Scientific fertilization and management of citrus trees is essential for their growth and fruiting. In the life cycle of citrus trees, including three stages: young trees, first-fruiting trees and fruiting trees, differentiated fertilization strategies and scientific management measures are required to ensure the healthy growth and high yield of trees. The following is a detailed introduction to the fertilization and management of citrus trees.
1. Fertilization
1. Young and first-bearing trees
For newly planted young and fruiting trees, special attention needs to be paid to fertilization to promote their growth and development. The specific fertilization methods are as follows:
Once a month in March ~ August: apply thin human feces or urea solution on the ground once a month, mainly nitrogen. Each plant can be 50 grams of urea plus 50~100 grams of potassium sulfate, dissolved in 6~8 kg of well-rotted thin manure or water, and then poured at the crown drip line.
Other young trees (including first-fruiting trees): apply fast-acting thin fertilizer to the ground 1 week before each shoot extraction, and at the same time, combined with pest control, carry out foliar top dressing once every 15~20 days. When topdressing, nitrogen and potassium fertilizers are the main fertilizers, and the ratio of nitrogen, phosphorus and potassium (N:P2O5:K2O) is 1:0.3:0.5. For the first-fruiting tree, the ratio of nitrogen, phosphorus and potassium (N:P2O5:K2O) should be between 1:(0.4~0.6) :(0.7~1). As the canopy expands, the amount of fertilizer should be increased gradually.
2. Fruit tree
For fruiting trees, different fertilization strategies are required for different varieties and canopy states:
Early-maturing and extra-early-maturing varieties such as Wenzhou mandarin oranges, as well as trees with many fruits and weak trees, can be applied with fruit-strengthening fertilizer before the second physiological fruit drop is basically over (late June). You can choose organic and inorganic compound fertilizer, multi-compound fertilizer or ternary compound fertilizer, and add organic fertilizer such as well-rotted cake fertilizer or column fertilizer. The amount of fertilization this time accounts for about 30%~40% of the whole year. Generally speaking, for orange trees with a yield of about 50 kg per plant, it is recommended to apply 15~20 kg of organic fertilizer (manure) (or 1.5~2 kg of cake fertilizer), plus 0.5~1 kg of urea and 0.5 kg of potassium sulfate or 0.5~1 kg of nitrogen, phosphorus and potassium ternary compound fertilizer. When fertilizing, it is mainly applied in furrows or holes, and the fertilization depth is about 10~30 cm. It is best to apply fertilizer at the beginning of the sunny day after the rain, dry application after the rain during the rainy season, and irrigation fertilization during the dry season, or immediately after fertilization.
2. Water management
April ~ June is the key period for citrus shooting, flowering, and fruiting, so water management is particularly important. During this period, the water requirement of citrus trees is comparatively greater. Here are some recommendations for moisture management:
When there is a slight wilting of the leaves on a cloudy day, high temperature and drought, and the leaves cannot return to normal in the evening, irrigation or watering should be carried out in time.
When the spring rains are continuous or the rainfall is heavy during the plum rainy season, the ditches should be dredged in time to prevent the orange orchard from accumulating water.
3. Shoot fruit management
Shoot management includes flower thinning and shoot control, nutrient spraying and reasonable fruit retention.
Thinning the flower and controlling the tip
: Depending on the growth and amount of flowers of the citrus tree, different flower thinning and tip control measures are required. For multi-flowered trees with moderate tree potential, some leafless branches can be thinned at the bud stage, and some of the spring shoots that are too long can be removed. In the full flowering and late flowering periods, it is necessary to shake the flowers once to remove deformed flowers, petals and young fruits with poor pollination and fertilization. For primary trees or weak flowering trees, the spring shoots in the middle and upper part of the canopy and the periphery can be thinned during the peak spring shoot period, and the amount of thinning shoots can account for 30%~50% of the amount of new shoots. In addition, the new shoots inside the canopy should keep 4~6 leaves and then top. When the spring shoots are 4~5 cm long, you can also use 15% paclobutrazol wettable powder 200 times liquid spray on the new shoots to control the growth of the shoots.
Spray nutrient solution
: For citrus trees with many flowers and weak trees, you can spray foliar fertilizer every 10~15 days from the flower bud stage to supplement trace elements such as boron, zinc, iron, manganese, magnesium, etc. For some trees with strong strength and low flowers, fruit preservation can be carried out when the flowers are 2/3 of the time.
Ryōri Ruka
: In order to ensure a stable and good yield of citrus trees year after year, fruit thinning is required. Fruit thinning is generally divided into two parts: the first is to remove small fruits, diseased fruits, deformed fruits and dense fruits at the end of the first physiological fruit drop and the size of young fruits is clear. The second time is to properly thin the excess fruit according to the leaf-fruit ratio requirements of different varieties after the fruit is set. Fruit thinning in citrus trees helps to keep the fruit uniform in size and improve the quality of the fruit.
Through the above scientific fertilization and management methods, the yield and quality of citrus trees can be effectively improved, and the steady development of the citrus industry can be ensured.