Abstract

Purpose: Adequate water availability is critical for producing hazelnuts with high nutritional content. However, the availability of water for irrigation is becoming increasingly limited due to increased demand and changing precipitation patterns. Adequate water management is fundamental for simultaneously maximizing production, quality, and soil health. Methods: Here, we studied the effects at the end of three years of irrigation levels (150%, 100%, 75%, and 50% of the water replacement of potential evapotranspiration [ETp]) on soil physicochemical properties (organic matter, aggregate stability, texture, pH, and total elements) and soil biological properties (nematode abundance and soil enzymes), in hazelnut orchards of two localities (Coihueco and Ñiquén) in Chile that differed in their fertility and soil properties. Results: Irrigation consistently changed the soil physiochemistry but did not modify its biological properties. Lower irrigation (50% ETp) reduced the redox potential and increased the pH of the soil compared with higher irrigation doses (100% ETp). Locality was the main driver of physicochemical and biological properties of soil. Coihueco, the site with greater OM and nutrients (P, S, Ca, and Zn), had greater nematode abundance (268%) and enzymatic activity as ?-glucosidase (162%) and N-acetyl-?-glucosaminidase (145%) than Ñiquén. Other effects of irrigation were more evident in Coihueco, where higher irrigation (150% ETp) decreased clay and Ba (56%) and increased the ratio of CP (85%) and NP (206%) compared to lower irrigation (50% ETp). Conclusions: Doses below 150% ETp are adequate for maintaining soil functionality, particularly in high-fertility areas. We recommend irrigating hazelnut trees with 50% ETp to conserve water resources, while simultaneously maintaining soil function. © The Author(s) under exclusive licence to Sociedad Chilena de la Ciencia del Suelo 2025.