Poplar Fertilizing Time and Methods: Can It Be Spread on the Surface?

AbstractIn the first year after planting, apply the 1st fertilizer from late May to early June, applying 0.05-0.1 kg of urea per tree, which can be broadcast within a 1-2 sq m area around the base of the poplar before rain, then apply fertilizer once more at the end of July, with the same amount and method as the 1st application. In early to mid-May of the second year, apply 0.5 kg of superphosphate and 0.2 kg of urea per tree; it must not be applied on the surface. Instead, open a ring-shaped trench 20 cm deep near the outer edge of the crown projection and apply it in.

I. Poplar Fertilizing Time

1. Fertilizing poplars in the early years can increase the base of growth and also help promote growth in subsequent years. In the 1st year after planting, apply the 1st fertilizer from late May to early June, applying 0.05-0.1 kg of urea per tree, which can be broadcast within a 1-2 sq m area around the base of the poplar before rain; the 2nd fertilizing can be carried out at the end of July, with the same amount and method as the first.

2. In early to mid-May of the 2nd year, apply 0.5 kg of superphosphate and 0.2 kg of urea per tree; in early May of the 3rd year, apply 0.25 kg of urea per tree. During this period, open a ring-shaped trench 20 cm deep near the outer edge of the crown projection, or dig holes 20 cm deep at no fewer than 3-4 places along the outer edge of the crown, then apply the fertilizer in and cover with soil immediately, ensuring the holes are evenly distributed in all directions.

II. Poplar Fertilizing Methods

1. When planting, applying base fertilizer in the planting hole has a relatively good effect, as it can supply fertilizer over the long term and improve the soil's physical and chemical properties. The base fertilizer is generally farmyard manure and slow-release chemical fertilizer; during this period, soil-and-miscellaneous manure, cake fertilizer and green manure for green manuring can be used.

2. Soil-and-miscellaneous manure can be applied at 10-20 kg per tree, rapeseed cake or cottonseed cake at 2-5 kg per tree, applied after crushing, and green manure for green manuring at 10 kg per tree. Generally, no topdressing is needed in the year of planting, because the seedling root system is in a recovery period and its ability to absorb nutrients is relatively weak.

3. For each young tree, apply 150 g of nitrogen, 150 g of phosphorus pentoxide, 25 g of potassium oxide, and 10 kg of false indigo green manure. Generally, the height growth of young poplar stands can reach 2-3 m. In the Luxi area, planting false indigo and sand sainfoin under the forest as green manure and turning them in promptly has very good economic and ecological benefits.

4. Poplar fertilizing is generally mainly nitrogen fertilizer. For soil with low organic matter content, farmyard manure can be used as base fertilizer, and then nitrogen fertilizer and phosphate fertilizer can be applied as topdressing, which can significantly promote poplar growth. During this period, combined application of nitrogen and phosphorus, or nitrogen, phosphorus and potassium, has better effects than applying any single one. Therefore, it is best to apply two or three fertilizers in combination, mainly nitrogen fertilizer, with the amount determined according to soil conditions.

5. The amount of nitrogen is generally 250-500 g per tree, with nitrogen : phosphorus pentoxide : potassium oxide = 3 (2) : 1 : 0.5. The urea generally used contains 46% nitrogen, and superphosphate contains 14% P2O5.

6. During this period, applying nitrogen fertilizer, phosphate fertilizer and green manure has a very obvious promoting effect on poplar growth. The volume growth in the fertilized area can be increased by 274.2% compared with the control area, DBH by 74.5% compared with the control, and tree height by 69% compared with the control. The effect of green manure is relatively obvious, followed by phosphate fertilizer and nitrogen fertilizer, while the effect of potassium fertilizer is poor. Chemical fertilizer should be used in combination with green manure.