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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. [ABSTRACT FROM AUTHOR]

Cultivation of energy crops is a part of modern agriculture. In particular, maize (Zea mays L.) is widely grown in central Europe. However, in terms of erosion risk and high demands on fertilization and protection against diseases and pests, its growing is not environmentally friendly. Therefore, possibilities of utilization of other more environmentally friendly energy crops have been examined at present. The aim of the study was to evaluate the effects of various fertilization (mineral, digestate, control) on the yields of tall wheatgrass (TWG) (Elymus elongatus subsp. ponticus) and reed canary grass (RCG) (Phalaris arundinacea L.) cultivated in a long-term field experiment on the experimental site in Czech Republic. The energy profit from cultivation of these crops and its protective anti-erosion effect were evaluated. The average yields ranged from 4.6 (RCG, mineral fertilization) to 7.4 t/ha (TWG, digestate fertilization). The more profitable species was tall wheatgrass, the biomass of which also had the higher heating value. The energy profit ranged from 80 GJ/ha (RCG, control variant and mineral fertilization) to 133 GJ/ha (TWG, digestate and mineral fertilization). It has been found that the tested plants excel in anti-erosion effect and could therefore be a suitable alternative to maize, especially in less-favored areas. [ABSTRACT FROM AUTHOR]

Environmental friendly agricultural management has an urgent need for finding a sustainable strategy for the usage of different by-products from bioenergy production. These are either used as soil amendments or fertilizers. This study is aimed at evaluating if and how soil organic matter changes after the application of biochar, compost, and digestate. A pot experiment was conducted with Haplic Cambisol (low range arable soil) in Phytotron CLF PlantMaster (Wertingen, Germany). The chemical composition of isolated humic acids (HA) was determined by an inductively coupled plasma-mass spectrometer (ICP-MS). FT-IR spectroscopy and CHNS analysis were used for detailed chemical and optical characterization. Soil magnetic properties - radical concentration, g-parameters of radicals, and iron ions were evaluated by EPR spectroscopy. The results showed that amending arable soil with biochar, digestate and compost results in chemical and structural changes of humic substances. The radicals originated in biochar and digestate are built-in to the structure of the humic acid, which was confirmed by EPR g-parameter values. Despite a relatively high concentration of paramagnetic metal ions Fe and Mn the effect of semiquinone radical quenching was not observed. That suggests a conclusion that metal ions of studied amendments are binding in HA structure and did not disturb natural radical processes in the soil. It was also concluded that the effect of applied material depends mainly on its chemical properties and the soil type. [ABSTRACT FROM AUTHOR]