Effect of Fertilization and Plant Density on the Nutritional Value of Nettle (Urtica dioica L.)

Stinging nettle (Urtica dioica L.) is a multipurpose perennial plant with growing interest as a source of nutrients for both human and animal consumption. Despite its recognized nutritional potential, limited research has addressed how agronomic practices influence its nutritional quality. The aim of the present study was to assess the effects of plant density and fertilization on the micro- and macronutrient content of nettle plants and seeds. A three-year field experiment (2021–2024) was conducted under Mediterranean conditions using a split-plot design with two plant densities (12 and 16 plants m−2) and three nitrogen fertilization regimes [control (0 kg N ha−1), urea (200 kg N ha−1), and urea with urease inhibitor (200 kg N ha−1)]. Results showed that nitrogen fertilization significantly affected macronutrient composition, increasing crude protein and crude carbohydrates (by up to 6% and 4% respectively) while reducing crude fat and fiber contents by up to 10% in nettle plants. However, fertilization negatively influenced the concentrations of Mg, Zn, K, and Mn in seeds and reduced their content by up to 16%, 4%, 9%, and 5% respectively. On the contrary, Fe and Cr increased under nitrogen application. Plant density had a minor effect on nutritional content, mainly improving protein accumulation in lower densities. Overall, U. dioica demonstrated a stable nutritional profile and high mineral content, therefore supporting its potential as a sustainable dual-purpose crop for food and feed systems. The findings of the present study indicate that proper crop management can significantly improve the nutrient content of nettle plants and seeds.