Recycling organic waste is most important for preserving natural resources. The research objective was to quantify the effect of the application of vermicompost and vermicompost leachate on the yield and quality of strawberries and compare it with a standard fertilization program with mineral fertilizers during a 3-year production cycle. Five fertilization treatments were studied: control—without fertilizer (Ø); vermicompost (V); vermicompost + foliar application of vermicompost leachate (VL); vermicompost leachate through fertigation and foliar application (L); and mineral NPK fertilizers (NPK). The application of V positively affected strawberry yield only in the first year. In all three years of fruiting, the highest yield was measured for NPK treatment. In the first year, fertilization had no effect on fruit quality, while in the second and third years, the application of leachate led to a significantly higher concentration of total soluble solids, total anthocyanins, antioxidant activity of the fruit, and a lower concentration of total acid. Strawberries are grown for a two- or three-year production cycle, so the application of V and VL cannot maintain the yield level as was with the application of mineral NPK fertilizers. The quality of strawberry fruit, however, can be improved significantly.

Thyme, mint, and lemon balm were used to determine whether shading conditions could improve the yield, composition, antioxidant, and antimicrobial activity in plant essential oils (EOs) in comparison with non-shaded plants from an open field. The yield of the EOs of non-shaded thyme, mint, and lemon balm, was 3.44, 3.96, and 0.21 mL/100 g, respectively. Plants covered by nets produced different levels of EOs (3.46, 2.20, and 0.45 mL/100 g) after 120 min of hydrodistillation. The main components of the thyme essential oil are thymol (44.2–43.9%), γ-terpinene (18.3–16.8%), and p-cymene (16.5–17.4%). The predominant components of mint essential oil are piperitenone oxide (52.6–64.8%) and 1,8 cineole (25.9–16.3%), while lemon balm essential oil consists of the following main components: geranial (34.0–32.8%); neral (21.3–24.9%); and piperitenone oxide (17.2–16.7%). The EOs from non-shaded thyme and mint plants have the highest antioxidant activity (EC₅₀ value 0.54 mg/mL and 3.03 mg/mL). However, shaded lemon balm showed a stronger antioxidant activity (EC₅₀ 3.43 mg/mL) than non-shaded plants (12.85 mg/mL) after 60 min of incubation. The EOs from all plants showed significant effects against Escherichia coli, Proteus vulgaris, Bacillus subtilis, Staphylococcus aureus, and Candida albicans. The most active EOs against most of the isolates originated from Thymus vulgaris L., plants. Adequate cultivation techniques, such as shading for Lamiaceae plants, has positive effects, especially in Melissa officinalis L. Shading can achieve a higher content and components in terms of the specific biological activity (antioxidant and microbial) of EOs.

Digestate is a residue of the anaerobic decomposition of organic waste for biogas extraction, but it can be reused as a source of nutrients. To examine the effect of digestate in kohlrabi production, field experiments were conducted during three seasons in two calendar years. The fertilization treatments included the application of solid digestate (two rates—DS1 and DS2), liquid digestate (two rates—DL1 and DL2), solid manure (two rates—MS1 and MS2), and mineral fertilizer (NPK) and were compared with a plot without fertilization (Ø). The results showed a significant increase in the yield with the use of solid and liquid digestate, as well as with NPK, in all growing seasons, while the microelement contents (Zn, Mn, and Cu) in the leaves were at optimum level. The applied treatments did not increase the plant-available nutrients (AL-P₂O₅, AL-K₂O, Fe, Cu, and Zn) in the soil (except Mn). The application of DL2, MS1, and MS2 led to a higher Pb content in kohlrabi stems compared to the control, but the Pb content remained below the maximum permitted limit. Our research showed that digestate can be used as a valuable source of nutrients for kohlrabi production, with a low risk of soil and plant contamination by heavy metals. However, the control of soil, digestates, and manure quality is recommended.

Context: Biofortification of forage crops has become even more important, due to the improvement in livestock nutrition, but it has also had an indirect positive impact on the human diet. Aim: This study investigated the effect of nitrogen and microelement (Zn and Se) fertilisation on yield and on the microelement composition of maize (Zea mays L.) silage. Methods: Two field experiments were conducted using a two-factorial split-plot design with nitrogen fertilisation in three doses: 0, 120, 180 and 240 kg N/ha. The first experiment included foliar Zn fertilisation as the second factor (0, 1.5 kg Zn/ha and 1.5 kg Zn/ha + urea solution). The second experiment studied the effect of Se (10 g Se/ha). Key results: Nitrogen fertilisation increased biomass yield, Cu and Mn concentration in silage maize. Application of Se and Zn did not affect the biomass yield, but it had a positive effect on Se and Zn concentration in plants. Zn and urea application in combination proved to be more efficient in increasing Zn concentration in plants when compared to Zn applied alone. Conclusions: Nitrogen and fertilisation with Zn and Se can be a good tool in fodder plant biofortification because their application led to a yield increase (Zn), but at the same time to an improvement in the mineral composition of maize biomass, with essential elements (Zn and Se). Implications: Although biofortification with 1.5 kg Zn/ha has achieved the concentration in maize biomass that can meet the nutritional needs of dairy cows, further research is needed to examine the adjuvant doses and forms of Zn to obtain high yields and Zn concentration in forage crops.

The rising cost of mineral fertilizers and the decreasing availability of manure in vegetable farming highlight the need for alternative fertilization strategies. To examine the possibility of applying byproducts from the food processing industry, sugar beet molasses, and compost from brewery sewage sludge in celery production, the field experiment was conducted over two years, using a randomized complete block design with three replications. The examined variants were T0—control (without fertilizer); T1—mineral fertilizer; T2—cattle manure; T3—sheep manure; T4—poultry manure; T5—supercompost; and T6—molasses. In the first year, there was no significant difference between T1 and T5 in thickened root yield, while these two variants achieved significantly higher yield compared with other variants. In both years, the highest leaf yield was achieved with T1, while no significant difference was found between T5, T6, and conventional organic fertilizers of animal origin. The highest amount of N was absorbed by roots in T1 (42.0 kg/ha and 51.2 kg/ha, respectively), while the lowest amount was absorbed in T0 (25.5 kg/ha and 26.7 kg/ha, respectively). A significantly higher amount of P₂O₅ was absorbed by roots in all organic fertilizer variants compared to T0 and T1. In both years, of all the nutrients, K₂O was the most absorbed nutrient by the celery root, while CaO was absorbed in greater quantities than N. Based on two years of research, it can be concluded that compost from brewery sludge and sugar beet molasses can be used as an alternative source of nutrients for plants.