How to apply winter fertilizer to citrus? Master the correct fertilization method

After “Start of Winter”, once the citrus harvest is complete, seizing the opportunity to promptly apply winter fertilizer is of great significance for the healthy growth of citrus trees and for ensuring stable yields, high quality and high output.

The winter fertilizer applied after fruit harvest is also the base fertilizer for citrus, and its fertilizer dosage should account for 50%--70% of the total annual fertilizer application. The main significance of applying winter fertilizer is:

(1) After a high-yielding citrus plant is harvested, too many nutrients are consumed and need to be replenished.

(2) The organic fertilizer applied into the soil slowly decomposes under the activity of microorganisms, which helps citrus gradually absorb and utilize it under the conditions of slowed winter growth and weakened root absorption capacity, allowing the tree to accumulate more organic nutrients for the needs of budding and flowering the following spring.

(3) It can help the citrus tree recover its vigor as quickly as possible after fruit harvest.

(4) It has a good leaf-preserving function, prolongs leaf lifespan, and prevents citrus from dropping leaves in winter.

(5) It is beneficial for stable and high yields of citrus trees and improves quality.

(6) It greatly enhances the citrus tree's ability to resist freezing and drought. Winter fertilizer should be mainly organic fertilizer. For each mature citrus tree, apply 100--200 jin of decomposed cattle and pig pen manure, 100--200 jin of decomposed turf soil, 3 jin of cake fertilizer, 4 jin of phosphate fertilizer, 3 jin of potassium fertilizer, and 3--4 jin of lime. Alternatively, while applying organic fertilizers such as crop straw, garbage, and pond mud, apply 3 jin of cooked beans, 3 jin of dried cake, 3 jin of phosphate fertilizer, 1 jin of urea, and 3--4 jin of lime per tree.

The main fertilization methods are:

(1) Dig arc-shaped or ring-shaped deep trenches along the outer edge of the tree canopy, with a trench depth of about 50 cm. The trench width depends on the amount of fertilizer, and the cut roots should be trimmed smooth. When digging trenches, the surface soil and subsoil should be piled separately, and organic fertilizers such as cattle and pig pen manure, turf, and dried cake should be applied into the lower layer, while nitrogen chemical fertilizer should be placed in the upper layer. Trees with dark green leaves or a large fruit load should appropriately increase phosphorus and potassium fertilizer. Weak-looking trees should appropriately increase quick-acting nitrogen fertilizer. When filling the trench, first fill in the more fertile surface soil, and put the subsoil on the surface.

(2) Radial trench fertilization. According to the size of the tree canopy, open 4--6 radial trenches along the direction of horizontal root growth. The trench bottom should be shallower near the main trunk and deeper toward the extension beyond the canopy projection. This method distributes fertilizer over a wider area than ring trench fertilization, and the fertilization position can be changed every other year, expanding the fertilization area and promoting root absorption. It is especially suitable for mature citrus orchards. Winter fertilizer should be applied no later than mid-December. Before freezing arrives, it is best to carry out two foliar topdressings; spraying 0.4% urea plus 0.3% monopotassium phosphate, etc., gives better results.