In plain agricultural areas, comprehensive land preparation is not necessary to develop poplars. Dig a pit before planting trees. Specification of holes: to cultivate large-diameter timber, large holes should be dug,100×100×100 cm. To cultivate small-diameter timber, the pulp can be smaller, but it should not be less than 60×60×60 cm.
Second, choose improved varieties and strong seedlings.
Select improved varieties. According to the local climate, site conditions and different cultivation objectives, select suitable and excellent varieties that have passed the examination and approval of provincial forest varieties.
Choose strong seedlings. Select 1 or 2-year-old seedlings with a height of 4.5 meters and a ground diameter of more than 3.5 cm, complete roots and Miao Zhuang, high lignification degree, full terminal buds, no mechanical damage and no diseases and insect pests.
Third, planting
1, seedling treatment: in all aspects of seedling raising, seedling transportation and planting, water loss of seedlings should be prevented. In the seedling field, we should follow the principle of watering before seedling, pay attention to protect the root system in the shipment of seedlings, make the root system complete, fresh and moist, and try to grow, transport and plant with it. For the seedlings that can't be planted in time, some clones of Populus deltoides should be soaked in clear water for 1-2 days before planting. Long roots should be cut off before afforestation, and the length of lateral roots should generally be kept at 30 cm (too long, it is easy to appear nest roots 1 when planting. For some seedlings whose terminal bud or even the top is damaged during seedling transportation, the terminal bud should be cut off when cutting roots, and then cut back to the position above the first strong bud at the top 1 cm.
2. Planting: The planting time is in spring, late autumn and early winter (from the end of 10 to the middle of 1 10), which is suitable for winter poplar afforestation after defoliation, before soil freezing and before spring germination. Planting depth: According to the soil conditions, it is appropriate to plant about 60 cm in dry and loose soil, which can increase the rooting of seedlings and improve the drought and wind resistance, but it is not suitable for deep planting in clay and low-lying land. Planting method: during afforestation, it is required to plant in big holes, straighten, plant straight, fill the soil in layers, and step on it in layers, so that the roots of seedlings can stretch and closely connect with the soil, water them immediately after planting, straighten the seedlings after seepage, and fill the holes with soil.
Five, shaping and pruning
Plastic pruning should be carried out in autumn and winter and early spring when trees stop growing. Young trees are pruned. If the seedlings are planted with big seedlings, they will not be pruned within 3 years. Three years later, when the diameter at the height of 6 meters is greater than 10cm, 1 time pruning will be carried out, and the trunk without side branches will be raised by 3 ~ 4 m to cultivate high-knotless and high-quality timber. But the trimming should not be excessive. It should be emphasized that plastic surgery should start after the growth of 1 year or in the spring of the following year, and a straight trunk with a height of 10- 14m will be formed within 3-5 years. The method of shaping is to cut off the competitive side branches that affect the growth of the top main tip. With the height of the tree, it is necessary to cut off the coarse competitive branches in the middle and lower part of the crown to below 8m. When the diameter of the upper branches on the trunk below 8 m reaches 10cm, the side branches should be trimmed from bottom to top to 8 m in order to ensure that there is no knot scar outside the trunk of 10cm. Pruning height 1-3 years, a little pruning, 4 ~ 5 years to 1/3 height, 6 years to 1/2 ~ 2/3 height. The sprouting strips on the trunk should be removed in time.
Six, planting poplar fertilization requirements
If the soil organic matter content of poplar plantation is low, a large amount of organic fertilizer and 100kg ~ 200kg stable manure should be applied to build a high-yield Yang Shulin in this kind of soil. Stir the raw soil at the bottom of the planting hole evenly, and then cover the topsoil from 10 cm to 15 cm for afforestation, so that the seedlings will not contact the fertilizer. When retting organic fertilizer, adding calcium superphosphate is better. At the same time of afforestation, 0.5 kg to 0.7 kg of calcium superphosphate can be mixed into each hole, but special attention should be paid not to let the phosphate fertilizer contact with the root system of seedlings, because most of the calcium superphosphate produced by small fertilizer plants contains free sulfuric acid residue, which will cause burns if it contacts the root system.
Seven, do a good job in tending management
As the saying goes: "Three points for work, seven in charge." If trees are not well managed, the benefits will not be high. For example, in the fast-growing and high-yield poplar forests developed in our city a few years ago, there were some problems such as weak seedlings, unscientific planting and inadequate management, which caused many poplar high-yield forests to fail to meet their due high-yield indicators. The main links of poplar high-yield forest management are:
1, topdressing and watering.
Twice a year, the first time in early April, the fast-growing period of spring wood, 25 to 30 kilograms of urea per mu. For the second time, in the fast-growing period of autumn timber in late July, 20 ~ 25 kilograms of compound nitrogen and phosphorus fertilizer was applied per mu, and water was poured once in time after fertilization.
2, pest control
The main pests and diseases that harm poplars in our city are canker, black spot, stinkbug of membrane shoulder net, inchworm and moth. In recent years, the spread of disasters has accelerated, and disasters have broken out in some places. Seriously affect the growth of trees. We must attach great importance to it, take active measures, adhere to the principle of "prevention first, comprehensive prevention", and achieve early treatment, minor treatment, cure and harmlessness to ensure the healthy growth of trees.
prune
Pruning and tending of poplars aim at high yield and high quality. The pruning of young forests in Yang Shulin should adopt the methods of light pruning, heavy crown protection, branch contention and auxiliary branch maintenance. In general, poplar 1-3 years should not be overhauled, so as not to weaken the tree potential and inhibit the growth of poplar. When the DBH of poplar grows to 10 cm, trim the lateral branches, keep the crown 2/3-3/4 of the trunk height, and only trim the special branches and neck branches from the upper part. Trim the big branches twice to prevent the wound from being too big. For annual and biennial competitive branches and overgrown branches, they can be pruned properly in the growing season, and 1/4- 1/3 is generally pruned to weaken their growth potential and prevent them from developing into thick branches, so as to cultivate perfect dry shapes. In the future, it can be trimmed appropriately according to the growth of the crown. Generally, the pruning can be stopped when the last branch is 8- 10 meters above the ground, and better knotless wood can be obtained. Excessive pruning will weaken the tree and inhibit its growth.
(Author: Heilongjiang founder county Forestry Bureau 150800 Forest Protection Station)