Mango soil testing formula fertilization technical points
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June 25 12:55:02, 2025
Fertilization of mango trees is crucial for their healthy growth, high yield, and quality fruit production. For every 1000 kg of fresh mango produced, approximately 1.74 kg of nitrogen (N), 0.23 kg of phosphorus pentoxide (P₂O₅), and 2.0 kg of potassium oxide (K₂O) are required. Among these, potassium is the most needed, followed by nitrogen and then phosphorus. A general fertilizer ratio of N:P₂O₅:K₂O = 1:0.5:0.5–1 is commonly used, but this may vary depending on tree age, region, and yield level. It's important to understand the general guidelines and adjust the application based on local conditions and tree requirements.
**1. Fertilization for Young Trees**
Young mango saplings require fertilization to promote strong vegetative growth, develop a robust root system, increase the number of shoots, and expand the canopy, which lays the foundation for early fruiting and high yields. Nitrogen and phosphorus should be prioritized, with moderate amounts of potash. Organic manure should be applied as much as possible to improve soil fertility and structure.
**(1) Planting Fertilizer**
During planting, organic manure is primarily used, along with a small amount of phosphate fertilizer, placed directly into the planting pit. If the soil is highly acidic, lime should be added to neutralize it. The lime should be evenly mixed into the soil before planting, allowing time for it to react. After 10–15 days, the pit can be filled with organic fertilizer and the tree planted.
**(2) Top-dressing for Saplings**
After the sapling has established itself, top-dressing should be done regularly. This involves applying quick-release nitrogen and phosphorus fertilizers to encourage new root development and shoot growth. Within 1–2 months after planting, new shoots will appear. Once the first flush of shoots emerges, top-dressing can begin. Each time, apply 20 grams of urea or 5 kg of diluted manure per plant. As the tree ages, the amount can gradually increase to 40 grams of urea or 10 kg of diluted manure per plant. In the second year, combine this with an application of 25–50 kg of organic fertilizer and 0.5–1 kg of phosphate fertilizer during fall hole expansion. Additional top-dressing with 0.1–0.15 kg of urea or 0.2–0.3 kg of compound fertilizer per plant is recommended, either through watering or shallow trenches.
**2. Fertilization for Bearing Trees**
Once the tree starts bearing fruit, the goal of fertilization shifts to promoting flower formation, increasing yield, and improving fruit quality. The nutrient needs differ from those of young trees in terms of quantity, type, and timing. Mango trees typically begin to bear fruit in their third year and become productive in the fourth year. During years 4–5, the recommended annual fertilizer application is around 0.4–0.5 kg of nitrogen (equivalent to 0.9–1.1 kg of urea), 0.25–0.3 kg of P₂O₅ (equivalent to 1.6–1.8 kg of calcium magnesium phosphate), and 0.36–0.4 kg of K₂O (equivalent to 0.6–0.7 kg of potassium chloride). After six years of age, the application rates should be adjusted based on yield and tree condition.
There are four key periods for fertilizing mature mango trees:
**(1) Pre-flowering Fertilization**
This occurs about one month before flowering, when flower buds begin to differentiate. In Guangxi, this usually happens in December. Applying nitrogen and potassium at this stage helps promote bud formation. Apply about 20% of the annual dose, such as 0.1–0.2 kg of urea and potassium chloride per plant. If using simple superphosphate, add 1.6–1.8 kg per plant. Foliar sprays of 0.2–0.3% potassium dihydrogen phosphate can also be used, sprayed 2–3 times with a 7–10 day interval.
**(2) Flowering Stage Fertilization**
Mango trees consume a lot of nutrients during flowering. A top-dressing of nitrogen is recommended at this time. Apply 0.1–0.15 kg of urea or compound fertilizer per plant, ideally when 50% of the last shoots begin to bloom. Combining this with foliar sprays of 0.1% borax and 0.2–0.3% potassium dihydrogen phosphate can enhance flower quality. However, if the tree is already vigorous, additional fertilizer may not be necessary.
**(3) Fruit Development Fertilization**
About 30 days after flowering, the fruits start to grow rapidly. At this stage, apply 0.3–0.4 kg of urea and 0.2–0.3 kg of potassium chloride per plant. If no phosphate fertilizer was used earlier, add 1.6–1.8 kg of calcium magnesium phosphate. Foliar sprays of 0.2–0.3% urea and potassium dihydrogen phosphate can also be used, 2–3 times with 7–10 days between applications.
**(4) Post-harvest Fertilization**
After harvesting, the tree requires nutrients to recover and prepare for the next season. Apply 0.2–0.3 kg of urea and 0.1–0.2 kg of potassium chloride per plant. A second application can be made when the last shoot begins to green, combining with organic manure (25–50 kg per plant) and 0.5 kg of compound fertilizer. Foliar sprays of 0.3% potassium dihydrogen phosphate can be applied 1–2 times to support recovery.
**3. Fertilization Methods**
Soil fertilization typically uses two main methods: ring groove and trench application.
- **Ring Groove Fertilization**: Dig a circular or semi-circular groove outside the canopy drip line, about 15–20 cm wide and deep.
- **Trench Fertilization**: Dig two parallel trenches symmetrically outside the canopy each year, 20–30 cm wide and deep. When the trench is deeper than 60 cm, it can be expanded for better nutrient absorption. After applying the fertilizer, cover the soil to ensure proper contact.