Spring marks the beginning of a new growth cycle for citrus trees. Just like deciduous trees it is essential to plan an annual fertilization program during this period to ensure optimal tree health and high yield.
Understanding Nutrient Dynamics in Early Spring
During winter, many citrus trees enter a semi-dormant state with minimal growth in both the canopy and root system. The combination of dormancy and cool, waterlogged soils reduces root activity, limiting nutrient uptake. As a result, citrus trees rely on stored nutrients, which can become depleted by early spring. This often leads to ‘winter yellowing’—a condition where leaves turn yellow despite adequate soil nutrients, primarily due to nitrogen deficiency.
To prevent deficiencies and kickstart the new growth cycle, it is crucial to conduct soil tests and leaf analyses at the beginning of the season. This ensures an accurate assessment of the tree and soil nutrient status, forming the basis for an effective fertilization strategy.
Nutritional Needs for Spring Growth
Following dormancy, citrus trees undergo vigorous vegetative growth, which is critical for strong leaf flush, flowering, and fruit set. A well-balanced nutrition plan is essential at this stage to support these processes.
Recommended nutrient supply during the vegetative growth stage:
- Nitrogen (N): Apply approximately 15% (45 Kg/ha) of the annual requirement (300 Kg/ha).
- Phosphorus (P₂O₅): Apply approximately 25% (24 Kg/ha) of the annual requirement (84 Kg/ha).
- Potassium (K₂O): Apply approximately 15% (22 Kg/ha) of the annual requirement (150 Kg/ha).
- Micronutrients: Spring is an ideal time for a foliar spray to enhance fruit set, chlorophyll production, photosynthesis, and leaf growth. Zinc deficiencies are particularly common in citrus orchards, while manganese, iron, and boron deficiencies also occur but less frequently.
Using Multi-K is preferable because the roots will favor nitrate uptake at this growth stage, and potassium nitrate is the best source of potassium for citrus.
The following table taken from Haifa's NutriNet tool for crop nutrition management, shows the annual nutrient requirements of citrus.
| Stage | Days | Macronutrients (kg/ha) | Secondary nutrients (kg/ha) | Micronutrients (gram/ha) | |||||||||
| N total | P2O5 | K2O | CaO | MgO | SO4 | Fe | Mn | Zn | Cu | Mo | B | ||
| Feb-Mar - vegetative growth | 60 | 55 | 15 | 25 | 0 | 5 | 0 | 57 | 57 | 27 | 23 | 1.5 | 15 |
| Apr-May - flowering to fruit set | 60 | 77 | 21 | 35 | 0 | 7 | 0 | 129 | 129 | 62 | 52 | 3 | 30 |
| Jun-Sep - fruit development | 120 | 118 | 48 | 164 | 48 | 12 | 0 | 321 | 321 | 153 | 130 | 7.5 | 75 |
| Oct-Jan - harvest | 120 | 36 | 12 | 48 | 0 | 0 | 0 | 16 | 16 | 8 | 6.5 | 0.4 | 4 |
| Total | 360 | 286 | 96 | 272 | 48 | 24 | 0 | 523 | 523 | 250 | 211.5 | 12.4 | 124 |
For a full-season fertilization program, explore NutriNet here.
Optimizing Fertilizer Application
Precision fertilization is key to maximizing crop profitability in citrus cultivation. The best results are achieved through:
- Nutrigation™ (fertigation) with water-soluble fertilizers for efficient nutrient delivery.
- Controlled-release fertilizers (CRFs) for continuous nutrient availability with soil application.
- Foliar nutrition with Haifa’s specialized fertilizers and micronutrients to enhance plant performance and prevent deficiencies during the vegetative stage.
Explore Haifa’s complete Haifa’s Citrus Crop Guide
