Abstract
Fertilizers (nitrogen/N, phosphorous/P, and potassium/K) have been widely applied to increase the productivity of forest plantation, especially in poor soils. This study was to test the effects of fertilization at planting and additional fertilization in the following two years on growth and aboveground biomass (AGB) of a 30-month old plantation of Acacia mangium in Northeast Vietnam. There were four treatments including (1) 1 kg compost/tree at planting and 0.2 kg NPK (16:16:8)/tree/year in the following two years (IC-A-NPK), (2) 1 kg compost/tree at planting and 0.2 kg P (16.5% P2O5) + 0.1 kg K (60% K2O)/tree/year in the following two years (IC-A-PK), (3) 1 kg compost + 0.2 kg NPK/tree at planting and 0.2 kg NPK/tree/year in the following two years (IM-A-NPK), and (4) 1 kg compost + 0.2 kg NPK/tree at planting and 0.6 kg P + 0.1 kg K/tree/year in the following two years (IM-A-PK). The results indicated there was no significant effect of fertilization at planting and additional fertilization on diameter at breast height (DBH), basal area, and AGB between IC-A-NPK (DBH of 8.9 cm, basal area of 7.4 m2 ha-1, and AGB of 37.8 Mg ha-1) and IM-A-NPK (DBH of 10.1 cm, basal area of 9.2 m2 ha-1, and AGB of 47.5 Mg ha-1). Meanwhile, DBH (9.6 cm), basal area (8.6 m2 ha-1) and AGB (44.2 Mg ha-1) in IM-A-PK were significantly higher than that in IC-A-PK (DBH of 8.4 cm, basal area of 6.4 m2 ha-1, and AGB of 31.6 Mg h-1). It was concluded that fertilization at planting of both compost and NPK is not required for A. mangium plantation. While additional fertilization of phosphorus should be applied for higher productivity.
Highlights
The total area of forest plantations in the world was 54.3 million ha and it may reach 90 million ha by 2050 [1]
The objective of this study is to examine the effect of fertilization on Acacia mangium plantations in Northeast Vietnam
In IC-A-NPK and IM-A-NPK treatments (Table 1), there was only a difference in types and amount of fertilizer applied at planting
Summary
The total area of forest plantations in the world was 54.3 million ha and it may reach 90 million ha by 2050 [1]. Because of soil erosion from rain and wind, and nutrition loss from harvesting planted trees, soil quality has decreased, leading to decreased productivity of plantations in the following rotations [2]. Fertilization has been applied for many species to increase their productivity around the world [3,4,5] and is known as a viable silvicultural option [6]. Fertilizers could be applied at and/or after planting annually [9] to support tree growth [10]. The main purpose of fertilization to any forest plantation is to supply nutrients to planted trees for improved growth [11] and higher survival rate [12]. The expectation of growers is that planted trees can absorb as much applied fertilizer as possible [13]
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