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.

Digestate contains many valuable nutrients, including nitrogen (N), phosphorus (P), and potassium (K); however, it is characterized by relatively little organic matter. The objective of this study was to assess the four-year impact of digestate (Dig) application, digestate + straw (Dig + St), cattle slurry (Csl), and mineral fertilization (NPK) on soil organic carbon (SOC), total nitrogen (TN), mineral N (N_min), and the content of plant-available P and K. Fertilization did not have any significant influence on SOC, TN, and SOC/TN parameters. Yet, in comparison with control, there was an upward trend in the concentration of SOC and TN in the topsoil, where fertilizers were applied. In contrast to SOC and TN, fertilizer treatment significantly affected the content of P, K, and N_min, and the differences depended on the soil depth and the fertilizer used. On average, the highest content of P was obtained in Csl treatment, but the highest content of K was observed in Dig + St. The effect of treatment on N_min in spring was as follows: NPK = control < Csl = Dig + St < Dig. Straw plowing increased the bio-immobilization of N with digestate and, at the same time, lowered the content level of nitrates in soil.

Fertilization is a key factor for sustaining productivity in agroecosystems. A long-term experiment in cambisol following periodical application of several types of fertilization has been running at the experimental site since 1954. In this study, we determined the impact of applied inorganic and/or organic fertilizers on the activity of soil enzymes and on the structure of microorganisms at depths of 0–30 cm and 30–60 cm. Single-factor comparison showed that use of inorganic and/or organic fertilizer had an insignificant effect on the activities of soil enzymes (at depths 0–30 cm and 30–60 cm) and also on the structure of microbial communities at both depths studied. Only soil respirations exhibited stimulation by combined fertilization. The results, irrespective of sampling depth (0–60 cm), showed that application of combined organic and inorganic fertilization stimulated the activity of glucosidases and use of inorganic fertilizer inhibited the activity of arylsulphatases. Respirations were stimulated by application of organic fertilizer and combined fertilization. Nevertheless, principal component analyses, which calculate with multidimensional data, revealed differences in samples treated by sole mineral fertilizer compared to other variants, especially in the lower layer. In general, our results indicate that use of combined fertilization may improve biological characteristics in deeper parts of soil profile and possibly increase biological activity in agroecosystems.

Digestate represents an alternative source of nutrients for crops in sustainable agriculture. We aimed to evaluate the effects of digestate fertilization on grain (GY) and straw yield (SY) and nutrient content and uptake in winter wheat (WW) and spring barley (SB). The study duration was from 2012 to 2016, with the following crop rotation: WW/WW/SB/WW. Every year, the same fertilizers were applied to each respective plot: control, digestate, digestate + straw, cattle slurry, and mineral NPK fertilizer. Significantly higher GY and SY were noted after fertilizer application each year compared to the non-fertilized control. The average effect of the fertilizers on GY of WW was control < NPK ≤ digestate + straw ≤ cattle slurry ≤ digestate. Fertilizer application also increased N, S, Na, Zn, and Fe content in the grains, especially when digestate was used as fertilizer. However, in non-fertilized plants (control), only the K content increased in the grains, although the uptake of K is positively correlated with GY. Our results show that digestate can be used not only as a replacement for cattle slurry but also as an alternative fertilizer, which, under certain soil conditions, is more effective than NPK fertilizer.

In order to recommend the dose of fertilization for sugar beet under currently unstable weather conditions, we analysed beetroot and top yields, sugar content (SC), and the effect of fertilization on soil chemistry over a three-year period (2016–2018). All three years were characterized by different weather conditions. The year 2016 was very warm and very dry. The year 2017 was warm with normal precipitation. The year 2018 was extraordinary warm and very dry. We compared the following ten fertilization treatments: unfertilized control, farmyard manure (FYM), mineral fertilizers NPK1–4, and FYM + NPK1–4. The applications of FYM, NPK, and FYM + NPK resulted in significantly higher yields of beetroots and tops as compared with the control, while no significant differences were recorded among FYM, NPK, and FYM + NPK treatments. The SC was not affected by the fertilization. The application of NPK resulted in a lower pH value, while the highest values were recorded for the control and FYM treatments. The application of FYM + NPK increased the content of organic carbon (Corg) in the soil, the total content of nitrogen (Ntot), and P and K concentrations. According to the results of the linear-plateau model, the recommended dose of N is 112 kg ha⁻¹, corresponding to a beetroot yield of 66 t ha⁻¹.

Farmers must adapt to the changes brought about by the changing climate and market requirements. These adaptations are associated with fertilization—the availability of organic manures and mineral fertilizers and crop rotations. What is the effect of organic manures on wheat and soil? Is it necessary to apply mineral phosphorus P and potassium (K) fertilizers to the wheat? These questions are frequently asked in workshops in different growing areas. To provide a relevant answer on this issue, we evaluated how farmyard manure (FYM), mineral nitrogen (N) applied without phosphorus (P) and potassium (K) fertilizers, and application of NPK affected grain yield, grain quality, and soil properties under different soil-climate conditions (Ivanovice—Chernozem, Caslav—Phaeozem, Lukavec—Cambisol) between 2015 and 2018. The FYM significantly increased grain yield even after three years since being applied and incorporated into the soil in all localities, but its application didnot affect grain quality. In the soil, the FYM significantly increased total nitrogen Nt, P, and K content in all localities and oxidable carbon Cox content in two localities. Mineral nitrogen significantly affected grain yield and quality and increased concentrations of soil N and C, but decreased pH in Caslav. Application of mineral P and K wasnot connected with a positive effect on grain yield and quality, but increased the concentration of these elements in the soil, preventing depletion of these elements from the soil. Maximal yields were recorded when 70–98 kg N ha⁻¹ was applied in Ivanovice, 55–72 kg N ha⁻¹ in Caslav, and 155 kg N ha⁻¹ in Lukavec.