Properties of commonly used fertilizers in Tea

 (a) Nitrogenous fertilizer

Ammonium sulphate (SoA): Most widely used fertilizer in tea, increases soil acidity, is less hygroscopic and has greater chemical stability; white to yellowish grey in Color and contains 20.6 % nitrogen and 24% sulphur.

Urea: Most concentrated nitrogenous fertilizer containing 46% N; white crystalline fairly hygroscopic, and soluble in water; partially lost by volatilization if applied on dry soil. It is also more suitable for foliar application than other nitrogen fertilizers as it causes less scorching.

b) Phosphatic fertilizers

Single super phosphate (SSP): Most commonly used phosphatic fertilizer containing 16% phosphate and 12% sulphur and 20% calcium; ash colored, available in powder and granular forms.

Rock phosphate: Contains 18-25 % phosphate, insoluble in water but soluble in acidic soil solution; required to be placed at 15-25 cm depth in soil.
Mussoori rock phosphate (MRP) - the black powder containing 18-20% phosphate - is considered better than others.

(c) Potassic fertilizers

Muriate of potash (MoP): Cheaper source and most commonly used potassic fertilizer containing 60% potash and is reddish or dull white crystalline material.

Sulphate of potash: Dirty white powdery material containing 50% potash.

(d) Mixed fertilizers

The fertilizers containing more than one nutrients are called mixed fertilizers, e.g. IFFCO mixture (12: 32: 16) contains 12% N. 32% P and 16% K. In case such mixed fertilizer are to be used, calculate its dose based on highest content of the nutrient (e.g. 32% P2O5 in case of IFFCO mixture) and calculate the outstanding balance of the remaining two nutrients which has to be compensated through their other sources. Then recalculates the required dose of these fertilizers.