Soil aeration improves tomato fruit yield by regulating root characteristics and soil nitrogen cycle

Soil aeration plays a critical role in regulating root development and soil nutrient dynamics, which are essential for optimizing tomato fruit yield. However, the mechanisms underpinning how different soil aeration techniques influence root characteristics and soil nitrogen cycling remain underexplored. This study aims to evaluate the effects of micro-nano bubble aeration and underground air layer treatments on soil oxygen concentration, root morphology, nitrogen cycling, and ultimately tomato fruit yield. A two-season field experiment was conducted in Xi'an, China. Micro-nano bubble aeration treatments were applied before irrigation with dissolved oxygen levels set at 6.5 mg/L (N1) and 8.0 mg/L (N2). Additionally, underground air layer treatments were implemented without vertical pipes (L1) and with vertical pipes (L2). Measurements included soil pore O₂ and CO₂ concentrations, root morphology and activity, root extract concentrations, soil nitrogen forms (NO₃^--N and NH₄⁺-N), and tomato yield. Both aeration treatments significantly increased soil pore O₂ while reducing CO₂ levels, promoting improved root morphology, higher root extract concentrations, and elevated root activity. This led to enhanced tomato yields. Soil aeration also altered nitrogen cycling, increasing nitrate (NO₃^--N) and decreasing ammonium (NH₄⁺-N) concentrations. It is recommended to maintain soil moisture at 60%-90% field capacity for optimal results, with the N2 treatment preferred for short-term cultivation and the underground air layer treatment advised for long-term tomato production. This study provides comprehensive insights into how soil aeration techniques regulate root systems and soil nitrogen dynamics, offering practical recommendations for improving tomato yield through enhanced soil management.