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Complex fertilizers

Complex fertilizers – fertilizers containing two or more nutrients, including microelements (micronutrients).

Classification of complex fertilizers

According to the number of components complex fertilizers are classified:

  • dual, for example, containing phosphorus-potassium, nitrogen-phosphorus, nitrogen-potassium;
  • triple, containing nitrogen, potassium and phosphorus.

According to the method of production:

  • complicated;
  • complex-mixed (combined);
  • mixed.

By aggregate state;

  • solid;
  • liquid.

Complicated fertilizers

Main article: Complicated fertilizers

Complicated fertilizers – mineral salts containing several plant nutrition elements, such as potassium nitrate (KNO3), ammonium hydrophosphate ((NH4)2NPO4). As a rule, they do not contain impurities (ballast), so they have a high content of nutrients.

Complex-mixed (combined) fertilizers

Complex-mixed (combined) fertilizers – complex fertilizers containing two or more nutritional elements, obtained in one technological process by interaction of nitric, phosphoric and sulfuric acids with ammonia, natural phosphates, potassium salts or ammonium. In terms of chemical composition they are a mixture of several mineral salts.

The main technological operations in the production of complex mixed fertilizers: mixing the initial components, ammonization of the mixture, granulation, drying and conditioning the product. As a result, you can get fertilizer grades with different ratios of nutrients. For example, on the basis of simple and double superphosphate, ammonium nitrate, ammonium sulfate, an ammoniating solution consisting of 21.7% ammonia and 65% ammonium nitrate, sulfuric acid can be obtained fertilizers of composition: 5:10:20; 5:20:20; 8:16:16; 8:24:0; 8:24:8; 8:24:16; 10:20:0; 10:20:12; 12:12:12; 5:10:10. Using a solution containing 26-30% urea, 14-24% ammonium nitrate, and 25-35% NH3, a 20:10:10; 15:15:15:15 fertilizer is made. On the basis of polyphosphoric acid using ammonia, sulfuric acid, simple and double superphosphate and potassium chloride, fertilizers are produced brands 6:24:24; 10:45:5; 8:32:16 and others with a water-soluble phosphate content of 65%.

Complex-mixed fertilizers include solurin and crystallin, containing nitrogen, phosphorus, potassium, magnesium, trace elements (Mn, Zn, Cu, Co, I, etc.). Fertilizer is soluble in water, it is used in greenhouses and in open ground. Solurin grades 10:5:20:6; 18:6:18:0; 19:6:6:6:0; 13:40:13:0; 17:17:6:0; 16:16:16:0; 20:16:20.

Mixed fertilizers

Main article: Mixed fertilizers

Mixed fertilizers – complex fertilizers, obtained by mechanical mixing of two or more simple fertilizers in granular or powder form.

Liquid complex fertilizers

Main article: Liquid complex fertilizers

Liquid and suspended complex fertilizers – complex fertilizers, obtained by mixing a solution of fertilizers. Sometimes gaseous and solid substances and suspending additives are added.

Application of complex fertilizers

The advantages of complex fertilizers are the high content of nutrients with simultaneous content of several elements. The production cost of complex fertilizers (in terms of nutrients per unit) is higher than that of simple fertilizers, but the cost of delivery, storage and application is much lower compared to simple fertilizers. The total cost of application of complex fertilizers, taking into account production costs, is about 10% lower than that of simple fertilizers.

The content of a single granule of several nutrients contributes to a more uniform distribution on the soil surface.

Complex fertilizers provide better positional availability of nutrients to the root system. According to experiments, when fed separately with nitrogen, phosphorus and potassium (when placing them in different parts of the vessel), corn developed worse, absorbing less phosphorus than when fed jointly with nitrogen and potassium.

The effectiveness of equal doses of complex and a mixture of unilateral fertilizers on the effect on the yield is the same.

Depending on crops, soils, climatic conditions require complex fertilizers with different ratios and contents of nitrogen, phosphorus and potassium. They are characterized by the mass ratio of N:P2O5 : K2O, for example, 1:1,5:0,5 (nitrogen is taken as one), or the percentage ratio of N : P2O5 : K2O for the content of active elements, for example, 12:18:6 or 12-18-6, the sum of the percentage gives the total content of active substances in fertilizer.

The most common are three-component fertilizer grades 1:1:1:1; 1:1.5:1; 1:1:1.5; 1:1.5:1.5; 1:1:0.5 and two-component grades 1:2.5:0; 1:4:0; 1:1:0; 0:1:1:1; 0:1:1.5.

The ratio between the components in the composition of fertilizers does not always correspond to the needs of crops when growing on soils with different security, so in such cases, in addition one-sided fertilizers or appropriate fertilizer mixtures are made.


Yagodin B.A., Zhukov Y.P., Kobzarenko V.I. Agrochemistry/Under ed. B.A. Yagodin. – M.: Kolos, 2002. – 584 p.: ill.

Agrochemistry. Textbook / V.G. Mineev, V.G. Sychev, G.P. Gamzikov et al. – M.: Publishing house of the All-Russian Scientific Research Institute named after D.N. Pryanishnikov, 2017. – 854 с.