Nutrient composition and physiological functions
The distinct high-phosphorus ratio fuels energetic biochemical processes within the plant.
Nutrient roles:
- Nitrogen (13% N): Provides balanced vegetative nourishment without triggering excessive leafy canopy growth.
- Phosphorus (40% P2O5): High concentration stimulates deep lateral root elongation, strong crown formation, and abundant flower bud differentiation.
- Potassium (13% K2O): Enhances cellular turgor, disease resistance, and prepares plants for successful fruit and grain set.
- Purity: Completely water-soluble with low electrical conductivity (EC), free from harmful sodium and chloride salts.
Recommended application stages and target crops
Apply 13-40-13 during crop developmental phases when phosphorus demand peaks.
Strategic application windows:
- Early vegetative and root establishment: Applied 15 to 25 days after transplanting in vegetables (tomato, chilli, brinjal) to promote deep root systems.
- Pre-flowering stage: Applied prior to blooming in fruit crops (grapes, pomegranate, citrus) to ensure uniform floral bud emergence.
- Field crops: Applied via foliar spray in cotton during square formation and in pulses during branch tillering.
- Dilution: Typically applied at 5 to 7 grams per litre of water for foliar spraying, or 2 to 3 kg per acre per drip fertigation cycle.
Fertigation compatibility and soil testing
13-40-13 can be tank-mixed with most water-soluble fertilizers, but should not be combined with calcium-rich fertilizers (like calcium nitrate) in the same stock solution to prevent insoluble calcium phosphate precipitation. Base application quantities on recommendations from your Soil Health Card.
Official source
Check the latest rules, benefits and forms here. KisanPe is an independent platform and is not a government website.
Department of Fertilizers, Ministry of Chemicals & Fertilizers ↗Related on KisanPe
Common questions
What is the primary role of 13-40-13 water-soluble fertilizer?
Its high phosphorus content (40%) primarily promotes extensive root elongation, vigorous tillering, and prolific flower bud initiation.
Can 13-40-13 be mixed with calcium nitrate in the fertigation tank?
No, mixing soluble phosphates with calcium causes chemical precipitation of insoluble calcium phosphate, clogging drip drippers.
At what crop stage is 13-40-13 most beneficial?
It is most beneficial during the early root development phase and just before flower initiation across vegetable and fruit crops.
General guidance, not personal advice. For your farm, ask your local Krishi Vigyan Kendra or agriculture officer.
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