What are some rationalized suggestions for the cultivation and management of Dongshi early pomelo?

  1) Soil management. In young orchards, attention should be paid to intercultivation and weeding, interplanting green manure crops, soybeans, peanuts, etc., deep plowing to improve the soil, and cleaning the orchard soil.

  ① Intercultivation and weeding can prevent surface compaction, loosen the soil, eliminate weeds, and reduce the occurrence of pests and diseases. Intercultivation and weeding can be carried out in combination with deep plowing and earthing up.

  ② Interplanting green manure crops, peanuts, soybeans, white rice beans, etc. in the orchard can increase soil organic matter after being turned under green. Where labor permits, watermelons and vegetables may be intercropped, but sweet potatoes should not be planted.

  ③ Deep plowing and earthing up: ensure there are beds and furrows, clean the orchard, and after fruit harvest thoroughly remove diseased pests, fallen leaves, dead branches, weeds, and parasitic plants on tree trunks such as lichens, moss, and dodder, then burn them.

  ④ Rational fertilization: because the tree canopy is tall and large, with thick branches and luxuriant leaves, large fruit, a long fruit-bearing period, and a well-developed root system, fertilization is essential to achieve high yield. Organic fertilizers include human excreta and urine, barnyard manure, cake fertilizer, farmyard manure, miscellaneous soil manure, green manure, etc. Chemical fertilizers should be applied in a rational combination. Pomelo has a certain demand for magnesium fertilizer, which should be noted when fertilizing.

  2) Fertilization of young trees. Young trees should be focused on promoting vegetative growth and expanding the canopy, mainly with nitrogen fertilizer, combined with an appropriate amount of phosphorus and potassium fertilizer. One month after planting, a light fertilizer application can be made. Generally, fertilizer is applied more than 6 times throughout the year. From February to September, fertilizer can be applied once a month. The fertilizers are mainly human excreta and urine, pig and cattle manure, cake fertilizer, etc., combined with urea, superphosphate, etc. According to the concentration of the original fertilizer and the dry and wet conditions of the soil, human excreta and urine can be diluted with 1 to 2 times water. When applying chemical fertilizers in combination, trenches can be dug on both sides of the young tree at the drip line outside the canopy and the fertilizer applied. Apply 2.5 to 5 kg of the above organic fertilizer per plant, apply 50 g of urea after rain, and in spring and autumn apply bone meal, calcium magnesium phosphate, etc., 150 to 250 g per plant, along with decomposed fertilizer. Then cover and fill level. In the second and third years, as the canopy gradually expands, the fertilizer concentration can be increased, and fertilizer is applied 4 to 5 times throughout the year.

  3) Fertilization of mature trees. Once pomelo trees enter the fruiting stage, fertilization can not only promote vegetative growth, but more importantly can ensure nutrients for reproductive growth. The timing, frequency, and amount of fertilization should vary according to different conditions such as climate, soil, tree vigor, and yield. Generally, fertilizer is applied 4 times a year.

  4) ① First application: spring bud fertilizer. One to two weeks before the climate warms and the pomelo trees sprout, usually in early February, mainly with quick-acting nitrogen and phosphorus. Apply 30 kg of human excreta and urine, 0.2 to 0.5 kg of nitrogen fertilizer, and 1 kg of phosphorus fertilizer per plant, accounting for 20% of the annual fertilization amount.

  ② Second application: fruit-preserving fertilizer. From late April to early May, to supplement the excessive consumption of nutrients by pomelo trees and reduce fruit drop, apply 20 kg of human excreta and urine and 1.5 kg each of phosphorus and potassium fertilizer per plant. A 1% urea and 2% superphosphate extract can also be used for foliar topdressing, accounting for 10% of the annual fertilization amount.

  ③ Third application: fruit-strengthening fertilizer. Apply in June to July when the fruit expands. Apply 15 to 25 kg of human excreta and urine per plant, combined with 1 to 1.5 kg of cake fertilizer, 2 kg of bone meal, and 1 to 2 kg of nitrogen fertilizer, accounting for 20% of the annual fertilization amount.

  ④ Fourth application: post-harvest fertilizer. Apply from late October to December, entirely organic fertilizer, combined with phosphorus and potassium fertilizer. Apply 25 kg of human excreta and urine, 50 kg of miscellaneous soil manure, and 2 to 3 kg of phosphorus and potassium fertilizer per plant, accounting for 50% of the annual amount. If there is too much fruit, apply quick-acting chemical fertilizer 10 to 15 d before harvest, combined with irrigation.