Autumn fertilizer, as the name suggests, many fruit farmers will understand it as fertilizer in autumn. In fact, it should be understood that the fertilizer needed for citrus in autumn is more accurate, because the fertilizer we apply, whether it is ditching, leaching, drip irrigation, and spreading, takes a while to turn the fertilizer into The nutrient elements absorbed and utilized will eventually become plant nutrients to meet the growth needs of citrus.
Why apply heavy fertilizer in autumn? The first is the high temperature in summer and autumn, abundant rain, and active root system, which is conducive to the absorption of fertilizer. The second is the nutritional needs of citrus growth. Below we will explain the importance of heavy fertilizer application for citrus in autumn from ten aspects.
1. Needs for fall shoots to shoot, grow, turn green and mature
Most citrus uses autumn shoots as the main fruit branches (except for kumquats and pomelos). Therefore, to cultivate high-quality and robust autumn shoots is to prepare fruit-bearing branches for the second year. Without autumn shoots, there will be no fruit in the second year. The branches of the year are formed in this way.
To cultivate enough healthy and high-quality autumn shoots, there must be sufficient nutrients and fertilizers.
Nitrogen fertilizer is necessary to promote buds and autumn shoots. Nitrogen fertilizer is indispensable. Under normal circumstances, medium trees should be applied with balanced nitrogen, phosphorus and potassium fertilizer, while weak trees should slightly increase the amount of nitrogen fertilizer. We require 15-20 days in advance after deciding on the release time. The fertilizer can be sprayed, drenched or buried. If it is buried, it needs to be applied earlier to facilitate the restoration of the root system and absorb fertilizer.
2. Need for fruit enlargement
After the autumn shoots of citrus are mature, the fruit enters the second swelling period. The large-fruited citrus (Wokan, Maogukan) swells by one third before the autumn shoots, and the sugar orange swells by one-half. This expansion determines the citrus of the year. For the size and quality of the fruit, a large amount of potassium is needed for fruit expansion, so 60 to 70% of the annual potassium fertilizer needs to be applied within this time. It is generally recommended to use low nitrogen and high potassium + medium and trace elements.
3. Flower bud differentiation needs
The autumn shoots are mature and the fruit expansion is basically over. By November of each year, citrus enters the physiological differentiation period of flower bud differentiation. It also needs sufficient nutrients to grow flowers, especially organic nutrients, such as phosphorus and boron. These nutrients are also absorbed, transformed, and stored from fertilizers in autumn, and a small amount can be supplemented by spraying to promote flower measures. Therefore, in autumn shoot fertilizer, phosphate fertilizer, boron fertilizer, and zinc fertilizer are indispensable.
Insufficient nutrition during the flower bud differentiation period will lead to more abnormal flowers, more or less flowers without flowers in the second year, which will affect the yield and cause serious big and small results.
4. Sugar accumulation needs
When the fruit is about to mature, whether the fruit is sweet or not depends on the level of sugar. The high sugar content is sweet, the sugar content is low, and the fruit taste is light. Amino acids, phosphorus, molybdenum, and magnesium play a decisive role in increasing sugar. Therefore, the autumn fertilizer also needs to increase the application of organic fertilizer (such as peanut bran) and trace elements such as phosphorus, magnesium and molybdenum. If there is a lack of fertilizer, it will definitely affect the accumulation and transformation of sugar, and the quality of the fruit will naturally decrease.
5. Fruit coloring needs
The external quality of citrus depends on pesticides to prevent pests and diseases, and the internal quality of citrus depends on fertilizers. In addition to using good pesticides to prevent pests and diseases, its color must be good, and its background color must be good. Soil organic matter is related, followed by phosphorus, potassium, calcium, magnesium, and molybdenum. Therefore, autumn shoot fertilizer should be a complete nutrient application and supplement.
6. Early market needs
Early ripening of citrus, early market, is carried out under the premise of its natural maturity, rather than using hormones to achieve. If hormones are used to achieve early maturity, it will affect the quality of the fruit and affect the health of consumers, which is not desirable. Early maturity requires that the autumn shoots be placed normally, the fruit is enlarged, the flower bud differentiation is smooth, the sugar is increased and the color is realized, and then the natural coloring, the result of natural maturity, all these physiological activities of citrus require a sufficient nutrition to meet the realization .段落。
7. Need for protection from cold and frost
In winter, if the temperature is below zero or if the temperature suddenly drops more than 15 degrees in a short period of time, it will cause freezing damage to the citrus. It is only the difference between dominant and recessive. The dominant manifestation is deciduous leaves and fruits. Sex affects flowering and fruit setting and yield in the second year, all at the cost of consuming a lot of nutrients.
To improve the cold and frost resistance of citrus, there must be sufficient nutrients as conditions, and these nutrients also come from the absorption, transformation and storage of autumn fertilizer. Therefore, fertilizing in July, August and September also lays the material foundation for the smooth overwintering of citrus trees. This is especially true of late-maturing varieties and trees that bear fruit for overwintering.
8. Need to restore tree vigor
Practice has proved that nutrient-sufficient citrus trees, regardless of the amount of fruit, will basically return to normal within 5-10 days after the fruit is picked, while the tree with a lack of fertilizer can hardly recover in one or two months after the fruit is picked. , Affecting the production and management of the second year. In the winter when the fruit is picked, the trees are in the dormant period, and the ground fertilization is difficult for the fruit trees to absorb. Of course, spraying foliar fertilizer will have a certain effect.
9. Need for spring shoots
When the spring shoots germinate in early spring, the root system is not very active. If it is a large fertilizer applied in winter, the broken roots are not healed and it is more difficult to absorb fertilizer. Therefore, the spring shoots germinate mainly rely on the tree body nutrition of the previous year to promote spring shoots. The amount of nutrients stored in the tree last year determines the health of the spring shoots.
10. Need for flowering and fruit setting in the following year
As mentioned above, the spring shoots complete most of their nutrient supply through the accumulation of nutrients in the previous year, budding, flowering, and even fruit setting are the same. Relying on the nutrient supply stored in the previous year, when the spring shoots mature and become functional leaves, Young fruits will get the nutritional supply of the year. Therefore, adequate, high-quality, and reasonable autumn fertilizer will also benefit the fruit retention rate in the second year.
Recommendations for autumn fertilizer application
1. It is necessary to achieve the combination of four fertilizers, organic fertilizer, inorganic fertilizer, medium and trace elements, and microbial fertilizer.
2. Taking 50 kg fruit trees as the standard, apply 1 to 1.5 kg of special fertilizer for citrus in autumn, 0.3 to 0.5 kg of potash fertilizer, 0.1 to 0.2 kg of trace element fertilizer, and 5 to 10 kg of organic fertilizer.
3. According to the size of the tree and the amount of fruit hanging, the autumn fertilizer can be applied in advance or later, and it can be applied once or divided into two to three times.
4. The application method, you can choose to bury, spread, water, drench and drip irrigation.