Cultivating healthy seedlings and implementing fertilization in nurseries are important links. During the growth of seedlings, fertilisers are often used as quick-acting fertilizers or decomposed organic fertilizers to timely supply various nutrients needed for different growth stages of seedlings to meet the growth needs of seedlings.

According to the characteristics of fertilizer required for different growth stages of seedlings. Seedling growth is generally divided into four stages: seedling stage, seedling stage, fast growth stage, and hardening stage. The nutrient source of seedlings during the seedling stage is mainly based on the nutrients stored inside the seeds. The seedlings at the seedling stage are more sensitive to nitrogen and phosphorus. Generally, nitrogen fertilizer is applied mainly to promote seedling maintenance and root growth. Fast-growing period is the period when the seedlings grow most vigorously. It needs the most fertilizer and water, can increase the amount and frequency of nitrogen fertilizers, and apply phosphorus and potassium fertilizers in proportion to promote nitrogen absorption and seedling growth. When the seedlings are gradually hardened in the upper and lower parts of the seedlings, they must prevent leggy, stop using fertilizers, and increase seedling resistance.

Use suitable fertilizer types. Fertilizer topdressing generally uses quick-acting fertilizer or decomposed human waste. The types of quick-acting fertilizers used in nurseries are urea, ferric sulfate, ammonium chloride, potassium chloride, and superphosphate. Fertilizers must be completely crushed into powder and should not be applied in blocks. To cultivate grass flower nurseries, avoid application of ammonium bicarbonate, because this fertilizer is highly volatile, especially when applied under high temperature, volatile ammonia easily burns the leaves of the seedlings of grass flowers. If a large amount of ammonium bicarbonate is applied, the seedlings will grow soft and reduce stress resistance.

Select the appropriate fertilization method. Seedlings fertilizer can be divided into dry and wet casting methods. The dry method is to fertilize the fertilizer. The depth of the furrow should be in the distribution layer of the root system. It should be applied around the fibrous roots and should not be close to the cadres. Strong roots, deeper distribution of seedlings, fertilizer should be deep, range should be large, such as pine, ginkgo, acacia, skunk, etc.; shallow root seedlings such as flowering shrubs, France Tong, etc., fertilizer should be shallow, range should be small. Wet application method is to fertilize the fertilizer to water and evenly apply it on the nursery ground. Fertilizer should grasp the characteristics of fertilizer. Nitrogen fertilizer has a strong mobility in soil, and it penetrates into the root distribution layer with shallow application. It is easily absorbed by seedlings. The mobility of potash fertilizer is poor, and the mobility of phosphate fertilizer is worse. It is advised to apply the deepest distribution to the root system of seedlings. When fertilizer is used as a base fertilizer, the fertilizer effect is slower and should be applied deeper; if the top dressing is quicker, it should be applied lightly. According to the weather conditions, the number of fertilizers and the amount of fertilizers are determined. High temperature, absorption of fertilizer; low temperature, seedlings absorb less. When the weather is clear and the soil is dry, fertilization is conducive to the absorption of seedlings. In rainy days, the root system of seedlings absorbs water slowly. Not only is the nutrients not easily absorbed, but the fertilizer components are also easily washed away by rain, causing waste.

Seedling fertilization. Mainly based on seedling species, seedling age, seedling density and growth potential to determine the fertilization measures. For example, conifers need more nitrogen than broad-leaved species and require less phosphorus. Generally, annual seedlings need more N and P in the initial stage of growth to promote the growth of young roots; a large amount of nitrogen, phosphorus, potassium, and other elements are needed in the fast growing period; potassium is the main ingredient and phosphorus is the auxiliary in the later growth stage to promote young growth. Stem lignification. Compared with nursery seedlings, container seedlings cannot be applied to basal fertilizer, otherwise it will cause the concentration of certain elements to be too high and cause dead seedlings. Generally just the right amount of compost is applied, and the effect of topdressing is also good, that is, applying the quick-acting fertilizer in combination with container seedling irrigation. Fertilizer for container nursery is usually formulated as a mixed fertilizer containing a certain proportion of nitrogen, phosphorus, and potassium nutrients at a concentration of 1:200 and sprayed or rooted through an irrigation system.

Root dressing outside. Outside the root dressing is in the growth period of seedlings will be a solution of available fertilizer directly on the leaves of seedlings, so that the fertilizer gradually infiltrated into the leaves of synthetic seedlings much needed nutrients for growth. In general, the young leaves are older than the leaves, and the leaves are more water-absorbing than the leaves, and the absorption rate is also high. Therefore, when the spray is applied, the back of the leaves must be sprayed evenly. In seedling fertilizer, common foliar fertilizers include urea, potassium dihydrogen phosphate, and various kinds of foliage treasures. When using them, the concentration should be strictly controlled so as to avoid burning the leaves. It is best to spray on cloudy days or before 10 o'clock in the morning and after 4 o'clock in the afternoon, so as to avoid high temperatures and rapid concentration of the solution, affecting the effect of spraying fertilizer or causing phytotoxicity.

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