Nutrient Composition and Chemical Matrix
NPK 13:40:13 is a balanced, high-analysis water-soluble complex fertilizer containing 13% total Nitrogen, 40% water-soluble Phosphate (P2O5), and 13% water-soluble Potash (K2O).
Formulated from high-purity monoammonium phosphate (MAP), potassium nitrate, and urea, it provides rapid nutrient availability through drip fertigation lines without leaving insoluble residue.
- Nitrogen (N): 13 percent (balanced ammoniacal and nitrate forms for steady vegetative uptake)
- Phosphate (P2O5): 40 percent (100% water-soluble orthophosphate for rapid root energy)
- Potash (K2O): 13 percent (water-soluble potassium for cellular turgor and enzyme activation)
- Regulatory standard: Formulated and certified under Schedule I of the Fertilizer (Control) Order (FCO)
Physiological Roles and Stage-Specific Applications
The prominent phosphate content in 13:40:13 supplies adenylate energy (ATP and ADP) critical for cellular division and rapid primary and secondary root branching during seedling establishment.
Applying 13:40:13 during the floral transition phase accelerates flower bud differentiation, improves pollen grain fertility, and minimizes premature flower drop across high-value horticulture and vegetable crops.
- Root establishment: Drives deep taproot elongation and dense lateral feeder root formation
- Floral initiation: Supplies phosphorus and potassium required for flower bud development
- Transplant recovery: Eliminates transplanting shock in nursery seedlings and greenhouse crops
- Target crops: Tomato, chilli, capsicum, pomegranate, grapes, cotton, and open-field vegetables
Drip Fertigation and Foliar Spray Guidelines
NPK 13:40:13 dissolves completely in water, producing a low-salinity, slightly acidic spray solution that enhances foliar stomatal absorption.
For foliar spraying, dissolve 5 grams per liter of water (0.5% concentration). For drip irrigation systems, inject through venturi or fertilizer tanks at 3 to 5 kg per acre per application during early growth stages.
- Foliar concentration: 4 to 5 g per liter of clean water sprayed during early morning hours
- Drip fertigation rate: 3 to 5 kg per acre per fertigation round during vegetative and pre-bloom stages
- Solubility: 100 percent water-soluble leaving zero precipitate in drip drippers or micro-jets
- Tank compatibility: Fully compatible with neutral micronutrients; avoid mixing with concentrated calcium fertilizers
Official source
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Department of Fertilizers, Ministry of Chemicals and Fertilizers ↗Related on KisanPe
Common questions
What is the primary benefit of applying NPK 13:40:13 over standard 19:19:19?
NPK 13:40:13 contains more than double the phosphorus concentration (40% P2O5), making it superior for rapid root establishment and floral bud induction compared to balanced 19:19:19.
Can NPK 13:40:13 be mixed with Calcium Nitrate in the same fertilizer tank?
No, concentrated soluble phosphates react with calcium to form insoluble calcium phosphate precipitate, which can clog drip emitters; apply them through separate fertilizer tanks.
At what crop growth stage should NPK 13:40:13 be applied?
It is best applied during two critical stages: during early seedling establishment (for root development) and right before flowering (for bud initiation).
General guidance, not personal advice. For your farm, ask your local Krishi Vigyan Kendra or agriculture officer.
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