Why must longan change the traditional fertilization technology?

Fertilization plays a key role in improving the nutritional level of longan trees, promoting the selection of new shoots and cultivating fruiting mother branches, improving yield and quality, and reducing the fruits in different years. Generally speaking, the fertilization of fruiting trees is far more complicated than that of young trees, and the requirements are stricter, because fertilizer has an impact on vegetative growth, flower bud differentiation and fruit-setting ability. The goal of rational fertilization is to adjust the growth results of longan according to the biological characteristics and ecological environment of longan, as well as the application period and dosage of fertilization. Therefore, fertilization can promote these effects and ultimately help to improve the yield and quality of fruits.

The traditional fertilization method is to apply fertilizer several times in stages, generally 5 ~ 6 times a year (Table 26), as follows:

Table 26 Fertilization amount of adult orchards in main longan producing areas of Fujian Province The annual fertilization amount of fertilizer types in main longan producing areas (kg/ plant) is converted into pure nitrogen, phosphorus and potassium (kg/ plant) 1 ~ 3 bean cake: pig manure: water (3:10:100)/kloc-0 ~. Mix 4 ~ 5 cow dung 00: 100) 15 ~ 252 ~ 3 human excrement 50 ~ 100 n: 1.30 south or ammonium sulfate1~ 2p: 0.60an8 ~/kloc-. Water (2.5:10)150 ~ 250n: 0.42 Jinjiang or ammonium sulfate 1 ~ 1.5p: 0.304 ~ 5 or bean cake compost 5k: 0.3 1 pig manure: water. 00 nN: 1.02 points or bean cake 1.5 ~ 2.5p: 0.403 ~ 4 ammonium sulfate 0.25 ~ 0.5k: 0.38 you 6 ~ 7 bean cake 1.5 ~ 2.58 ~ 10 people shit 50. 438+000 p: 0.97 field 9 ~ 10 human excrement and urine and bean cake 100 1.5 ~ 2 k: 0.792. In February, nitrogen fertilizer was the main fertilizer, combined with phosphorus and potassium application. It can promote ear development, increase heading rate and increase ear number. During this period, attention should be paid to prevent excessive application of nitrogen fertilizer from causing "shoot grabbing" and affecting yield. Timely fertilization and proper thinning of ears during the period from Qingming to Grain Rain in April have significant effects on sprouting summer shoots, increasing fruit ears and improving fruit setting rate. Summer shoots are a good foundation for germination of autumn shoots, and promoting the growth of summer shoots has a certain effect on preventing the fruits of big and small years. In the period of rapid growth of young fruits in late June, the first summer shoot is also enriching and continuing the germination of the second summer shoot. Fertilization at this stage can promote the development of young fruits and the growth of summer shoots. But also contribute to that formation of autumn shoots of good bear mother branches. Judging from the area we investigated, this kind of fertilization is still uncommon. The main reason is that the source of fertilizer is insufficient, but the production areas with fine management and stable output pay more attention to it, which has a certain effect on the output of the current year and the results of the next year. From the end of July to the beginning of August, the pulp expands rapidly and the root system absorbs fertility. Fertilization has obvious effect on increasing yield and reducing fruit drop in the later stage. Moreover, summer photography is still relatively rich. In order to alleviate the nutrient contradiction between fruit growth and summer shoot development, this topdressing also has considerable effect. Longan bears fruit in different years in many areas, which is related to the lack of strong fruit fertilizer. We should pay attention to it as much as possible in the future. From September to 65438+10, slow-acting and quick-acting mixed fertilizers can be applied to restore tree vigor, which has great influence on longan yield in the following year.

Fertilization method: when applying slow-release organic fertilizers such as decomposed manure, manure, compost and cake fertilizer. Shallow ditches should generally be dug at drip line on the edge of the crown. Annular ditch can be used when young trees are young, and long ditch or half-moon ditch can also be used when the crown is large. Generally, the ditch depth is 15 ~ 20 cm, and the size of the ditch depends on the amount of fertilizer applied. For example, the long ditch is about 30 wide. Fertilizer should be applied through water or rain, and cover the soil after it penetrates into the soil. After fertilization in autumn and dry season, enough water must be irrigated to absorb and promote the emergence of new shoots as soon as possible.

