Concept of use of comprehensive fertilizers of long-term action on the basis of waste processing of potassium-magnesium ore as a new paradigm in improving soil fertility

Technology for the production and use of new multiple slow-release fertilizers from clay-salt waste (sludge) remaining as a result of potassium fertilizers production from natural K-Mg ores, is elaborated in Perm Federal Research Center. The main processes in the technology are waste enrichment and subsequent high-temperature calcination of the enriched concentrate. As a result, the product, received the name the calcine of clay-salt sludge, was formed having the properties of multiple slow-release fertilizer and ameliorant. Laboratory and field experiments on the calcine use as a potassium fertilizer were fulfilled. The studied crops were spring wheat, barley, and potato. The experimental scheme included such treatments: control (without fertilizers), NP - background; NP + KCl and NP + calcine. The use of calcine for grain crops (wheat, barley) on the NP background promoted the yield gains by 1.7-1.9 t/ha compared with the control, the use of standard NPK fertilizers - by 1...