Key techniques of returning Yang Fertilizer to Citrus trees in Autumn

Key techniques of applying "returning Yang Fertilizer" to Citrus trees in Autumn

In autumn, fruit trees changed from aboveground growth to underground root growth, while citrus trees consumed a lot of nutrients after sprouting, branching, flowering and fruiting. "returning Yang Fertilizer" was applied in time before and after fruit harvesting. It plays an important role in tree recovery, overwintering cold prevention and high quality and high yield in the second year.

1 the time of fertilization should be "early"

There are two growth peaks of citrus roots in spring and autumn in a year, and the time of applying base fertilizer in autumn should be as early as possible, and the most suitable time for citrus trees is from mid-late October to the end of November. Reasons: (1) suitable soil temperature, good soil moisture, conducive to fertilizer ripening, easy to be absorbed and utilized by roots. (2) the injured root is easy to heal, and can grow a new root with a length of 1 cm to 2 cm, which greatly improves the fertilizer efficiency. (3) early application of base fertilizer can provide a variety of nutrients for fruit trees for a long time, enhance the function of autumn leaves, increase the storage weight of trees, promote the fullness of branches and buds, and improve the stress resistance of trees.

(2) the types of base fertilizers should be "more".

The content of organic matter in ideal soil should be 5%-7%. At present, the content of organic matter in Chenggu citrus orchard is about 1%, resulting in soil consolidation and underdeveloped capillary roots (figure 1). Organic fertilizer is mainly recuperated and rooting, which is generally applied as base fertilizer. The fertilization is mainly organic fertilizer and late-acting fertilizer, such as mature farm fertilizer or commercial organic fertilizer, properly combined with available nitrogen, phosphorus and potassium compound fertilizer, and the application amount of organic fertilizer should account for more than 50% of the total annual fertilization. Combined with the selection of high-efficiency, compound foliar fertilizer, or 0.5% urea + 0.3% potassium dihydrogen phosphate to supplement foliar fertilizer is better.

Fig. 1 low content of soil organic matter and underdeveloped capillary roots

3The quantity should be "full".

Adequate base fertilizer is the basis of strong, high and stable yield of citrus trees. Results the initial application rate of high quality farm manure was 2000kg / mu, mixed compound fertilizer 20kg / mu, 4000kg / mu and 40kg / mu in full fruit stage.

(4) the depth of applying base fertilizer in autumn should be "suitable".

The absorbing roots of fruit trees are mostly concentrated in the soil with a depth of 10 cm to 60 cm (figure 2), and the most suitable depth of fertilization should be 20 cm to 30 cm. Fruit growers are accustomed to shallow fertilization, which makes most of the mineral nutrients such as nitrogen, phosphorus and potassium remain in the surface soil, and makes the roots float up to the surface soil, which is extremely vulnerable to freezing, drought, waterlogging and other harms. It is easy to hurt the roots when ploughing, resulting in the decrease of stress resistance of fruit trees and poor fruit quality. Through the combination of deep turning and deep application of organic fertilizer, the fertilizer can be mixed to the middle and lower layer, which is convenient for root absorption and utilization.

5 pay attention to the application method

Fertilizer should be applied to the centralized distribution layer of the root system, that is, to the branch extension 20 cm to 40 cm deep (figure 3).

Fig. 2 Distribution range of good root growth

Fig. 3 range of fertilization depth

Young trees combined with hole expansion, ditch expansion, using ring ditch application or strip ditch application, expanding outward every year until the whole garden is turned over. As a result, the tree should be applied in holes or furrows (figure 4), and it can also be spread in the whole garden. This method is used alternately every other year.

Fig. 4 annular acupoint application

6 fertilization should be combined with watering

Watering immediately after fertilization will cause a lot of nutrient loss, at the same time, the root system is vulnerable to fertilizer damage, affecting the normal growth of fruit trees, so it is not suitable to water immediately after fertilization. However, the base fertilizer should continue to decompose after being applied, first absorbed by the soil, and then slowly released when absorbed by the root system, which requires a certain amount of water. Therefore, watering before fertilization or watering after half a month is recommended. Fertilizing and watering should be combined.