were extracted by a conventional procedure recommended by the International Humic Substances Society (IHSS). Results showed that the presence of O-containing functional groups (carbonyl in aldehydes and ketones, carboxyl in carboxylic acids, ester and ether groups) are in the order of compost > soil > lignohumate > lignite. Further, results of FTIR, fluorescence spectroscopy, and 13 C NMR suggested that samples of sodium humates isolated from soil, compost, and lignite were a more polycondensed, oxidized, unsaturated, humified, and aromatic structure. On the other hand, commercial lignohumate (LH) had very simple structural components and wide molecular heterogeneity. Furthermore, a small molecular size and weight, low degree of aromatic polycondensation, low level of conjugated chromophores and fluorophores, and low humification degree were characteristic for commercial LH. It should be noted that the sample of commercial LH was characterized by 13 C NMR analysis with a slightly higher value of aromaticity α in comparison with the sample of compost. The application of non-destructive analytical methods such as UV-VIS, FTIR, 13 C NMR, and fluorescence spectroscopy help us to provide main characteristics of selected humic substances.

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The content of organic matter in the soil, its labile (hot water extractable carbon–HWEC) and stable (soil organic carbon–SOC) form is a fundamental factor affecting soil productivity and health. The current research in soil organic matter (SOM) is focused on individual fragmented approaches and comprehensive evaluation of HWEC and SOC changes. The present state of the soil together with soil’s management practices are usually monitoring today but there has not been any common model for both that has been published. Our approach should help to assess the changes in HWEC and SOC content depending on the physico-chemical properties and soil´s management practices (e.g., digestate application, livestock and mineral fertilisers, post-harvest residues, etc.). The one- and multidimensional linear regressions were used. Data were obtained from the various soil´s climatic conditions (68 localities) of the Czech Republic. The Czech farms in operating conditions were observed during the period 2008–2018. The obtained results of ll monitored experimental sites showed increasing in the SOC content, while the HWEC content has decreased. Furthermore, a decline in pH and soil´s saturation was documented by regression modelling. Mainly digestate application was responsible for this negative consequence across all soils in studied climatic regions. The multivariate linear regression models (MLR) also showed that HWEC content is significantly affected by natural soil fertility (soil type), phosphorus content (−30%), digestate application (+29%), saturation of the soil sorption complex (SEBCT, 21%) and the dose of total nitrogen (N) applied into the soil (−20%). Here we report that the labile forms (HWEC) are affected by the application of digestate (15%), the soil saturation (37%), the application of mineral potassium (−7%), soil pH (−14%) and the overall condition of the soil (−27%). The stable components (SOM) are affected by the content of HWEC (17%), soil texture 0.01–0.001mm (10%), and input of organic matter and nutrients from animal production (10%). Results also showed that the mineral fertilization has a negative effect (−14%), together with the soil depth (−11%), and the soil texture 0.25–2 mm (−21%) on SOM. Using modern statistical procedures (MRLs) it was confirmed that SOM plays an important role in maintaining resp. improving soil physical, biochemical and biological properties, which is particularly important to ensure the productivity of agroecosystems (soil quality and health) and to future food security.

Bartlová J., Badalíková B., Pospíšilová L., Pokorný E., Šarapatka B. (2015): Water stability of soil aggregates in different systems of tillage. Soil & Water Res., 10: 147-154.The influence of various agrotechnical measures on macrostructural changes in topsoil and subsoil was studied in the course of a four-year experiment. Macrostructure was evaluated according to the ability of soil aggregate to resist degradation. Three variants of soil tillage were established: ploughing to a depth of 0.22 m, reduced tillage (subsoiling to 0.35-0.40 m, and shallow disking of soil to a depth of 0.15 m). For observation, three locations were chosen in various production areas of the Czech Republic with differing soil and climatic conditions. In these locations crops were grown under the same crop rotation: rapeseed (Brassica napus L.), wheat (Triticum aestivum L.), maize (Zea mays), wheat (Triticum aestivum L.), and barley (Hordeum vulgare). After four years of different tillage, a change in the water stability of soil aggregates (WSA) was evident. It was found out that reduced tillage of soil positively influenced both the WSA and the yield of the crops grown. A relationship of positive dependence between WSA, the content of humus substances, and cation exchange capacity of soil was also found. According to the obtained results, for agricultural practice a classification scale of structural quality was proposed on the basis of statistics of one variable (average, its mean error and distribution normality).

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