Objective The aim was to investigate the fate of nitrogen (N) from sugarcane leaves under furrow application in the subsequent two sugarcane seasons, in order to provide a basis for the efficient utilization of sugarcane leaf incorporation into the soil.

Method Using the sugarcane variety Guitang 44 as the experimental material, the N utilization and fate of ¹⁵N-labeled sugarcane leaves were analyzed with four treatments in the field: 100% leaves applied at the bottom of furrows (R1), 100% leaves applied on the surface of furrows (R2), 50% leaves applied at the bottom of furrows + 50% leaves applied on the surface of furrows (R3), and 100% leaves mixed with furrow soil (R4).

Result Across the four treatments, 5.00% - 6.48% and 5.55% - 6.25% of N from sugarcane leaves were absorbed by newly planted sugarcane and first-ratoon sugarcane, respectively. The N from sugarcane leaves contributed 3.10% - 3.33% and 2.02% - 2.20% to the N requirements of newly planted sugarcane and first-ratoon sugarcane, respectively. The utilization rate of N from sugarcane leaves in R4 was cumulatively 0.25 - 1.97 percentage points higher than that in the other treatments. After two crops, the N from sugarcane leaves was retained in the soil layer above 40 cm for all treatments, with a residual rate of 55.00% - 61.65%, where R1 had higher residues and R4 had lower residues. The loss rate of N from sugarcane leaves was 27.80% - 32.48%, with R4 having higher losses and R1 having lower losses. In two crops, the cumulative dry matter accumulation in sugarcane stalks was the highest in R4, increasing by 5.48% - 20.36% compared with the other treatments.

Conclusion The absorption and utilization rate of N from incorporated sugarcane leaves was very low, with a large amount of residue remaining, and its contribution to the N requirements of sugarcane was limited.