Jackfruit Fertilizer Recommendations

Nutrient Requirements for Jackfruit

Jackfruit trees primarily need Nitrogen (N), Phosphorus (P), and Potassium (K) for their main growth functions. Nitrogen promotes vegetative growth and leaf development. Phosphorus is vital for root development, flowering, and fruit setting. Potassium is crucial for fruit quality, disease resistance, and overall plant health. Besides these macronutrients, micronutrients like Zinc, Boron, Manganese, and Iron are also needed in smaller quantities.

• Nitrogen (N): For leaf and shoot growth.

• Phosphorus (P): For root development, flowering, and fruit set.

• Potassium (K): For fruit size, quality, and disease resistance.

• Micronutrients: Zinc, Boron, Manganese, Iron are important for various metabolic functions.

Fertilization Schedule for Young Trees (Non-Bearing)

For young jackfruit trees (1-3 years old) that are not yet bearing fruit, the focus is on establishing a strong root system and vigorous vegetative growth. Fertilizers should be applied in split doses to ensure continuous nutrient availability and prevent leaching.

Tree Age (Years) Nitrogen (N) per tree per year (g) Phosphorus (P2O5) per tree per year (g) Potassium (K2O) per tree per year (g) 1 50-100 25-50 50-100 2 100-200 50-100 100-200 3 200-300 100-150 200-300

These annual doses should be divided into 2-3 applications, typically in June-July (monsoon onset) and September-October (post-monsoon). For very young trees, a small amount of well-rotted farmyard manure (FYM) or compost (5-10 kg) can also be mixed into the soil around the base.

Fertilization Schedule for Bearing Trees

Once jackfruit trees start bearing fruit (typically from 4-5 years onwards), their nutrient requirements increase significantly to support fruit development. The fertilizer dose should be gradually increased as the tree matures and its yield potential grows.

Tree Age (Years) Nitrogen (N) per tree per year (g) Phosphorus (P2O5) per tree per year (g) Potassium (K2O) per tree per year (g) FYM/Compost per tree per year (kg) 4-6 300-500 150-250 300-500 20-30 7-10 500-750 250-375 500-750 30-40 10+ (Mature) 750-1000 375-500 750-1000 50-100

For bearing trees, it's recommended to apply fertilizers in two main splits:

1. First application (Pre-monsoon, May-June): Apply half of the annual N, full P, and half K. This supports flowering and initial fruit set.

2. Second application (Post-monsoon, September-October): Apply the remaining half of N and half K. This helps in fruit development and promotes new flush growth for the next season.

Farmyard manure or compost should be applied once a year, preferably during the pre-monsoon period, mixed into the soil around the tree basin.

Application Methods and Best Practices

Correct application ensures nutrients are available to the tree roots and minimizes waste.

• Soil Testing: It is highly recommended to conduct a soil test every 2-3 years. This provides precise information about your soil's nutrient status and pH, allowing for more accurate fertilizer adjustments.

• Application Zone: Fertilizers should be applied in a circular trench or band around the tree, starting about 1-1.5 meters from the trunk and extending to the drip line (the edge of the canopy). For mature trees, this zone can be wider.

• Mixing and Watering: After broadcasting the fertilizer, lightly incorporate it into the topsoil (5-10 cm deep) and then water thoroughly. This helps dissolve the nutrients and move them into the root zone.

• Micronutrients: If soil tests indicate deficiencies, micronutrients can be applied as foliar sprays or soil applications. Zinc sulfate (0.5%) and Borax (0.1-0.2%) are common for jackfruit.

• Organic Matter: Regular application of farmyard manure, compost, or vermicompost improves soil structure, water retention, and nutrient availability, reducing the need for chemical fertilizers over time.

Signs of Nutrient Deficiency

Observing your trees for signs of nutrient deficiency can help you adjust your fertilization program.

• Nitrogen Deficiency: Yellowing of older leaves, stunted growth, pale green foliage.

• Phosphorus Deficiency: Dull, bronze, or purplish discoloration of leaves, poor flowering and fruiting.

• Potassium Deficiency: Yellowing and browning (scorching) along the leaf margins, especially on older leaves, poor fruit development.

• Zinc Deficiency: Small, narrow leaves (little leaf), yellowing between veins (interveinal chlorosis) on new growth.

• Boron Deficiency: Cracking of fruits, internal browning, distorted new growth.

By following these fertilizer recommendations and regularly observing your jackfruit trees, you can ensure their robust health and achieve bountiful harvests. Remember that soil testing is the best way to fine-tune your fertilization program for specific local conditions.