Fertigation is the application of fertilizers, soil amendments, or other water

Water

Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

-soluble products through an irrigation

Irrigation

Irrigation may be defined as the science of artificial application of water to the land or soil. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall...

 system.

Chemigation, a related and sometimes interchangeable term, is the application of chemicals through an irrigation system. Chemigation is considered to be a more restrictive and controlled process, due to the potential nature of the products being delivered - pesticide

Pesticide

Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...

s, herbicide

Herbicide

Herbicides, also commonly known as weedkillers, are pesticides used to kill unwanted plants. Selective herbicides kill specific targets while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often synthetic "imitations" of plant...

s, fungicide

Fungicide

Fungicides are chemical compounds or biological organisms used to kill or inhibit fungi or fungal spores. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality and profit. Fungicides are used both in agriculture and to fight fungal infections in animals...

s - to cause harm to humans, animals, and the environment. Therefore, chemigation is in general more regulated than fertigation.

Usage

Fertigation is used extensively in commercial agriculture and horticulture and is starting to be used in general landscape applications as dispenser units become more reliable and easy to use.

• Fertigation is used to spoon-feed additional nutrients or correct nutrient deficiencies detected in plant tissue analysis

• Usually practiced with high-value crops such as vegetables, turf, fruit trees, and ornamentals

• Injection during middle one-third or the middle one-half of the irrigation recommended for fertigation using micropropagation

• Water supply for fertigation kept separate from domestic water supply to avoid contamination

• Change of fertilizer program during the growing season in order to adjust for fruit, flower, and root development.

Commonly used nutrients

• most plant nutrients can be applied through irrigation systems

• Nitrogen
  Nitrogen
  Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
  
   is most commonly used nutrient

• Other nutrients include nitrate
  Nitrate
  The nitrate ion is a polyatomic ion with the molecular formula NO and a molecular mass of 62.0049 g/mol. It is the conjugate base of nitric acid, consisting of one central nitrogen atom surrounded by three identically-bonded oxygen atoms in a trigonal planar arrangement. The nitrate ion carries a...
  
  , ammonium
  Ammonium
  The ammonium cation is a positively charged polyatomic cation with the chemical formula NH. It is formed by the protonation of ammonia...
  
  , urea
  Urea
  Urea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group....
  
  , phosphate
  Phosphate
  A phosphate, an inorganic chemical, is a salt of phosphoric acid. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry and biogeochemistry or ecology. Inorganic phosphates are mined to obtain phosphorus for use in...
  
  , and potassium
  Potassium
  Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...
  
  .

Determining which nutrient is used

• A soil fertility analysis is used to determine which of the more stable nutrients should be used

Advantages

Benefits of fertigation over traditional broadcast or drop-fertilizing methods include:

• Increased nutrient absorption by plants
• Reduction in fertilizer and chemicals needed
• Reduced leaching to the water table
• Reduction in water usage due to the plant's resulting increased root mass's ability to trap and hold water
• Application of nutrients at the precise time they are needed and at the rate they are utilized

Disadvantages

• Concentration of solution decreases as fertilizer dissolves, leading to poor nutrient placement

• Results in pressure loss in main irrigation line

• Limited capacity

• Use of chemical fertilizers of low-sustainability
  Sustainability
  Sustainability is the capacity to endure. For humans, sustainability is the long-term maintenance of well being, which has environmental, economic, and social dimensions, and encompasses the concept of union, an interdependent relationship and mutual responsible position with all living and non...
  
  , instead of organic fertilizer
  Organic fertilizer
  Organic fertilizers are naturally occurring fertilizers .Naturally occurring organic fertilizers include manure, slurry, worm castings, peat, seaweed, humic acid, and guano. Sewage sludge use in organic agricultural operations in the U.S...
  
  s.

• Dependent on water supply's nonrestriction by drought
  Drought
  A drought is an extended period of months or years when a region notes a deficiency in its water supply. Generally, this occurs when a region receives consistently below average precipitation. It can have a substantial impact on the ecosystem and agriculture of the affected region...
  
   rationing.

Controls

Because of the potential risk in contaminating the potable (drinking) water supply, a backflow prevention device

Backflow prevention device

A backflow prevention assembly is used to protect water supplies from contamination or pollution.In water supply systems, water is normally maintained at a significant pressure to enable water to flow from the tap, shower etc...

is required for most fertigation systems. Backflow requirements vary greatly, so it is very important to understand the proper level of backflow prevention required by law. In the United States, the minimum backflow protection is usually determined by state regulation, but each city or town may increase the level of protection required.

Methods used in fertigation

• Drip irrigation, which reduces per water and nutrient application rates relative to sprinklers

• Sprinkler systems, which increase leaf and fruit quality.

• Other methods of application include lateral move, traveler gun, and solid set systems

• Continuous application - fertilizer is supplied at a constant rate
• Three-stage application - irrigation starts without fertilizers and then the later in process fertilizers are applied

• Proportional application - injection rate is proportional to water discharge rate

• Quantitative application - nutrient solution is applied in a calculated amount to each irrigation block

All systems should be placed on a raised and/or sealed platform, not in direct contact with the earth, and fitted with chemical spill trays.

In order to determine the injection rate for the particular fertilizer being used, one should use the formula:

Maximum injection rate = (5 x Q x L) / (f X 60)

where Q = irrigation pump discharge in liters per second, L = fertilizer tank volume in liters, and F = amount of fertilizer in grams.

System design

Fertigation assists distribution of fertilizers for farmers. The simplest type of fertigation system consists of a tank with a pump, distribution pipes, capillaries, and dripper pen.

What should be considered

• Water quality

• Soil type

• Nutrient consumption (daily)

• Appropriate nutrient materials

Possible strategies to be used

• Injecting for short time-periods at the beginning, middle, and end of irrigation cycle

• Injecting during middle 50% of the irrigation cycle

• Continuous irrigation

• Postering index Imex