This study investigated copper accumulation and pesticide residue patterns in agricultural soils under four cropping systems (stone fruit, olive, grapevine and potato) in Zadar County, Croatia. Soil samples were taken before and after the growing season. Copper concentrations were determined by ICP-MS after microwave digestion. A total of 453 pesticide-active compounds were analyzed using available standards by LC–MS/MS and GC–MS/MS after a modified QuEChERS extraction. The highest copper concentration was found in stone fruit soils (34 mg kg ⁻¹ ) and the lowest in vineyards (25.9 mg kg ⁻¹ ). After the growing season, there was a significant increase in copper concentration in stone fruit ( p = 0.020) and vineyard soils ( p = 0.018), with individual values reaching 290 mg kg ⁻¹ . Alarmingly, 30% of the samples from olive groves exceeded the critical copper limit of 100 mg kg ⁻¹ . Copper levels increased after the season in up to 90% of the plots, indicating widespread accumulation. Pesticide residues varied by crop and season. The fungicide boscalid was prevalent in vineyard soils before the season, but decreased after, while fludioxonil, tebuconazole and fluopyram increased. Difenoconazole was present in all crop soils, most prevalent in potatoes. Insecticides such as omethoate, thiamethoxam and chlorpyrifos were found in all locations, with thiamethoxam increasing in potato soils despite its legal ban. Pendimethalin was the most widely used herbicide. These results show considerable crop- and season-specific contamination patterns and emphasize the need for sustainable pesticide use, soil monitoring, and targeted strategies to protect soil and ecological integrity in Mediterranean agroecosystems.

The cultivation of sweet cherry takes place in various climatic zones, where the plant may be exposed to different types of environmental stress during the growing season, which can significantly affect yield and fruit quality. The role of various physiologically active compounds is crucial for plant resistance to stressful environmental conditions. The aim of this study is to determine how the foliar application of different physiologically active substances affects the mineral composition of sweet cherry leaves. Research was performed in 2022 and 2023 at two locations (Ninski Stanovi and Murvica) in Zadar County with the Regina variety. The trials included five foliar treatments (T0—water only, T1—Ca nutritional supplement, T2—biostimulant (Ascophyllum nodosum L.), T3—proline solution, T4—salicylic acid solution). Leaf samples were collected for the analysis of the following macro-elements: total carbon (TC), total nitrogen (TN), calcium (Ca), magnesium (Mg), potassium (K), and phosphorus (P). On average, significantly higher TN content in leaves was found only in T2 (15% higher than T0). Ca, Mg, and K contents in leaf dry matter in all variants were higher by 20–29%, 13–20%, and 12–14%, respectively, compared to the control variant. The significant correlations were found between Ca and Mg, Ca and P, as well as Ca and K contents. This study shows a significant impact of the applied compounds on sweet cherry leaf mineral composition, and considering the year and locality effects, further testing of these treatments in different environments could be suggested.