Ash habits and fertilization

Ash Tree Cultivation and Fertilization Practices

The ash tree, commonly known as *Fraxinus* or Oleaceae, is a genus that includes around 70 species. These trees are primarily found in the temperate regions of the northern hemisphere, with only a few extending into tropical areas. In China, there are approximately 20 native species, distributed across most provinces. The *Fraxinus* species are mainly found in the Xiaoxing'an Mountains and Wanda Mountains in the northeast, stretching southward to the Changbai and Yanshan Mountains in Hebei Province. They typically grow in valleys and slopes below 700 meters in elevation. Their range extends from northern parts of the northeast down to Guangdong, Guangxi, and Yunnan, east to Jiangsu, Zhejiang, and Fujian, and west to Sichuan and Guizhou. Some species can even be found at elevations up to 3,100 meters in western Sichuan. In Taiwan, the white wax tree (*Fraxinus chinensis*) is widely distributed in river valleys between 800 and 2,000 meters. In Xinjiang's Ili River Valley, which is located at an elevation of 400–700 meters, the *Fraxinus* species are also present. The white wax tree in the mixed forests of Yunnan’s Yanshan Mountain is a light-demanding plant, sensitive to frost. Some young plants are more shade-tolerant, such as the common ash, which thrives in warm and humid climates. Others, like the *Fraxinus sogdiana*, can survive extreme cold down to -40°C. Ash trees prefer deep, moist, and fertile soils, and they are not drought-tolerant or suitable for thin soils. Most species are resistant to saline-alkaline soils. Propagation methods include seeds, cuttings, and stem burying, with techniques varying based on local conditions and economic goals. For sprout production, cuttings are often used in dwarf forests. For timber, seedlings or cuttings are planted and managed accordingly. When cultivating for insect wax production, cuttings are the preferred method. Common diseases include sooty mold and rust, while pests include tussock moths, white wax tip moths, brown helmet moths, four-pointed hornworms, and small flower moths. Before planting, basal fertilization is essential. Top-dressing during the growing season should be adjusted according to the growth potential of the trees. The amount of fertilizer depends on the tree's age, growing season, fertilizer source, and soil properties. Generally, for trees with a trunk diameter below 15 cm, apply 0.5 kg of compost per 3 cm of diameter. For trees with a diameter over 15 cm, apply 1.0–2.0 kg of compost per 3 cm of diameter. To promote crown expansion and flowering in young and middle-aged trees, increase the fertilizer amount. First, dig a fertilization ring ditch with an outer diameter matching the tree’s canopy width. The depth and width should be 25–30 cm. The type of fertilizer should vary depending on the tree species, growing season, and ornamental purpose. Nitrogen-rich fertilizers are ideal for expanding the crown in early stages, while phosphorus and potassium should be used for fruit-bearing species. Pay attention to applying trace elements and root fertilization, gradually shifting toward compound fertilizers. Long-term green spaces should use wide sources of organic fertilizers, mainly manure. Organic fertilizers should be composted before application. Fertilization should be done on sunny days, and the fertilizer should not come into contact with leaves. Composting organic materials with a starter culture, such as Tribol's, can accelerate decomposition and improve the quality of the compost. After treatment with the golden baby starter, decomposed organic fertilizers serve as the foundation for soil fertility improvement. Since organic fertilizers are a complete nutrient source, they play a significant role in greenhouse vegetable production by providing essential nutrients for crop growth, as well as activating soil nutrients and maintaining long-term agricultural productivity.

Bone Screw

Bone screws, also known as fracture fixation screws, are commonly used in clinical practice to fix orthopedic implants.

Bone screws are usually used to fix internal fractures or dislocations by directly screing into two different bone blocks or fixing an internal implant such as a bone plate to achieve fracture fixation, position the bone and promote its healing. Bone screws are used in a wide range of areas, including the shoulder, elbow, hip, knee, spine, etc. For example, pedicle screw systems are used for spinal fusion, and compression bone screws are commonly used for foot and ankle surgery or fixation of other fractures under pressure. Similar to traditional mechanical screws, the main structures of bone screws also include nail cap, nail body, and nail tip. Screws can be used to fix bone plates or bone fragments. When used for the former, they are called plate screws, and when used for the latter (to prevent the collapse of bone fragments), they are called positional screws. The latter can be inserted into the plate holes, and can be placed on the bone alone (also known as compression screws). Compression screws can be used to increase interfragment pressure.

(1) The screw cap

The screw cap has three main functions: the first is to optimize the force. The protruding cap makes the contact area between the screw and bone larger, increases the load area, optimizes the local force at the screw insertion site, and reduces the risk of bone rupture caused by excessive stress. The second is the positioning effect. The prominent cap makes the bone nail can only be screwed into a certain depth to prevent the whole bone nail from being screwed into the bone completely. The third function is to provide the position of force application by rotating the force groove at the cap to move the bone nail forward and drive it into the bone. Now, the force groove is mostly inner hexagonal, which does not require axial force to maintain the actuator in the center position and is suitable for a wider range of fractures.

(2) Screw the body

The size of the nail body determines the strength and fatigue resistance of the bone nail. The larger the diameter of the nail body, the stronger the strength will be, and the corresponding fatigue resistance will be better. In addition to the diameter of the nail body, the pitch and tooth depth of the screw body thread are also the key parameters of the nail body design. Different thread design has an important effect on the pressure and occlusal performance of the screw.

(3) Screw tip

Tapping is the process of phalangeal nail cutting thread in the bone. According to the shape of the nail tip, the bone nail can be divided into self-tapping nail and non-self-tapping nail. The nail tip of the self-tapping nail is sharper and can be directly screwed into the bone without pre-drilling. Usually, self-tapping screws are used for Cancellous bone, and the bone is compressed when the screw is inserted, so as to increase the bone density of the occlusal part locally and enhance the occlusal effect. However, when inserting screws in Cortical bone, the screw channel is generally pre-punched, and then the bone screw is screwed. Usually, the self-tapping screw is not directly used to prevent the bone screw from being stuck or damaged because the cortical bone is too hard.

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