How and when to apply fertilizer to grapefruit

Fertilization methods: soil fertilization is generally used for grapefruit, ring and disk fertilization methods can be selected for young trees, strip furrow, radial furrow, hole and whole garden fertilization methods can be selected for adult trees, and foliar fertilizer can be sprayed for topdressing outside roots. Young tree fertilization time: planting 1-3 years of young trees, can be applied in March-August quick-acting fertilizer, in October application of decomposed manure, compost, dry cake, etc. Fertilization time of adult trees: quick-acting fertilizer can be applied to adult trees before germination.

1. Pomelo fertilization method

1. Soil fertilization

Young trees can be fertilized in rings and disks, and adult trees can be fertilized in furrows, radial furrows, holes, and whole gardens.

2. Topdressing outside roots

(1) In addition to soil fertilization, grapefruit can also be sprayed with foliar fertilizer. Foliar topdressing is to absorb nutrients through stomata. This method uses less fertilizer and has better effect. However, it cannot replace soil fertilization. Spraying fertilizer should be selected at the new shoot color and young fruit stage. It can be sprayed on the back of leaves.

(2) In the summer high temperature, can be carried out in sunny days, generally in the dew dry before 10 a.m. and after 4 p.m., when the temperature is 18-24℃ spray.

(3) The concentration of various fertilizers is urea 0.2%-0.5%, urine 5%, zinc oxide 0.2%, boron 0.1%-0.2%, ammonium molybdate 0.2%, ferric citrate 0.1%-0.2%, magnesium nitrate 0.5%, potassium nitrate 0.3%-0.5%, potassium sulfate 0.1%-0.3%+0.2% hydrated lime, potassium dihydrogen phosphate 0.2%-0.4%, calcium superphosphate leaching solution 1%, Zinc sulfate 0.1%-0.2%+0.1% hydrated lime, magnesium sulfate 0.2%-0.4%+0.2% hydrated lime, manganese sulfate 0.1%+0.1% hydrated lime.

II. Fertilization time of young trees

1. Young trees 1-3 years after planting are mainly used to cultivate strong root groups, promote new shoots, form tree crowns as soon as possible, and enter the fruiting period in advance. During this period, nitrogen, phosphorus and potassium can be applied. Young trees need to be fertilized many times due to their few and weak root groups, shallow distribution and weak absorption capacity.

2, can choose in March to August, every 15-20 days to apply a quick-acting fertilizer, conducive to promoting the growth of spring, summer, autumn three times, can be about 20 days before each shoot, apply 1-2 times to promote the shoot fertilizer, shoot leaves after the beginning of green, and then apply a fertilizer, conducive to promoting the shoot mature.

3, generally after mid-September, it is not appropriate to apply quick-acting nitrogen fertilizer, avoid late autumn shoots, in October, can apply a base fertilizer, mainly can apply decomposed manure, compost, dry cake, etc., each plant can be applied decomposed pig manure 25-30kg, or cake fertilizer 1- 1.5 kg, conducive to enhancing tree vigor, improve plant resistance.

III. Fertilization time of adult trees

1. The fruiting mother branches of adult trees are mainly spring shoots, so quick-acting fertilizer can be applied before germination, which is conducive to promoting the growth of spring shoots, promoting the vigorous function of old leaves and delaying defoliation, improving the nitrogen content of leaves, making flower organs develop completely, forming leafy fruit branches, and strengthening shoots and flowers. Fertilization can be selected 20-30 days before germination.

2. The annual tree is to prune excessive flowers and increase the yield of vegetative branches. Generally, spring fertilizer can be delayed to summer flowering, during which the amount of nitrogen fertilizer can be appropriately increased. The annual tree can be applied in advance to early spring, and the amount of fertilizer should not be too much, which is conducive to controlling excessive flowering of vegetative branches and improving its fruit setting rate. Nitrogen, potassium and phosphorus fertilizer can be applied before flowering, accounting for about 20% of the total fertilizer application amount of the whole year.