Effect of mineral fertilizer addition on Pinus massoniana Lamb leaf litter decomposition and on amino acid concentration in a subtropical forest

Leaf litter constitutes a major fraction in litter production in Masson pine forests. However, productivity declines due to infertile soil. In these plantations, fertilization is a key management practice to sustain productivity. Our study aimed to: (1) evaluate the effect of mineral fertilizer on the decomposition dynamic of leaf litter; (2) evaluate its effect on amino acid concentration; and (3) explore the relationship between soil properties and amino acid.

Leaf litters of Masson pine were placed into litter bags in the following treatments: Control (CK), N fertilization (+ N), N and P fertilization (+ NP), and N, P, K fertilization (+ NPK) and collected every three months during 12 months of decomposition. Litterbags and chromatography techniques were employed to assess litter mass and amino acid concentration.

Our study found that Masson pine leaf litter significantly affected by fertilizers, and the decomposition process accelerated with + NPK, and + NP. Out of the 16 amino acids, only GAALAGL showed significant increase under fertilizer treatments. The total amino acid concentrations were 229.33 ± 4.46, 205.37 ± 4.49, 206.28 ± 4.17, 186.74 ± 4.32 mg/g, respectively, in + NPK, + NP, + N, and CK. Soil chemical properties had a negative effect on amino acid concentration except for GVITMAS. N and P concentrations in leaf litter significantly increased while K concentration decreased; similarly, soil N and P exhibited significant increases, while K decreased.

NPK fertilizer might be the preferred management option as it can positively impact leaf litter decomposition and increase amino acid concentration. The findings serve as a valuable reference for implementing fertilization strategies in subtropical forests.