How to fertilize Lagerstroemia speciosa

Topdressing: It is a measure to apply quick-acting fertilizer during the growth and development of Lagerstroemia indica seedlings. The purpose is to supplement the nutrient requirements of Lagerstroemia indica seedlings in the vigorous growth period in time, promote the growth and development of seedlings and improve the quality of seedlings.

Topdressing principle: To achieve reasonable topdressing, we must comprehensively consider the weather, soil and Lagerstroemia indica seedlings, and look at fertilization, that is, "look at the sky, the ground and the trees", and apply nitrogen, phosphorus, potassium and trace elements in proportion. Among them, fertilization depends on the weather, that is, less application and more application when the climate is hot and rainy. When the climate is cold, apply fully decomposed organic fertilizer as topdressing. When the temperature is higher than normal, the first topdressing time can be advanced. Fertilization by looking at soil means that different soils contain different types and quantities of nutrient elements, so it is necessary to measure soil and fertilize, and apply whatever elements are lacking. If the soil contains enough nitrogen, more phosphorus and potassium fertilizers should be applied. Different soil textures have different nutritional conditions. When applying chemical fertilizer, the amount of sand should be less, and the amount of clay can be increased appropriately. For the same amount of fertilization, sandy soil should be applied several times, and clay can increase the amount of fertilization each time and reduce the number of fertilization. Depending on the fertilization of seedlings, different types of seedlings have different requirements for various nutrient elements, and flowering shrubs need more phosphorus than ordinary tree species. For example, Lagerstroemia indica seedlings have different requirements for nutrients at different development stages. In the initial stage of growth, more nitrogen and phosphorus are needed, and in the rapid growth stage, a lot of nitrogen, phosphorus and potassium are needed. In the late growth stage, potassium is the main factor, supplemented by phosphorus, so as to promote the lignification of branches and stems and enhance the resistance of seedlings to the environment. The growth of Lagerstroemia indica seedlings is different, and the demand for nutrients is different. It doesn't need fertilization to grow vigorously, but it is necessary to analyze which elements are missing in the fertilizer and then replenish them in time.

(2) Types, dosage and time of topdressing: Top dressing is commonly used with quick-acting fertilizers such as human excrement and urine, plant ash, fireclay and chemical fertilizer. The amount of fertilization should increase with the growth of seedling age, from less to more, from thin to thick, timely and appropriate. Topdressing once every 10 ~ 15d, topdressing after sowing several true leaves of Lagerstroemia indica seedlings, and topdressing for about 5 ~ 6 times in the whole growth period. Monthly dose: thin stool

3 000~4

500kg/hm2, diluted with water; The fertilizer is 45-75kg /hm2. Topdressing of cutting seedlings should be carried out after rooting or germination of new roots, and the initial concentration should be diluted, and then the concentration will gradually increase. Large seedlings need a large amount of fertilizer, which should be decided according to phenology. The specific topdressing situation of Lagerstroemia speciosa seedlings is as follows: in the early growth stage, the leaves are completely spread out, and the time is around the middle and late May. At this time, a small amount of topdressing should be carried out in stages, mainly nitrogen fertilizer. For example, the amount of human decomposed and diluted manure is 6.

000~7

500kg/hm2, mixed with water. Flourishing season: the time is about June to August, and fertilization is generally at least once a month. Thick manure can be applied according to the above dosage, and nitrogen fertilizer can also be applied, and the dosage is 150 ~ 187.5 km2/hm2. Robust growth period: from August to September, most Lagerstroemia rubra seedlings enter robust growth period, so nitrogen fertilizer is generally not suitable. In order to increase the dry matter weight, promote tissue maturation and facilitate the overwintering of Lagerstroemia indica seedlings, quick-acting phosphate fertilizer should be mainly applied, and 75 ~ 150k2 calcium superphosphate can be applied.

Late growth stage: from the middle and late June of 10 to February of the following spring, the fertilization time and dosage shall be determined as appropriate. If topdressing alone, phosphate fertilizer should be the main fertilizer, with a small amount of nitrogen fertilizer and potassium fertilizer. The production of Lagerstroemia indica seedlings is often combined with the application of slow-release fertilizers, which makes Lagerstroemia indica seedlings overwinter safely and lays the foundation for the growth and development in the next spring.

(3) Topdressing method. Topdressing should be carried out on sunny or cloudy days when the soil is slightly dry, and should not be carried out on rainy days to avoid nutrient loss. Avoid topdressing at high temperature at noon, and don't let the fertilizer touch the seedlings or leaves. Topdressing generally adopts two methods: soil topdressing and root topdressing. ① Topdressing of soil: When applying human manure as topdressing, Lagerstroemia indica seedlings should be diluted in large quantities and sprinkled on the seedbed, and it is best to irrigate a small amount after application, or it can be poured into the seedbed together with irrigation. Lagerstroemia indica seedlings can be directly applied around the rhizosphere and covered with soil after application. Fertilizer topdressing can be divided into dry application and wet application. The former is to spread the chemical fertilizer evenly among the seedlings, and then use a shallow hoe or first ditch between rows to cover the soil, and then put the chemical fertilizer into the ditch to cover the soil. Wet application is to dissolve the fertilizer in water, spread it all over, and then water it again after application to avoid burns. (2) Topdressing outside the roots: Spraying the water solution of quick-acting fertilizer directly on the leaves of Lagerstroemia indica seedlings, so that nutrients can gradually penetrate into the body through the stomata or cuticle of the leaves to meet the needs of Lagerstroemia indica seedlings. Topdressing outside the root can prevent the fertilizer from being fixed or leached by the soil, with less fertilizer consumption and quick effect, but it is easy to dry after foliar spraying, and a slightly higher concentration will burn the seedlings. In addition, the leaves can't inhale slow-release fertilizer. At present, topdressing outside the roots is mainly used in the following situations: the temperature rises but the ground temperature is still low, the aboveground parts of seedlings have begun to grow but the roots have not yet moved normally; The seedlings have just been planted, and the root injury has not healed; Seedlings lack a trace element, which will be ineffective after being applied to soil. The concentration and application amount of topdressing outside the root vary with fertilizer types and seedling size. Seedling, generally per hectare

7.5 ~ 15 kg of urea was applied each time, and the concentration was 0.2% ~ 0.5%; 22.5-66.5 kg of calcium superphosphate with a concentration of 0.5%- 1.0% and 7.5-15ks of potassium chloride or potassium sulfate with a concentration of 0.3%-0.5%; Trace element fertilizers are available.

0.25%~0.5%。 The spraying time of Lagerstroemia speciosa leaves is suitable when the atmosphere is humid or cloudy in the morning and evening. For some fertilizers that are not easy to distribute evenly on the leaf surface, a small amount of adhesive can be added appropriately to facilitate the uniform distribution of liquid medicine on the leaf surface. Spray evenly on the front and back of the blade. The spraying times are generally 2 ~ 3 times. If it rains within two days after spraying, spray it after the rain.