# Effect of reduced phosphorus fertilizer application on the physical properties and chemical composition of 15 roasted tobacco leaves

## TL;DR

This study examines how reducing phosphorus fertilizer affects the quality of roasted tobacco leaves in high-phosphorus soils.

## Contribution

The study identifies optimal phosphorus reduction levels for different tobacco leaf positions in phosphorus-rich soils.

## Key findings

- Reducing phosphorus by 25% improved multiple quality indicators of tobacco leaves.
- Excessive phosphorus application negatively affects leaf thickness and chemical composition.
- Optimal phosphorus levels vary depending on the position of the tobacco leaf.

## Abstract

Phosphorus, as a crucial element affecting the physical properties and chemical quality of tobacco leaves, is often used excessively in tobacco production, leading to a prolonged surplus in the soil that poses risks to both the environment and tobacco quality. Despite its importance, there is limited research on the variations in phosphorus levels among tobacco leaves positioned differently in high-phosphorus soils. Therefore, investigating the rational reduction of phosphorus fertilizers in phosphorus-rich soils is essential. This study was conducted in the Guiyang Tobacco Growing Area of Chenzhou, Hunan Province, China. The widely planted Yunyan 87 tobacco variety was utilized and three phosphorus levels were created, including CK representing farmers’ habitual phosphorus fertilizer treatment (P2O5 139.65 kg ha−1), P1 reducing phosphorus by 25 % with base fertilizer (P2O5 104.85 kg ha−1), and P2 reducing phosphorus by 50 % with base fertilizer (P2O5 69.9 kg ha−1). The effects of phosphorus dosage on the physical properties and chemical quality of tobacco were investigated. In the phosphorus-rich soils, the conventional phosphorus application (CK) was optimal for the 5th, 6th, 7th, and 10th leaves; reducing phosphorus by 25 % with basal fertilizer (P1) was optimal for leaves 7–12; and reducing phosphorus by 50 % with base fertilizer (P2) was optimal for leaves 9–11. The excessive phosphorus application could decrease the coordination between the physical properties and chemical composition of tobacco leaves, particularly affecting the leaf thickness, single-leaf weight, total sugar, and reducing sugar. However, reducing the base and phosphorus fertilizer application by 25 % improved multiple indicators of tobacco leaf quality, aligning better with high-quality tobacco standards in the region.