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Agrochemistry

Fertilizer application technology by fertigation during irrigation

For students

3 min read

AGROCHEMISTRY A

Fertilizer application with irrigation water (fertigation) during sprinkling allows for the prompt and highly accurate supply of nutrients to plants. Sprinkler machines distribute fertilizers simultaneously with irrigation during the most important growth stages of the crops. The combined effect of irrigation and nutrition provides a powerful synergistic effect, significantly increasing field productivity.

  • Yield increase compared to control — 100–110%
  • Amide nitrogen content in urea — 46%
  • Composition of liquid complex fertilizers (nitrogen and phosphorus) — 10–34–0

The efficiency of top dressing directly depends on the uniformity of the solution distribution over the irrigated area. To avoid patchiness in crops and ensure high-quality application, it is necessary to consider the following parameters:

  • wind speed and direction;
  • rotation speed of sprinkler heads;
  • hydraulic pressure in the system;
  • dosage uniformity of the stock solution into the irrigation flow.

Dosing units are used for operation, which ensure a constant flow rate of the solution and deliver it in proportion to the volume of irrigation water. This allows for maintaining a stable concentration of nutrients across the entire irrigated area. The correct selection of dosing equipment guarantees irrigation without the formation of puddles and runoff.

Monitor the correspondence between the rain intensity and the soil permeability. If the solution does not have time to be absorbed, it runs off into lower-lying areas. As a result, lowlands become waterlogged, nutrient deficiencies occur on micro-elevations, and the runoff water pollutes the environment.

Selection of fertilizer forms and rules for their dissolution

The fertilizers used must be completely soluble in water and must not form sludge that clogs nozzles. It is also important to control the chemical aggressiveness of the solutions so as not to damage the components of the sprinkler machines. Provided these requirements are met, all types of macro- and micronutrient fertilizers can be applied with irrigation water.

UAN (urea-ammonium nitrate), urea, and ammonium nitrate are suitable nitrogen fertilizers for fertigation. Solid urea is most preferred, as it is perfectly absorbed and has a neutral aqueous solution reaction. Due to this property, it can be used in higher concentrations.

Crop Permissible urea concentration in solution, %
Bean, cucumber 0.3–0.4
Tomato, corn 0.4–0.6
Tobacco 0.3–1.2
Apple, cherry, plum 0.6–1.0
Cabbage, potato 0.8–1.6
Carrot 1.2–1.3
Onion 1.6–2.5
Table beet 1.5–2.0
Cereals 5–10
Alfalfa, sugar beet 1.4–2.4

Among phosphorus fertilizers, the optimal choice is ammophos as part of a two-component nitrogen-phosphorus solution with the addition of urea. Good results are obtained with liquid complex fertilizers (LCF) of grade 10–34–0, containing 10% ammoniacal nitrogen and 34% phosphorus. It is undesirable to use double superphosphate due to the formation of coarse sludge. Potash top dressing is carried out with potassium sulfate or potassium chloride, which dissolve almost without residue.

Do not use ammonia solution for fertigation due to its high toxicity and large nitrogen losses in the form of gas. It is also prohibited to apply only potassium chloride, as its pure solution causes corrosion of the metal parts of sprinkler machines.

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