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.
With promising results that suggest its ability to dramatically improve water- and nutrient-use efficiency, fertigation technology is gaining in popularity across the world.
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 fertigation as they are highly soluble in water.
Fe, Mn, Zn, Cu, B, Mo are also supplied along with special fertilisers.
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
Rock Phosphate and some other mineral fertilizers containing phosphorus are insoluble in water.
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.
HOW FERTIGATION SYSTEM WORKS
Fertigation technology suggests sprinkling fertilizers into the precision irrigation system from reservoirs with water-soluble fertilizers.
Typically, it is done with injectors and a pressure-controlled valve.
Most fertigation systems are equipped with sensors to measure pH levels and electric conductivity. This way, necessary fertilizer rates can be determined on fields, and fertigation and irrigation system injectors can be set accordingly.
There are several types of fertigation systems, distinguished by their size and scale, management approach, and application strategy.
ADVANTAGES OF FERTIGATION
Harmony between nutrient supply and crop demand
Synchronization of nutrient supply and crop demand enhances nutrient-use efficiency. Fertigation is beneficial because nutrients are supplied uniformly to the root zone as they are required by the crop.
Greater crop growth and yield
Applying nutrients with water has been shown to result in greater crop growth and yield in both fruit and vegetable crops when compared to traditional soil application methods of fertilizer.
Crop yield, on average, has been shown to increase 12% compared to traditional fertilization practices. This yield increase can largely be attributed to meeting crop nutrient requirements in a timely fashion.
Greater fertilizer and water savings
Fertilizer use efficiency through fertigation ranges between 80-90 per cent, which helps to save a minimum of 25 per cent of nutrients.
Fertilizing and irrigating crops through fertigation increases water and Nitrogen use efficiency. Because nutrients are supplied through irrigation water, they are already in soluble forms available for plant uptake .
Nutrients and water are supplied near the active root zone through fertigation which results in greater absorption by the crops.
Reduced labour , time and energy
Fertigation systems are often comprised of automated controls, resulting in a reduction of labour , time and energy.
Reduced leaching and groundwater contamination
Fertigation has been shown to reduce both fertilizer input and nutrient leaching . Compared to traditional granular fertilizer systems, fertigation uses less fertilizer.
The frequent application of small quantities of nutrients is responsible for the greater nutrient-use efficiency observed in fertigation systems .
Smaller quantities of nutrients are applied to the soil. Therefore, little is available for leaching under heavy rainfall events. Less leaching potential reduces the risk of groundwater contamination.
Reduction in weeds
Weed dry weight and population numbers are shown to be greater when crops are grown with conventional fertilization and furrow irrigation as compared to drip fertigation .
DISADVANTAGES OF FERTIGATION
High initial costs
A considerable limitation in fertigation systems is the high cost associated with construction.
Initial costs for fertigation typically include the purchase of tanks, injectors, backflow prevention valves, and timers High-cost corrosion-resistant materials are recommended.
Requirement of consistent care
Any flaw in a fertigation system may lead to yield loss, inconsistent growth, and equipment damage. It is important to fully understand fertigation systems to fix and maintain the equipment.
Clogging
The most common irrigation system for fertigation is drip irrigation , a system prone to clogging . It is important to use the right fertilizer and quality irrigation water.
To prevent precipitation and clogging, water-soluble fertilizers with near-neutral pH and a low salt index are needed.
There is risk for precipitation in fertigation systems when using fertilizers with calcium or magnesium.
Alkalinity of a fertigation system
Often the fertigation system becomes alkaline.
The pH of the irrigation water is of great importance, as it affects many chemical reactions.
In fertigation, the reasons for adjusting the pH to an optimal range are:
1. To allow optimal uptake of nutrients, especially micronutrients;
2. To keep the irrigation system free from clogging.
The alkalinity of a fertigation system can be controlled by adding acid.
The injection of acid to the irrigation water should be, as much as possible, uniform and continuous, throughout the entire duration of the irrigation.
Must read: Conservation Agriculture – principles , benefits & problems
External link: https://en.wikipedia.org/wiki/Fertigation
PRACTICE QUESTIONS
QUES . What are the advantages of fertigation in agriculture? UPSC 2020
1. Controlling the alkalinity of irrigation water is possible.
2. Efficient application of Rock Phosphate and all other phosphatic fertilizers is possible.
3. Increased availability of nutrients to plants is possible.
4. Reduction in the leaching of chemical nutrients is possible.
Select the correct answer using the code given below:
(a) 1, 2 and 3 only
(b) 1, 2 and 4 only
(c) 1,3 and 4 only
(d) 2, 3 and 4 only
(c)