Municipal green-waste compost and wheat straw biochar amendments were assessed for their assistance in regulating the mobility of Cu, Pb, Zn, Cd, Cr and Ni and the uptake of these metals by five commonly grown green leafy vegetables (radish, lettuce, dill, spinach and parsley). The amendments were applied alone or combination of both in 5% and 10% (v/w) doses to soil contaminated with heavy metals. Vegetables were grown for eight weeks under greenhouse conditions, and in collected samples plant uptake and metal speciation in soil after sequential extraction procedure (BCR) were analyzed by Microwave Plasma Atomic Emission Spectrometer (MP-AES). The results of our study show that organic amendments noticeably reduced the uptake of heavy metals by various leafy vegetables, with the best result of reduced leaf accumulation for single biochar and biochar–compost mix application at higher dose. Single application of green-waste municipal compost may have adverse effects on heavy metal uptake, increasing the risk of vegetable contamination with Zn, Pb and Cr. This study recommends careful selection of vegetables for cultivation when organic fertilizers are applied to soil with elevated contents of trace elements or co-application of compost in mix with biochar to mitigate possible negative effects and human health risk.

This study aimed to examine the influence of long-lasting moderate (45% field water capacity—FWC) and severe (30% FWC) water stress and application of sulphur (elemental sulphur or sulphate) on the growth, yield and mineral composition of wheat and maize. Concentrations of macro- and micronutrients were determined in the aboveground parts of the plants. Drought stress caused a marked decrease in the growth parameters of both plants. Under both optimal water conditions (60% FWC) and moderate water stress (45% FWC), grain yields of wheat grown without sulphur application were not significantly different. Applying elemental sulphur caused an increase in grain yield under moderate stress, whereas sulphate was more effective in wheat grown under adequate water supply. Severe water stress significantly lowered wheat yield, regardless of sulphur fertilisation. Increasing water stress resulted in a greater reduction in maize growth, with an average 50% decrease in dry mass under severe water stress. Both crops maintained relatively high levels of macro- (N, P, K, Mg, Ca, S) and microelements (Mn, Fe, Cu, Zn) and did not suffer noticeably from deficiencies in such. Sulphur application did not modify these relationships. In conclusion, sulphur fertilisation may be recommended in wheat cultivation when plants are exposed to moderate water stress.

Water and nutrient deficiencies in soil are becoming a serious threat to crop production. Therefore, usable water and nutrient recovery from wastewater, such as urine and grey water, should be considered. In this work, we showed the possibility of using grey water and urine after processing in an aerobic reactor with activated sludge in which the nitrification process takes place. The resulting liquid (nitrified urine and grey water, NUG) contains three potential factors that can adversely affect plant growth in a hydroponic system: anionic surfactants, nutrient deficits, and salinity. After dilution and supplementation with small amounts of macro- and micro-elements, NUG was suitable for cucumber cultivation. Plant growth on this modified medium (enriched nitrified urine and grey water, NUGE) was similar to that of plants cultivated on Hoagland solution (HS) and reference commercial fertilizer (RCF). The modified medium (NUGE) contained a significant amount of sodium (Na) ions. Therefore, typical effects of salt stress were observed in cucumber plants, including reduced chlorophyll levels, slightly weaker photosynthesis parameters, increased H₂O₂ levels, lipid peroxidation, ascorbate peroxidase (APX) activity, and proline content in the leaves. In addition, reduced protein levels were observed in plants treated with recycled medium. At the same time, lower nitrate content in tissues was found, which may have resulted from their intensive use by nitrate reductase (NR), the activity of which significantly increased. Although cucumber is a glycophyte, it grew very well in this recycled medium. Interestingly, salt stress and possibly anionic surfactants promoted flower formation, which in turn could positively affect plant yield.

Struvite is regarded as a promising phosphorus (P) fertilizer compared to commercial pristine mineral phosphorus fertilizers. The aim of this study was to determine the effect of Phosgreen fertilizer, with struvite as its phosphorus source, on the chlorophyll, potassium (K), and calcium (Ca) contents in lettuce grown in peat compared to superphosphate. The study was carried out as a pot experiment with different doses of P fertilization. The study presents the chlorophyll a, b, total (a + b) chlorophyll, and carotenoid contents of the lettuce plants. Significant differences in the chlorophyll a and b contents were observed between the different phosphorus applications, and this can have a direct impact on the crop yields. Significantly higher contents of both chlorophyll contents were observed under Phosgreen fertilization as well as the chlorophyll a + b content *. The results of the study on lettuce indicate a dependence of vitamin C content on phosphorus fertilizer, but with no significant increase under Phosgreen fertilization; the contents of K and Ca were not significantly dependent on the type of phosphorus fertilizer. Due to the favorable composition of Phosgreen, it may be recommended for use as a phosphorus fertilizer in the agriculture and horticulture sectors.

Previous research indicated the potential use of struvite (STR) as an alternative source of phosphorus (P) in crop production. A greenhouse experiment was conducted to evaluate the effect of STR and triple superphosphate (TSP) on the growth and chemical composition of butterhead lettuce grown on peat substrate over a three-month period (May–July). Both alternative (STR) and conventional (TSP) fertilizers were applied at three rates: (1) recommended rate based on the elemental content of substrate and crop nutritional need; (2) reduced rate (50% lower than recommended); and (3) increased rate (50% higher than recommended). Unfertilized (control) plants were also grown in the pot experiment. As expected, fertilizer application tended to increase the content of heavy metals in the substrate. Thus, an increase in Zn, Pb, and Cu content in peat substrate was found following STR amendments. However, compared with unfertilized plants, the applied rates of the STR and TSP fertilizers did not increase the content of Cd and Cu in the plant leaf, while Hg content was below the detection limit. In addition, Zn content in the plant leaf significantly decreased following STR and TSP applications. In comparison to unfertilized plants, both alternative and conventional fertilizers increased the content of P and nitrate nitrogen (N-NO₃⁻) in the plant leaf while their effect on Mg content was negligible. The increased rate of STR was the best fertilizer treatment because it produced the largest number of leaves, which were also characterized by the highest P content. Our findings showed that STR was an effective source of P in butterhead lettuce cultivation without adverse effects on heavy metal accumulation.

In the experiment, the impact of magnetisation on cucumber seeds is examined with the use of Bitter magnets with a constant magnetic field. The magnetisation process is performed in three magnetic fields: low—200 mT, medium—1 T, and high—9 T for 15 and 60 min. After germination, the biometric parameters are determined. The results of this research show that cucumber after pre-treatment in a magnetic field of 1 T for 60 min has a similar germination capacity and root length as the control sample. However, cucumber seeds magnetised in a 1 T field for 60 min have a significantly higher dry weight than the control sample (5.50 ± 0.32 mg vs. 3.01 ± 0.18 mg). The magnetisation in 9 T for both 15 and 60 min shows that these samples have a significantly lower germination capacity (86.8 ± 4.4% and 81.4 ± 7.3% vs. 91.8 a ± 3.2%) and root length (1.78 ± 0.02 cm and 4.42 ± 0.83 cm vs. 8.21 ± 0.34 cm) compared to the control sample. The cucumber seeds pre-treated at 9 T have a significantly greater dry weight than the control sample. Additionally, our research shows that some magnetic field intensities and magnetisation durations inhibit root growth and limit germination. These results are also important as they indicate which values of magnetic fields should be avoided.