1, increase the application of organic fertilizer. In late autumn and early winter, ditches are dug within 50 ~ 100 cm from the base of poplar trunk, generally 20 ~ 30 cm wide, 20 ~ 30 cm deep and 100 cm long. After ditching, fill the ditch with farm manure, determine the amount of fertilizer according to the age of the tree, and then cover the soil. The ditch can be opened in the opposite direction.

2, pruning. Poplar pruning should give consideration to both high quality and high yield. Young forests should be lightly cut, crown protected, branches contested and branches kept. Poplar should not be overhauled, so as not to weaken the tree potential and inhibit growth.

Generally, a small number of 1 ~ 3-year-old poplars are pruned to keep the trunk straight, 4-5-year-old poplars are pruned to 1/3 tree height, and after 6 years, they are pruned to 1/2 tree height. When the last branch is 6 ~ 8 meters above the ground, pruning can be stopped and good wood without knots can be obtained.

Extended data;

Poplar is the most widely distributed and adaptable tree species in the world. Mainly distributed in temperate and cold temperate forest trees in the northern hemisphere, latitude 22-70, altitude as low as 4800 meters. In China, the distribution range spans 25 ~ 53 N and 76 ~ 134 E, covering northeast, northwest, north and southwest.

Poplar natural forest covers an area of more than 20 million hectares (poplar is the dominant tree species in the world), and there are about 100 natural tree species. The countries with the widest distribution of natural poplar varieties are Russian, China, Canadian, American, Italian, French and other countries.

Populus tomentosa is widely distributed in Liaoning (South), Hebei, Shandong, Shanxi, Shaanxi, Gansu, Henan, Anhui, Jiangsu, Zhejiang and other provinces, with the middle and lower reaches of the Yellow River as the center.

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