EFFECTS OF FERTILISER ON THE EARLY GROWTH OF MIXED NATIVE TIMBER SPECIES PLANTATIONS FOR SAW-LOG PRODUCTION IN PHU THO PROVINCE

Abstract

Although the planting of native tree species has been incorporated into numerous programs and projects, success was limited, partly because of land degradation and insufficient soil nutrients. Fertiliser application is a practice used to improve soil conditions and enhance the growth and productivity of planted forests. The study was conducted to evaluate the impact of additional composted cow manure and varying chemical fertiliser doses on the early development of four native timber species: Cinnamomum balansae H. Lec, Michelia tonkinensis A.Chev, Lithocarpus ducampii A. Camus, and Prunus arborea (Blume) Kalkman, planted in alternating rows within a mixed plantation system in Phu Tho province. The experiment was designed as a completely randomised block with three replicates and four fertiliser regimes. Trees were planted in June 2022, and data were collected until December 2024. The results indicated that: (1) Cinnamomum balansae and Prunus arborea achieved the highest growth performance under a fertilization regime consisting of a basal application of 300g of fused phosphate (16.5% P2O5) and 2kg of composted cow manure per tree, followed by 100g topdressing of NPK 16:16:8 in the first year and 400g of NPK 16:16:8 annually for the next 2 years. Meanwhile, Michelia tonkinensis and Lithocarpus ducampii responded best to a treatment involving a basal dose of 300g of fused phosphate and 1kg of manure per seedling, followed by annual applications of 200g of NPK 16:16:8 for three years. These findings provide useful insights into nutrient management practices for establishing productive mixed-species plantations of native tree species for saw-log production.