Nutrient Management - Fertigation

By TamilNadu Agricultural University on 30 Dec 2018 | read
    06

Fertigation

Fertigation is a method of fertilizer application in which fertilizer is incorporated within the irrigation water by the drip system. In this system fertilizer solution is distributed evenly in irrigation. The availability of nutrients is very high therefore the efficiency is more. In this method liquid fertilizer as well as water soluble fertilizers are used. By this method, fertilizer use efficiency is increased from 80 to 90 per cent.

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Micro Irrigation and Fertigation

Image titleFertigation


Fertilizer efficiencies of various application methods

NutrientFertilizer use efficiency (%)
Soil applicationFertigation
Nitrogen30-5095
Phosphorous2045
Potassium5080

 Advantages of fertigation

  • Nutrients and water are supplied near the active root zone through fertigation which results in greater absorption by the crops.
  • As water and fertilizer are supplied evenly to all the crops through fertigation there is possibility for getting 25-50 per cent higher yield.
  • Fertilizer use efficiency through fertigation ranges between 80-90 per cent, which helps to save a minimum of 25 per cent of nutrients.
  • By this way, along with less amount of water and saving of fertilizer, time, labour and energy use is also reduced substantially.

Water saving, yield and profit under drip and drip fertigation systems

CropsWater Saving (%)Yield (t/ha)Profit (Rs/ha)
ConventionalDripDrip+
Fertgn
ConventionalDripDrip +
Fertgn
Banana352630378100098000120000
Sugarcane29120160207300004700068000
Tomato32455665560007700095000

Fertilizer used in fertigation

  • Urea, potash and highly water soluble fertilizers are available for applying through fertigation.
  • Application of super phosphorus through fertigation must be avoided as it makes precipitation of phosphate salts. Thus phosphoric acid is more suitable for fertigation as it is available in liquid form.
  • Special fertilisers like mono ammonium phosphate (Nitrogen and Phosphorus), poly feed (Nitrogen, Phosphorus and Potassium), Multi K (Nitrogen and Potassium), Potassium sulphate (Potassium and Sulphur) are highly suitable for fertigation0 as they are highly soluble in water.   Fe, Mn, Zn, Cu, B, Mo are also supplied along with special fertilisers.

Fertilizers commonly used in fertigation

NameN – P2O5 – K2O contentSolubility 
(g/l) at 20 C
Ammonium nitrate
Ammonium sulphate
Urea
Monoammonium phosphate
Diammonium phosphate
Potassium chloride
Potassium nitrate
Potassium sulphate
Monopotassium phosphate
Phosphoric acid
34-0-0
21-0-0
46-0-0
12-61-0
18-46-0
0-0-60
13-0-44
0-0-50
0-52-34
0-52-0
1830
760
1100
282
575
347
316
110
230
457

Specialty water soluble fertilizers

Name
N %P2O5 %K2O %
Polyfeed191919
Polyfeed202020
Polyfeed114211
Polyfeed16824
Polyfeed191919
Polyfeed151530
MAP12610
Multi-K13046
MKP05234
SOP0050

N fertigation 

Urea is well suited for injection in micro irrigation system. It is highly soluble and dissolves in non-ionic form, so that it does not react with other substances in the water. Also urea does not cause precipitation problems. Urea, ammonium nitrate, ammonium sulphate, calcium ammonium sulphate, calcium ammonium nitrate are used as nitrogenous fertilizers in drip fertigation. 

P fertigation

Application of phosphorus to irrigation water may cause precipitation of phosphate salts.  Phosphoric acid and mono ammonium phosphate appears to be more suitable for fertigation.

K fertigation

Application of K fertilizer does not cause any precipitation of salts. Potassium nitrate, Potassium chloride, Potassium sulphate and mono potassium phosphate are used in drip fertigation.

Micro nutrients 

Fe, Mn, Zn, Cu, B, Mo could be used as micro nutrients in drip fertigation.

Fertigation equipments

Three main groups of equipments used in drip system are :

  • Ventury
  • Fertilizer tank
  • Fertilizer pump

Ventury

Construction in the main water flow pipe causes a pressure difference (Vaccum) which is sufficient to suck fertilizer solution from an open container into the water flow. It is very easy to handle and it is affordable even by small farmers. This equipment is most suitable for smaller area.

Fertilizer tank

A tank containing fertilizer solution is connected to the irrigation pipe at the supply point.  Part of the irrigation water is diverted through the tank diluting the nutrient solution and returning to the main supply pipe.  The concentration of fertilizer in the tank thus becomes gradually reduced.

Fertilizer pump

The fertilizer pump is a standard component of the control head. The fertilizer solution is held in non-pressurised tank and it can be injected into the irrigation water at any desired ratio. Therefore the fertilizer availability to each plants is maintained properly.

Cost of fertigation equipments

Sl.No.
Fertigation devicesCost (Rs.)
1.Ventury type1200
2.Fertilizer Tank3000
3.Injectors12000

Economics of drip irrigation system

The initial investment in drip irrigation system is mainly depends upon the spacing of crops.  The initial cost will be almost 20-25 thousand rupees per hectare for wider spacing crops such as coconut, mango, grapes and for orchard crops. The initial cost is approximately 50-70 thousand rupees per hectare for close spacing crops such as sugarcane, banana, papaya, mulberry, turmeric, tapioca, vegetables and flower crops.Image title

 

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