What Fertilizer Is Best for Poplar Trees? A Detailed Guide to Scientific Fertilization Methods
For poplar trees, a compound fertilizer leaning toward nitrogen is best. Usually in June-July, 15-20 kg of urea and 25-30 kg of compound fertilizer can be applied per mu, with a fertilization depth of 5-10 cm. After fertilizing, cover with soil and water thoroughly. The fertilizer can also be diluted and sprayed onto the seedbed, then the seedlings rinsed with clean water. Topdressing can be carried out when the seedlings are growing lateral roots. Do not fertilize after the Start of Autumn, to prevent excessive vegetative growth of the seedlings.
Fertilization methods:
When planting a forest, applying base fertilizer in the planting holes has a very good effect, as it can supply nutrients over a longer period and improve the physical and chemical properties of the soil. Base fertilizer is generally farmyard manure and slow-release chemical fertilizer; soil-and-miscellaneous manure, cake fertilizer, and green manure for turning under can be used. Soil-and-miscellaneous manure can be applied at 10-20 kg per plant, and cottonseed cake or rapeseed cake at 2-5 kg per plant, applied after being crushed; green manure turned under, 10 kg per plant. In the year of planting, there is no need for topdressing, because the seedling root system is still in the recovery stage and its ability to absorb nutrients is relatively weak.
For each young tree: 150 g of nitrogen, 150 g of phosphorus pentoxide, 25 g of potassium oxide, and 10 kg of false indigo green manure. Under this fertilization level, the DBH growth of I-214 poplar young forests over two years can reach about 5 cm, and the height growth 2-3 m. In the Luxi area, planting false indigo and erect milkvetch under the forest as green manure and turning them under in time has good economic and ecological benefits.
Poplar fertilization should be based mainly on nitrogen fertilizer. In soil with low organic matter content, using farmyard manure as base fertilizer and then topdressing with nitrogen fertilizer and phosphorus fertilizer can clearly promote poplar growth. Combined application of nitrogen and phosphorus, or of nitrogen, phosphorus and potassium, is more effective than applying any one alone. Therefore, it is best to apply two or three fertilizers in combination, with nitrogen fertilizer as the main component. The amount to use and the ratio of nitrogen, phosphorus and potassium are determined according to soil conditions. The amount of nitrogen is generally 250-500 g per plant, with nitrogen : phosphorus pentoxide : potassium oxide = 3(2) : 1 : 0.5. At present, poplar fertilization in many places applies only nitrogen fertilizer, and the tendency to neglect phosphorus fertilizer should be corrected. The author proposes the following fertilization plans for cultivating large-diameter and small-diameter timber, for reference. The urea used contains 46% nitrogen, and the superphosphate contains 14% P2O5.
Applying nitrogen fertilizer, phosphorus fertilizer and green manure clearly promotes poplar growth. In fertilized plots, the volume growth can be increased by up to 274.2% compared with the control plot, the DBH by 74.5% compared with the control, and the tree height by 69% compared with the control. The effect of green manure is the most obvious, followed by phosphorus fertilizer and nitrogen fertilizer; the effect of potassium fertilizer is not significant. Chemical fertilizers should preferably be used in combination with green manure.