The above-mentioned multi-stage fertilization method is an effective fertilization technology accumulated in the production practice of specific ecological environment during the low temperature and drought period after autumn. However, in the warm winter climate, the problems of this traditional fertilization method are that the amount of fertilization is too heavy in autumn and winter, and the tree vigor is too strong in the later stage. During the physiological differentiation period of flower buds (65,438+February to 65,438+1October of the following year), the tree can not stay temporarily dormant, which is easy to induce the appearance of winter shoots, which is not conducive to the differentiation of flower buds and loses the significance of effectively adjusting the growth vigor and quantity by using fertilization period and amount.

The principle of "attacking the head and supplementing the middle" should be emphasized in reforming fertilization technology. The specific fertilization period is as follows:

Re-applying pre-flowering fertilizer

Fertilization should be carried out in the first half of April when the ear skeleton has been formed, and the dosage is 75% ~ 80% of the annual dosage, with organic fertilizer and quick-acting fertilizer accounting for half each. Such as 10 year old green longan tree, 20 kg of decomposed manure, 30-40 kg of garbage soil, 0.75 kg of urea, 2 kg of calcium superphosphate and 0.5 kg of potassium chloride/kloc-0. 20-year-old trees were applied with 2.5 kg of cake fertilizer, 40 kg of manure, 0.6 kg of urea/kloc-0, 3 kg of calcium, magnesium and phosphorus and 2 kg of potassium chloride. According to Liang Zijun's research (1987), about half or two-thirds of fertilization is spent on fruits at this time. Therefore, reapplication of pre-flowering fertilizer can timely supplement the nutrient deficiency in the late flowering stage of trees, ensure the nutrients needed for the growth and development of young fruits, and play a significant role in alleviating the second physiological fruit drop, promoting fruit growth, increasing the yield of the current year and promoting summer shoots. Moreover, summer shoots are good base branches for sprouting autumn shoots and fruiting mother branches, and popularizing enough excellent summer shoots also plays an important role in preventing fruit bearing in different years. Pre-harvest fertilizer is generally applied 10 ~ 15 days before fruit harvesting, and the dosage is 20% ~ 25% of the annual consumption. Generally, available nitrogen fertilizer is the main fertilizer, with urea of 0.8 ~ 1 kg for annual trees and 0.4 ~ 65438 for 20-year-old trees. At this time, it is necessary to avoid applying compound fertilizer and other after-effect fertilizers or granular fertilizers, so as not to promote winter shoots, and not to spend or spend less in the second year. The role of this fertilization is to restore tree vigor, promote autumn shoots and cultivate fruiting mother branches, which is related to whether it can blossom and bear fruit in the next year. Pre-harvest fertilizer should be applied to old and weak trees and multi-fruit light trees before 15 days to accelerate the recovery of tree potential and promote the emergence of autumn shoots after harvest.

In recent years, Guangdong and Guangxi have advocated and popularized the second autumn shoot picking as the fruiting mother branch in the high and stable yield cultivation of Zhuangqingshu longan, and achieved certain stable yield results. The key to cultivate strong autumn shoots after harvest lies in early development and early enrichment. In order to cultivate early-maturing autumn shoots, measures should be taken in cultivation, such as timely harvesting, changing post-harvest fertilizer into pre-harvest fertilizer, pruning buds and controlling pests and diseases. The specific fertilization method is as follows:

Before fruit picking 10 ~ 15 days, spray 1 times decomposed bran water or manure water containing chicken and duck manure 20 ~ 25 kg, compound fertilizer 1.5 ~ 2 kg and urea 0.5 ~ 1 kg on the canopy drip irrigation line. 30-50g of boric acid (borax).

In the producing areas where the autumn shoots after the second harvest are used as fruiting mother branches, fertilizer 1 ~ 2 times should be applied before and after the first harvest, urea 0.5 ~ 1 kg should be sprayed when the new branches sprout, and compound fertilizer 0.5 ~ 1 kg should be sprayed when the new branches turn green, but after the second bolting, nitrogen fertilizer can be applied separately.

Topdressing outside the roots, spraying foliar fertilizer (such as compound nucleotide, 0. 1% ~ 0.2% chlorhexidine, or 0.2% potassium dihydrogen phosphate +0. 1% zinc sulfate) every time the new shoots turn green.