Complex fertilizers are divided into double fertilizers (nitrogen-phosphorus, nitrogen-potassium) and triple (nitrogen-phosphorus-potassium) fertilizers. By the method of production, they are divided into complex, complex mixed, or combined, and mixed fertilizers.
Complex fertilizers contain two or three nutrients in a single chemical compound. The term "complex fertilizers" is used to refer to all complex solid and liquid mineral fertilizers in which all particles, crystals or granules have approximately the same chemical composition.
Combined, or complex mixed, include complex fertilizers, which are obtained in one technological process and contain in one granule two or three basic elements of plant nutrition. These include nitroammophos, ammonium and potassium polyphosphates, phosphate-potassium pressed fertilizers, liquid complex fertilizers, nitrophos and nitrophos, and carboammophos. For complex and complex mixed fertilizers, a high concentration of basic nutrients is characteristic.
The agronomic efficiency of equal doses of nutrients in the composition of complex and a mixture of unilateral fertilizers is almost identical with some advantage of complex ones due to the uniform distribution of nutrients in the soil and their better availability to the root system of the plant. The costs of preparation and application of unilateral fertilizers for their separate application are 2 times higher than in complex ones. Often there is a need to supplement the application of complex fertilizers by introducing one-way or using fertilizer. Mixed fertilizers are mixtures of simple and complex fertilizers that are produced in the factory or on fertilizer plants at fertilizer application sites.