With growing interest in the broader use of medicinal and nutritionally valuable plant parts, attention is expanding beyond the fruit of honeysuckle (Lonicera caerulea L.) to include other organs such as leaves. These leaves constitute a valuable source of bioactive substances and essential minerals. This study aimed to evaluate the effect of zoocompost derived from black soldier fly (Hermetia illucens L.) larvae on the macrominerals of honeysuckle leaves.

A field experiment was conducted in the Alytus district of Lithuania, involving three cultivars: ‘Zojka’, ‘Wojtek’, and ‘Indigo Yum’. Plots were arranged in a randomized design with four replicates. Zoocompost was applied at 0 (control), 1000, 1500, and 2000 kg ha⁻¹ at the end of March. Leaf samples were collected in mid-July, freeze-dried, and analyzed for nitrogen (N) using the Kjeldahl method. Phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) were determined by means of inductively coupled plasma atomic emission spectrometry (ICP-AES). Soil samples collected in June were analyzed for available P₂O₅, K₂O, mineral nitrogen, and pH.

The leaf sample results showed that N content was significantly highest in ‘Zojka’ leaves treated with 1500 kg ha⁻¹ of zoocompost, while the highest P content was recorded in the same cultivar at the 2000 kg ha⁻¹ application rate. The ‘Indigo Yum’ treated with 2000 kg ha⁻¹ showed significantly increased Ca content but significantly lower K content. The lowest Ca content was observed in ‘Zojka’ leaves under the 2000 kg ha⁻¹ treatment. No significant effect was found on Mg levels. Application of zoocompost at the highest fertilization rate significantly increased the contents of available P₂O₅, K₂O, and mineral nitrogen in the soil. Fertilization did not have a significant effect on soil pH.

The results of this study demonstrate that zoocompost can effectively improve both the macromineral composition of honeysuckle leaves and soil fertility by increasing the availability of key nutrients.