FERTILIZER MANAGEMENT IN TEA

Need of fertilizer application

In generally 16 nutrients are essential for normal plant growth and crop production. Plants derive 3 major nutrients from air and water, and the remaining from soil. However, 3 nutrients viz., Nitrogen (N), Phosphorus (P) and Potassium (K), which are required in large amount, are not adequately available in the soil to Support the sustained production and needed to be applied through external fertilizers. It has been reported that production of 1000 kg tea-leaf (dry weight) removes 40-50 kg nitrogen, 4-8.5 kg phosphorus and 16-19 kg potash. Besides, stems and older leaves also lock about 50 kg nitrogen,12 kg phosphorus and 32 kg potash. Weeds growing in tea field absorb substantial quantity of the nutrients and if removed from the fields, result in their permanent loss. The removal of nutrients thus, has to be compensated by their external application. Besides, response of other nutrients viz., sulphur, magnesium, zinc etc. is being noticed in high productive gardens.

Role of fertilizers Nitrogen

Phosphorus

Potassium

F1
Application of fertilizers Fertilizer doses
For the tea plantations in Himachal Pradesh, the following interim recommendation is being given:

For exact recommendation of the fertilizers, the growers are advised to maintain section-wise crop yield and soil-nutrient status data.

Calculation of fertilizer dose
Dose of any fertilizer can be calculated by using following formula:
Quantity of Fertilizer required = 100 x Dose of nutrient
                                                Nutrient content  
For example, if 90 kg nitrogen per ha is to be applied through Ammonium sulphate fertilizer, containing 20.6 % nitrogen (N), the quantity of Ammonium sulphate needed would be:
Quantity of Ammonium sulphate = 100 x 90/20.6
= 437 kg say, 9 bags per ha (1bag = 50 Kg) The ready recknor given below may be used for fertilizer application:

 

Fertilizer

*For 1 ha (25 kanal)

Unpruned
Tea

Pruned
Tea

Ammonium
sulphate
alternate Year
Urea

9-12 bags

4-5 bags

9 bags

4 bags

Single Super
Phosphate

11 bags

11 bags

Muriate of Potash

 

3 bags

3-4 bags

* Dose of phosphorus and potash may be reduced if their available status in the soil is very high.

Time of application
After thorough mixing, the fertilizers should be applied before the onset of plucking season i.e. during February- March after rain when there is sufficient soil moisture. In pruned sections, the fertilizer should be applied after the first flush i.e. in June when the bushes attain sufficient foliage.

Method of application
In wide-spaced sections, where the ground coverage is not complete, apply the fertilizer mixture in a broad ring corresponding to the periphery of the bush frame. In sections where ground coverage is complete and the bushes are compact, it will be practically difficult to apply fertilizers in a ring. In such case, apply fertilizer between the rows in a broad band or broadcast it uniformly all over the ground, avoiding the dumping or heaping of the fertilizers within the bush frame or at the collar level.
            The fertilizer may be applied in a single split (March) or in two splits (March and June) as per the convenience. However, in gardens where extra dose of fertilizer is needed, it should be applied in two splits.
In case of young tea, nitrogen, phosphorus and potash fertilizers should be applied in the ratio of 3:2:4 with nitrogen dose of 20, 40, 60 and 80 kg per ha in the first, second, third and forth year of planting, respectively in the ring method.

F2

Properties of commonly used fertilizers
 (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.

F3

(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.

IMPROVING FERTIUSER USE EFFICIENCY

SOURCE OF FERTILIZERS, THEIR CONVERSION FACTOR AND UNIT COST

Fertilizer

Nutrient
content

*kg fertilizer required for
1 kg nutrient

Price of Fertilizer
(Rs/Kg)

Unit cost of nutrient
(Rs)

SoA

20.6% N

4.85

6.37

30.92

Urea

46% N

2.17

4.83

10.50

CAN

25% N

4.00

10.56

42.24

SSP

16% P2O5

6.25

3.80

23.75

MRP

20% P2O5

5.00

2.60**

13.00

MoP

60% K2O

1.67

4.46

7.43

* Conversion factor; ** Estimated