Published in: February 2017
Due to the current drought in Tamil Nadu, it’s becoming increasingly difficult to protect perennial crops. Coconut, a major crop grown in all districts, is particularly vulnerable to drought. Here are some methods to protect coconut trees from the effects of drought.
Vulnerability to Drought
Coconut trees are highly susceptible to drought due to their lack of deep roots and reliance on fibrous roots, which are mostly found within 60 cm of the soil surface. They cannot access deep water or store water in their bodies, making them unable to withstand prolonged dry periods.
Impact of Drought
Coconut trees are affected in areas with less than 1,000 mm of rainfall or where there is no rain for more than three months. Trees suffer when temperatures exceed 35°C and relative humidity drops below 50%.
The impact of drought on coconut trees includes:
- Wilting and yellowing of leaves.
- Shedding of coconuts and flowers.
- Severe drought can cause leaves to dry up, leading to the death of the tree.
- Economic losses for farmers due to reduced yield and quality.
Management Practices
1. Basin Formation
Create a circular basin around the coconut tree with a radius of 1.8 meters and a depth of 20 cm to retain moisture. This method helps in maintaining soil moisture around the root zone.
2. Mulching
Mulch the basin with 15-20 coconut leaves to reduce soil temperature by about 6°C and conserve moisture.
3. Burying Coconut Husk
Create a circular trench 1.8 meters from the tree, 50 cm deep and wide. Fill this trench with coconut husks, fibrous side up, and cover with soil. These husks absorb and retain moisture, providing water to the tree during drought.
4. Trench Method
Dig trenches 2 meters wide and 50 cm deep between rows of coconut trees. Fill with coconut husks, fibrous side up, and cover with 5 cm of soil. This method helps retain rainwater and provides moisture during dry periods.
5. Applying Clay Soil
Apply clay soil from dried-up ponds to the basin during summer. Mixing it with decomposed coconut waste, at a rate of 50 kg per tree, helps retain soil moisture.
6. Additional Potassium Application
Potassium helps coconut trees withstand drought by reducing water loss through leaves and improving water use efficiency. Apply 4 kg of potassium per tree annually, in two splits (July-August and December-January).
7. Balanced Fertilization
Apply 1.3 kg of urea, 2 kg of superphosphate, and 4 kg of potassium per tree annually in two splits. Ensure irrigation after fertilization during dry periods.
8. Sodium Chloride Application
Combine 2 kg of potassium with 2 kg of table salt (sodium chloride) per tree. Sodium and chlorine improve drought tolerance and the structural integrity of leaves.
9. Leaf Pruning
Reduce water loss by cutting off leaves during severe drought. Retain only the top three leaves around the growing point.
10. Use of Biofertilizers
Use Vesicular Arbuscular Mycorrhizae (VAM) biofertilizers at a rate of 1 kg per acre. VAM extends the root system, improving water and nutrient uptake.
11. Drip Irrigation
Install drip irrigation with 4-6 drippers around each tree, placed 1 meter away and 30 cm deep. Connect the drippers to a PVC pipe filled with coconut coir to deliver water directly to the roots, reducing evaporation.
Planting Drought-Resistant Varieties
Opt for drought-resistant coconut varieties like:
- West Coast Tall
- Java Giant
- PG Tall
- Malayan Tall
In Tamil Nadu, varieties like East Coast Tall, Veppankulam 3, and Aliyar 1, 3 are recommended for better drought tolerance.
By implementing these strategies, farmers can effectively protect their coconut trees from drought and ensure better yield and quality.
J. Kathiravan, Agricultural Science Centre, Hans Roever Campus, Valikandapuram, Perambalur – 621 115.
