Urease and nitrification inhibitors represent ways to reduce nitrogen losses; their presence modifies microbial and enzymatic activity in the soil, affecting pH and organic matter (OM), which in turn affects the mobility of heavy metals. To evaluate the effect of urea with inhibitors, pH, OM content, and pseudo-total and mobile metal content (Cu, Cd, Ni, Pb, Cr, Zn, and Mn) were determined in soil samples fertilized with six different urea variants with inhibitors. The modification in the pseudo-total content of heavy metals following fertilization (%) was as follows: Cu (−39.26 ÷ −8.82), Cd (10.74 ÷ 15.40), Ni (5.76 ÷ 18.84), Pb (−13.30 ÷ 12.46), Cr (−15.55 ÷ 11.60), Zn (35.10 ÷ 162.76), and Mn (−1.32 ÷ 12.17). The pH was situated in the range of 7.05 to 7.17, while OM content showed an average increase of 16%. The determined pollution indicators revealed an accumulation of Zn in the soil. The results showed a trend of accumulation of bioavailable heavy metals, with the greatest increase for Mn (43%). Only in the case of Zn, there was a decrease in mobile content with the lowest value when applying two urease inhibitors and one nitrification inhibitor. Inhibitors modify the OM content and soil pH, influencing the mobility and bioavailability of heavy metals.

Bee venom is a complex natural beekeeping product, traditionally used in apitherapy, with a wide spectrum of pharmacological properties. Research on the mineral content of bee venom is limited and challenging to compare across studies due to the varying regions where they are conducted. Our study aimed to assess the mineral content of bee venom and how supplementary feeding of bee colonies with probiotic products, essential oils, as well as rapeseed and acacia nectar and pollen, affects the mineral content and antioxidant activity of the venom. The parameters analyzed included moisture, pH, dry matter, ash, impurities, and levels of macro and micro elements and antioxidant activity. The moisture content of the samples was 10–22%, and pH ranged between 5.84 to 6.41. The macro element content of the venom showed that potassium was the most abundant macro element, followed by calcium, magnesium, and phosphorus. Pb was identified in samples collected indicating lead pollution in the area where the hives were located in the case of the three harvests. In all samples, the highest DPPH radical scavenging activity was observed at a concentration of 2.00 mg/mL, with sample V6 showing the maximum value of 87.05%.

Research Journal of Agricultural Science

Efficient nitrogen (N) management is essential for improving nitrogen use efficiency (NUE) while reducing environmental N losses in wheat production. A two-year field experiment (2023–2024) evaluated six urea formulations containing urease (UI), nitrification (NI), or combined inhibitors for their effects on soil nitrogen transformations, fertilizer N retention, and wheat productivity in a Cambic Chernozem under temperate conditions. Six fertilization treatments were compared: conventional urea (U1), urea with one NI (U2), two UIs (U3), one UI (U4), one UI plus one NI (U5), and two UIs plus one NI (U6). U1 produced the greatest early-season nitrate accumulation (153.4 mg kg⁻¹), whereas fertilizers containing NI reduced nitrate formation and prolonged ammonium availability. The combined formulation containing two UIs and one NI (U6) exhibited the highest and most persistent nitrification inhibition (70.3% at stem elongation), indicating effective regulation of soil N transformations. Although fertilizer N retention declined during crop development in all treatments, U6 produced the highest grain yield (6417 kg ha⁻¹), while U2 achieved the highest grain protein concentration (12.64%). Across both growing seasons, inhibitor-containing fertilizers consistently outperformed conventional urea by improving the synchronization between nitrogen release and crop demand. These findings demonstrate that combining urease and nitrification inhibitors enhances nitrogen use efficiency, sustains wheat productivity and grain quality, and represents a promising strategy for more sustainable nitrogen management under temperate agroecosystem conditions.