Intercropping Strategies to Maintain Crop Productivity under Reduced Nitrogen Fertilization in Mediterranean Horticultural Systems

Intercropping strategies represent a promising agronomic approach to improve nitrogen (N) use efficiency and reduce fertilizer inputs in intensive horticultural systems. This study evaluated the capacity of intercropping systems to maintain crop productivity under reduced nitrogen fertilization in Mediterranean conditions.

Field experiments were conducted during the 2025 growing season using broccoli (Brassica oleracea var. italica) and watermelon (Citrullus lanatus) as model crops. Optimal nitrogen fertilization rates were established for each crop and subsequently reduced by 30% to assess crop performance under lower N inputs. Different intercropping combinations were implemented and compared with monocropping systems under both optimal and reduced nitrogen supply. Agronomic parameters, including yield and biomass production, were evaluated together with plant nitrogen status and nitrate accumulation in plant tissues and soil.

The results showed that intercropping systems enhanced nitrogen use efficiency and mitigated the negative effects of a 30% reduction in nitrogen fertilization. In several intercropping combinations, crop yield was maintained or only slightly reduced compared to monocropping under optimal nitrogen supply. In addition, intercropping significantly reduced nitrate accumulation in leaves and soil, indicating improved nitrogen uptake and utilization.

These findings demonstrate that intercropping strategies can effectively reduce nitrogen inputs while maintaining crop productivity in Mediterranean horticultural systems.