Primary results of research on scientific basics to apply fertiliser for acacia hybrid plantations in Quang Ninh province
Keywords:
Fertiliser application acacia hybrid, plantation, growth, Quang Ninh provinceAbstract
acacia hybrid is a mainly planted species in Vietnnam; in order to increase the timber productivity of plantation, application of fertiliser is one of the most important technical measures of intensive afforestation. The soils were highly acidic at location (pHKCl ≈ 3.57 - 3.73); humus content was poor to medium (1.10 - 2.53%), total nitrogen content (Nts ) was poor to medium (0.063 - 0.15%), P2O5 content was very poor (≤ 3 mg 100 g - 1 soil) and K2O content was poor to medium (6.6 - 17.4 mg 100 g - 1 soil). A mixture of two clones BV16 and BV32 were planted at the experimental site; after one year of planting, the average survival rate was 96,81%, the average growth of root diameter (Doo), height (Hvn) and canopy diameter (Dt) were 3,39 cm, 2,47 m and 1,68 m, respectively. The total N and P2O5 contents (1.08 - 2.531% N and 2.15 - 6.27 mg P2O5 100 g - 1, respectively), after one year of planting, were significantly higher in leaves compared with soil, indicating that Acacia hybrid has a high demand for N and P2O; however, Acacia hybrid has the ability to fix atmospheric nitrogen. In contrast, despite poor K2O content in the soil, K2O content (0.072 - 0.227 mg 100g - 1 leaf) was much lower in the leaves than in the soil, suggesting that the demand for K2O are not much high. Thus, additional application of P2O5 are neccessary when planting Acacia hybrid. After two years of planting that is after one year of additional application of fertiliser with nine different treatments, the average survival rate was 87,12%; tree growth was significant higher in treatments with additional application of P2O5 and K2O fertiliser compared with treatments only applied 200 g NPK (16:16:8). Particularly, the 400 g P2O5 associated with 100 g K2O fertiliser treatment had amongst the highest diameter
at breast height (8,31 cm), height (8,44 m) and canopy diameter (3,83 m). The results indicated that additional application of P2O5 was totally consistent with the previous studies about the nutrient requirements of Acacia hybrid and the ability to supply nutrient in the soil as well.
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