Avocado consumes a lot of fertilizer, but the proportion and dosage of fertilizer should be determined according to soil fertility, tree age, plant growth and yield. Galen and others suggested that mixed fertilizer should be applied every1~ 2 months in the first year after planting, and the amount of fertilizer should be gradually increased from 1 10g per plant to 450g, and then it should be applied 3 ~ 4 times a year. The mature trees were applied with pure nitrogen and potassium at a rate of165 ~ 225 kg /hm2 for 3 ~ 4 times (< 300 plants/hm2). The ratio of nitrogen, phosphorus, potassium and magnesium applied to young trees is1∶1∶1∶ 0.33; The ratio of mature trees is 1∶0.4∶ 1.2∶0.4. In California, USA, the nutritional analysis was carried out with mature and healthy leaves of non-hanging fruit branches, and the normal nutritional value of pear trees was determined (see Table 2-22).
On the basis of planting hole base fertilizer, China adopted a small number of fertilization schemes in the first year of planting, mainly liquid nitrogen fertilizer. The mature trees are mainly nitrogen and potassium fertilizers, which are applied 3-4 times a year, in February-April, April-May and July-September respectively. Phosphate fertilizer is mixed with organic fertilizer and applied once before and after fruit picking.
Table 2-22 Diagnostic Indicators of Nutrients in Adult Leaves of Avocado
Source: Frank, D.Koch, AVOCADO GROWER'S HANDBOOK, 1983.
Fertilization of avocado should avoid damaging roots, and it is appropriate to apply it by spreading, water or shallow ditch.
2. Irrigation
Avocado is very sensitive to soil drought, so it is necessary to keep the root zone soil moist all year round. Once water is lacking, physiological functions will be hindered, trees will be weak, and even leaves and fruits will fall. Especially during flowering and fruit development, sufficient water is needed. Irrigation in drought is based on the principle of soaking the soil. If excessive irrigation causes excessive soil moisture, the effect will be counterproductive and even aggravate the occurrence and spread of root disease.
3. Weeding and mulching
Weeding should prevent root injury, it is best to weed the young trees manually in the tray, loosen the soil shallowly in the intertillage, and plant leguminous mulch crops between rows to inhibit the growth of weeds, reduce water evaporation and increase soil fertility. Herbicide should be used to weed without intercropping. 4. Plastic pruning
From the young age, the top should be picked when the seedling height is about 80 ~100 cm to promote the growth of lateral branches, and then the top of each branch should be picked again at a length of about 50 ~ 60 cm to cultivate a crown with uniform distribution around, moderate density and good light transmission. Pruning is mainly to cut off dead branches, diseased branches, weak branches, long branches, cross branches, drooping branches, too dense branches and other branches. Large scissors should be sealed to prevent rot and illness.