According to the biological characteristics of garden trees and the requirements and conditions of cultivation, the characteristics of fertilization are as follows: 1. Garden trees are perennial plants that grow in the same place for a long time. From the point of view of fertilizer types, organic fertilizer should be given priority to and chemical fertilizer should be applied appropriately. Fertilization method is mainly based on base fertilizer, and both base fertilizer and topdressing should be applied. Secondly, there are many kinds of garden trees with different functions, and their ornamental, protective or economic effects are different. Therefore, it is reflected in the differences of fertilization types, dosage and methods. There are many experiences in this field, which need to be systematically analyzed and summarized. From the last article, we can see that the environmental conditions of garden trees are very different, including barren hills, wasteland, fertile plains, near water and low wetlands around buildings, which increases the difficulty of fertilization. Different fertilization methods should be adopted according to the characteristics of cultivation environment. At the same time, when fertilizing the trees in the garden, we must pay attention to the beauty of the garden to avoid the smell that hinders the activities of tourists, and cover the soil immediately after fertilization.

1. Grasp the characteristics of fertilizer demand of trees in different phenological periods.

Trees need different nutrients at different phenological stages. Under the condition of sufficient water, the growth of new shoots depends largely on the supply of nitrogen, and the nitrogen requirement increases gradually from the early growth stage to the peak growth stage. With the end of shoot growth, although the demand of plants for nitrogen has been greatly reduced, the synthesis of protein is still going on. The thickening of the trunk continued until autumn. In addition, plants quickly accumulate protein and other nutrients, which play an important role in the growth and flowering of new buds in the following spring. Therefore, trees need nitrogen fertilizer throughout the growth period, but

The demand is different.

In the slow growth period of new shoots, besides nitrogen and phosphorus, a certain amount of potassium fertilizer is needed. During this period, the vegetative organs of trees not only grow weakly, but also accumulate nutrients in plants. The aging speed of leaves is accelerated. In order to keep the photosynthetic capacity of these old leaves high, stop the growth of plants in time and improve the cold resistance, it is necessary to supplement potassium fertilizer besides nitrogen and phosphorus during this period. Under the condition of ensuring the supply of nitrogen and potassium, applying more phosphorus fertilizer can promote the buds to pass through each growth stage quickly, which is beneficial to differentiate into flower buds.

During flowering, fruit setting and fruit development, plants are in urgent need of various nutrients, and the role of potassium fertilizer is more important. In the fruiting year, potassium fertilizer can enhance plant growth and promote flower bud differentiation.

Trees need more fertilizer in spring and early summer, but during this period, due to the weak activity of soil microorganisms, the nutrients available for absorption in the soil are just in a period of less. It is one of the tasks of soil management and fertilization to solve the contradiction between the high demand for nutrients by trees and the low content of available nutrients in soil during this period.

At the later stage of tree growth, the demand for nitrogen and water is generally small, but at this time, the nitrogen and soil water absorbed by the soil are high, so irrigation and fertilization should be controlled at this time.

According to the observation of apple, jujube, peach and other trees marked by p32 in Hebei Agricultural University, nutrients first meet the most vigorous organs, that is, nutrients have their distribution centers, and with the progress of phenology, the distribution centers are also shifting. For example, in' Jinguan' apple, the p32 content is more in the flower bud, the most in the flower at flowering stage, the most in the fruit at fruit setting stage, and the most in the flower bud at flower bud differentiation stage. The research of Shaanxi Fruit Research Institute shows that if the amount of topdressing exceeds the general production level, the fruit setting rate can be improved by taking flowering and fruit setting as the nutrient distribution center. If you miss this period, even a small amount of fertilization can promote nutritional growth, often

Aggravate physiological fruit drop.

