Suitability of the vegetation indices of normalized difference vegetation index (NDVI), blue normalized difference vegetation index (BNDVI), and normalized difference yellowness index (NDYI) obtained by means of UAV at the flowering stage of oil seed rape for the prediction of seed yield and usability of these vegetation indices in the identification of anomalies in the condition of the flowering growth were verified based on the regression analysis. Correlation analysis was performed to find the degree of yield dependence on the values of NDVI, BNDVI, and NDYI indices, which revealed a strong, significant linear positive dependence of seed yield on BNDVI (R = 0.98) and NDYI (R = 0.95). The level of correlation between the NDVI index and the seed yield was weaker (R = 0.70) than the others. Regression analysis was performed for a closer determination of the functional dependence of NDVI, BNDVI, and NDYI indices and the yield of seeds. Coefficients of determination in the linear regression model of NDVI, BNDVI, and NDYI indices reached the following values: R² = 0.48 (NDVI), R² = 0.95 (BNDVI), and R² = 0.90 (NDYI). Thus, it was shown that increased density of yellow flowers decreased the relationship between NDVI and crop yield. The NDVI index is not appropriate for assessing growth conditions and prediction of yields at the flowering stage of oil seed rape. High accuracy of yield prediction was achieved with the use of BNDVI and NDYI. The performed analysis of NDVI, BNDVI, and NDYI demonstrated that particularly the BNDVI and NDYI indices can be used to identify problems in the development of oil seed rape growth at the stage of flowering, for their precise localization, and hence to targeted and effective remedial measures in line with the principles of precision agriculture.

The effect of coating the seed of clover crops by water absorbing seed process (WASP) technology pelletization on its germination capacity was studied in conditions of diverse drought intensities simulated by different concentrations of polyethylenglycol (PEG) 8000 solution. Drought resistance was monitored in the seed of five fodder clover species: Anthyllis vulneraria L., Medicago lupulina L., Trifolium repens L., Melilotus albus Medik. and Onobrychis viciifolia Scop. In the seed of given plant species, germination capacity was determined along with the share of dead and hard seeds. Although the coating significantly (p < 0.05) affected the drought resistance of seeds, the germination capacity increased only in conditions of milder drought (simulation with PEG: 0.1–0.3 mol). With the increasing intensity of drought induced by higher PEG concentrations (0.4–0.7 mol) the number of germinable seeds demonstrably decreased and the number of dead seeds increased in the coated seed as compared with the uncoated seed. The coated seed can be appropriate for use in M. lupulina, M. albus and T. repens, while the uncoated seed can be used in A. vulneraria and O. viciifolia.

The ever-growing number of biogas plants also leads to an increasing demand for suitable, alternative plant substrates. A currently dominant plant substrate is maize silage. However, intensive cultivation of maize (Zea mays L.) as an energy crop in monocultures poses risk to the environment (soil erosion, depletion of soil nutrient supplies, increased concentration of pests—Ostrinia nubilalis). In this study, results of experimental methane production from silages of alternative substrates, such as fodder mallow (Malva verticillata var. crispa L.; FM), white sweet clover (Melilotus albus Medik.; WSC) and their mixture, are presented. Based on the dry matter yield of a mixed culture of mallow and sweet clover, the value of the land equivalent ratio parameter (LER) was set as 1.05. The obtained LER (>1) value shows that the cultivation of the two tested crops in the mixed culture is more beneficial than their monocultures. Methane production from all three silage variants was fully comparable with results of methane production from the maize silage. Anaerobic fermentation of the mixture of FM and WSC did not result in higher methane yield than the average result of monosubstrates.

Legume cultivation, especially the clover species, has shown promoting effects on soil biological properties. However, the ways in which various clover species contribute to beneficial plant-rhizosphere soil interactions have remained neglected in the past. Therefore, we performed a field experiment to assess and compare the species-specific influence of five different clover species on plant traits, microbial soil health indicators, namely soil enzymes, microbial biomass and abundance and their potential nutrient cycling abilities under rhizosphere and non-rhizosphere soils. For this, soil samples from bulk soil and rhizosphere of each clover species were collected and analyzed for soil enzymes including β-glucosidase, arylsulfatase, phosphatase, N-acetyl-β-D-glucosaminidase, and urease and microbial communities’ abundance. Results revealed that the soil biological properties were more affected in the rhizosoil than in the bulk soil, although the individual legume crop variants differed in the rate and extent of the differential impact on either rhizosoil or bulk soil. The most significantly affected species-specific properties were ammonium oxidizing bacteria and phosphorus-solubilizing microbiota in the rhizosoil of white clover and alsike clover variants, whereas the least impact was exerted by sweet clover. The biological properties of rhizosoil showed a significant effect on the plant qualitative and quantitative properties. We further detected antagonism among N and P + K transfer from the rhizosoil to plants, which influenced above ground and root biomass. Overall, these results suggest that the positive effects of clover species cultivation on rhizosphere soil properties are species specific.

The presented paper deals with the testing of a possibility to reduce emissions of undesirable greenhouse gases (CH₄, CO_2; NO_x) and their mixture (biogas) during the storage of digestate using applications of secondary plant metabolites (tannins). The experiment was conducted in laboratory conditions in which the digestate was placed in fermentation chambers. Prior to the fermentation process, preparations were applied to the digestate, which contained tannins: Tanenol Antibotrytis (TA), Tanenol Clar (TC) and Tanenol Rouge (TR) in three concentrations (0.5, 1.0 and 2.0% w/w). The application of these preparations demonstrably affected the production of biogas and the contents of CH₄, CO₂ and N therein. The application of TR preparation in the concentration of 1.0% and 2.0% significantly reduced the production of biogas as compared with all variants. The preparation further inhibited the process of CH₄ development. In contrast, the other preparations with the content of different kinds of TA and TC increased the production of biogas (on average by 15%), CH₄ (on average by 7%) and CO₂ (on average by 12%) as compared with the control variant and TR variant. These two variants reduced the concentration of N in biogas on average by 38%. Thus, the tested Tanenol tannin preparations can be used in different concentrations either to control emissions of greenhouse gases during the storage of digestate or, in case of increased production of CO₂ for its reuse in order to increase methane yields in the process of anaerobic fermentation.

The presented study deals with the use of legumes intercropped with maize for the production of biogas from silage. The main goal was to find out whether silages made from mixed cultures can be used in biogas production and how the use of such silages affects qualitative and quantitative parameters of the fermentation process compared with the pure maize silage. Variants prepared were pure cultures of maize, bean, lupin, and white sweet clover. In addition, mixed cultures were prepared of maize and individual legumes. Measured values showed that in terms of dry matter (DM) yield, mixed culture silages are almost of the same or even better quality than silage made from the maize monosubstrate. Compared with the maize monoculture silage, the presence of white lupine, white sweet clover, and broad bean in silages statistically significantly increased the content of DM, ash, and acid detergent fiber (by more than 5%). Bean and lupine in mixed silages with maize significantly increased the content of lipids (on average by more than 1.2%). Legumes in silages were significantly decreasing contents of neutral detergent fiber, crude protein, and starch. Production of biogas from silages of maize monosubstrates and mixed substrates of maize with white lupin, maize with white sweet clover, and maize with broad bean was directly proportional to the content of CAR and starch in these substrates. A perspective variant was the mixed substrate of maize and sweet clover from which biogas production was only 6% lower than that from conventional maize silage. The highest yield was recorded in the maize monosubstrate (0.923 m³/kg_VS). Variants of mixed substrates had a yield ranging from 0.804 to 0.840 m³/kg_VS.