Why should fruit trees apply nitrogen fertilizer? What are the fertilization methods and matters needing attention?

In the cultivation of fruit trees, rational fertilization is a very important link, in which nitrogen fertilizer is essential. So why do fruit trees apply nitrogen fertilizer? What are the fertilization methods and matters needing attention?

First, why should fruit trees apply nitrogen fertilizer?

Among the large amounts of elements and trace elements needed by fruit trees, only nitrogen fertilizer can promote the growth and development of fruit trees, because nitrogen is the main component of plant cell protein. it is also a component of nucleic acid, chlorophyll, vitamins, enzyme and coenzyme systems, hormones, and many important metabolic organic compounds. Therefore, nitrogen can promote the growth of new shoots, increase leaf area and leaf thickness. increasing the content of chlorophyll in leaves and improving photosynthetic efficiency are beneficial to the thickening growth of trunk and the rapid expansion of tree crown, and promote early high yield. Proper application of nitrogen can also promote flower bud formation, increase fruit setting rate, accelerate fruit expansion, increase fruit yield and improve fruit quality.

Therefore, in general, in the vegetative growth of fruit trees, it is necessary to provide sufficient nitrogen to fruit trees to meet the vegetative growth needs of fruit trees.

Second, what are the methods and points for attention of applying nitrogen fertilizer to fruit trees?

1. Application method of nitrogen fertilizer

(1) fertilization time: what is the best time to apply nitrogen fertilizer? In principle, it can be at any time during the growing season when you find a nitrogen deficiency. However, in order to achieve the best fertilizer effect, it is often necessary to consider how the nitrogen demand of fruit trees varies with the season, that is, the development of crown and fruit growth in the early growing season requires a large amount of nitrogen, and when the fruit quality is formed in the late growing season, only the most basic nitrogen supply is needed. We believe that there are two time periods for soil nitrogen application: the first is the rapid growth from bud to shoot, and the second is the late growing season, when soil nitrogen fertilizer no longer affects fruit quality (before or just after fruit harvest).

(2) Fertilizer amount: how much nitrogen fertilizer should be applied? The answer to this question depends on three factors: the demand for nitrogen in fruit trees; the natural supply of nitrogen in the soil; and the efficiency of fruit trees in the use of nitrogen fertilizer.

(3) foliar nitrogen application: in addition to soil nitrogen application, foliar nitrogen spraying can also help to meet the nitrogen demand of fruit trees in the early growing season or improve the nitrogen storage of fruit trees after autumn harvest.

If the leaf test in the first year shows that the nitrogen content is less than 2.2%, the application of foliar fertilizer at the early stage of the growing season contributes to fruit setting and early fruit growth. Foliar nitrogen fertilizer can prolong the time of effective pollination and promote cell division, but a lower concentration should be selected to prevent burns of young leaves in the early stage of growth. In general, 0.3% to 0.4% urea solution before flowering can be increased to 0.6% to 0.7% after flowering.

Foliar nitrogen spraying in the late growing season can increase the nitrogen storage level of the tree, thus improving the growth status of the plant in the second year.

2. matters needing attention in the application of nitrogen fertilizer

The main results are as follows: (1) too much nitrogen or lack of nitrogen should not be too much nitrogen in fruit trees, which will cause the loss of balance between carbohydrates and nitrogen or imbalance with other elements, resulting in excessive vegetative growth, excessive growth of branches and leaves, poor differentiation of flower buds and serious drop of flowers and fruits.

(2) the lack of nitrogen nutrition in fruit trees affects the photosynthesis and protein formation of fruit trees. the growth of spring shoots is slow, the growth of branches is weak, and the leaves are thin, small and light, which will cause aging and yellowing of old leaves at the base of branches and early defoliation in autumn, resulting in a large number of fruit drops. When nitrogen is deficient, the flower is small, the fruit setting rate is low, and the fruit is light and poor in quality. Long-term nitrogen deficiency will reduce the stress resistance and short life span of fruit trees.

(3) all kinds of nutrients should be balanced and coordinated fertilization for fruit trees, and attention should be paid to maintaining the balance and coordination of various nutrients. Various nutrients promote and restrict each other, such as phosphorus deficiency will affect the metabolism of nitrogen-containing substances; potassium and nitrogen absorption and protein synthesis have a certain relationship, the application of nitrogen fertilizer, with phosphorus and potassium fertilizer at the same time, the effect of fertilization is good.