The fertilizer demand period of trees varies with tree species, for example, citrus can absorb nitrogen almost all year round, but the absorption peak is in the middle summer when the temperature is higher; Phosphorus is mainly absorbed in the high temperature season when branches and roots grow vigorously, and it is obviously reduced in winter; Potassium absorption is mainly in May-165438+1October. However, chestnut began to absorb nitrogen from germination, and after the new shoots stopped growing, the fruit absorbed the most at the hypertrophy stage. The absorption of phosphorus is relatively stable from flowering to late September, and almost stops after 1 1 month. Potassium was rarely absorbed before flowering, and increased rapidly after flowering (June), reaching the absorption peak at the fruit hypertrophy stage and dropping sharply after 10. It can be seen that the application period of the three elements also varies with tree species. It is very important for controlling the growth and development of trees and formulating effective fertilization methods to understand the requirements of trees for various nutrients in different phenological periods.

2. Master the relationship between fertilizer absorption by trees and the external environment.

The absorption of fertilizer by trees not only determines the biological characteristics of arid plants, but also is influenced by external environmental conditions (light, heat, gas, water, soil reaction and soil solution concentration). Adequate light, suitable temperature and strong photosynthesis will increase the amount of fertilizer absorbed by roots; If photosynthesis is weakened, the synthetic substances transported from leaves to roots are reduced, and the speed of trees absorbing nutrients from soil is also slow. When the soil is poorly ventilated or the temperature is not suitable, a similar phenomenon will occur.

Soil water content is closely related to fertilizer efficiency. Soil moisture deficiency, fertilization is harmful. Because the concentration of fertilizer is too high, trees can't absorb and use it, and they are poisoned. In areas with stagnant water or rainy weather, fertilizer is easy to leach out, which reduces the utilization rate of fertilizer. Therefore, fertilization should be based on the local soil moisture change law or combined with irrigation.

The pH value of soil has a great influence on the absorption of fertilizer by plants. Under acidic reaction conditions, it is beneficial to the absorption of anions; Under alkaline reaction conditions, it is beneficial to the absorption of cations. Under acidic reaction conditions, it is beneficial to the absorption of nitrate nitrogen; but

Neutral or slightly alkaline reaction is beneficial to the absorption of ammonium nitrogen, that is, when pH =7, it is beneficial to the absorption of NH4-; When pH = 5 ~ 6, it is beneficial to the absorption of NO3.

The acid-base reaction of soil not only directly affects the absorption of fertilizer, but also affects the solubility of some substances (for example, improving the solubility of calcium phosphate and magnesium phosphate under acidic conditions). Under alkaline conditions, the solubility of iron, boron, aluminum and other compounds decreases), which indirectly affects the absorption of nutrients by plants.

3. Master the nature of fertilizer

Different fertilizers have different fertilization periods. Fertilizers, such as ammonium bicarbonate and calcium superphosphate, which are easy to be lost and volatilized quickly or easily fixed by soil after application, should be applied before trees need fertilizer. Slow-acting fertilizers, such as organic fertilizers, should be applied in advance because they need to be decomposed and mineralized before they can be absorbed and utilized by trees. The same fertilizer has different effects due to different application periods. For example, according to the report of Horticulture Department of Beijing Agricultural University, applying the same amount of ammonium sulfate in autumn has higher flowering rate, greater growth of trunk diameter and higher nitrogen content of 1 annual branches than applying it in spring. Therefore, fertilizer should be applied in the period with the highest economic benefit. According to the report of Shandong Laiyang Agricultural School (1972), apples are bright and colorful, and there is a lot of wax in the early stage of topdressing. The later the fertilization period, the greater the fruit color difference and the less waxy the pericarp, which is contrary to the above results. Because the application of nitrogen fertilizer is late, it promotes the growth of nutrients and prevents the accumulation of nutrients. There are different and contradictory literature reports about when the nitrogen fertilizer application period is appropriate. Therefore, when determining the application period of nitrogen fertilizer, we should comprehensively consider the nutritional status of trees, fertilizer absorption characteristics, soil fertilizer supply and climate conditions in order to achieve better results.