Work

Canopy rainfall partitioning and hydrological nitrogen and phosphorus losses under contrasting fertilization regimes in a flue-cured tobacco field

Year: 2026

Type: article

Abstract: Introduction Fertilization can alter both soil properties and crop canopy characteristics, with potential implications for hydrological nutrient export, yet field evidence on the relationship between canopy rainfall redistribution and nutrient-loss patterns remains limited. Methods During the 2023 tobacco-growing season, we conducted a field experiment in a flue-cured tobacco–faba bean rotation system in the Erhai Lake Basin, China. We compared conventional fertilization (CF), organic substitution (OS, in which chemical-fertilizer N under CF was fully replaced on an equal-N basis with commercial organic fertilizer), and optimized fertilization (OF, with chemical-fertilizer N and P inputs reduced by 25% and K input increased by 25% relative to CF). Soil properties, aggregate stability, tobacco growth and nutrient status, canopy rainfall partitioning during three late-season rainfall events, and seasonal N and P losses through runoff and leaching were quantified. Results Compared with CF, OS reduced soil bulk density by 8.53% and increased soil organic matter, porosity, and moisture content by 9.71%, 11.61%, and 15.35%, respectively, while also improving aggregate stability. OS increased leaf N concentration, maximum leaf area, and yield by 25.44%, 17.25%, and 11.14%, respectively, despite nonsignificant differences in leaf area index and canopy coverage. Fertilization regime significantly affected canopy interception and throughfall, with OS showing the numerically highest interception and lowest throughfall across the three events. OS reduced surface runoff by 7.04%, runoff-mediated TN and TP losses by 22.46% and 20.63%, and leaching-mediated TN and TP losses by 24.70% and 30.61%, respectively. OF showed more moderate soil and plant responses but lowerrunoff-mediated TP and leaching-mediated TN and NH 4 + -N losses. Exploratory analyses indicated numerically stronger associations of canopy interception with runoff-mediated than with leaching-mediated nutrient losses. Discussion Contrasting fertilization regimes were associated with coordinated soil, plant, canopy-hydrological, and nutrient-export responses. Rainfall partitioning differed despite similar LAI and canopy cover, indicating that bulk canopy-size metrics do not fully capture canopy hydrological functioning. The stronger association of canopy interception with runoff-mediated losses suggests a closer relationship between canopy rainfall redistribution and surface nutrient transport, providing a process-oriented basis for evaluating nutrient-loss mitigation.

Source: Frontiers in Plant Science

DOI: 10.3389/fpls.2026.1939056