Slowly soluble phosphate glasses are a promising material for new environmentally safe fertilizers. The kinetics of the dissolution of phosphate glasses used for the development of fertilizers was studied.Modern nature management is impossible without application of mineral elements, because ions of potassium, magnesium, calcium, phosphorus, boron, and trace elements are irrevocably withdrawn from soil together with agricultural products. Existing mineral fertilizers have a number of principal drawbacks connected with their crystal structure and constant composition. These fertilizers are easily washed away and weathered from the soil, which gives rise to extreme workloads on soil microorganisms and root systems of plants. Annual world production and application of fertilizers reaching 400 million tons is not only prodigal, but also environmentally dangerous, as no less than 50% of fertilizers goes to subsoil waters and is weathered, causing environmental pollution.The cardinal way of overcoming these drawbacks is to abandon traditional crystalline fertilizers and to develop essentially new highly effective fertilizers based on glassy amorphous materials. Glass is one of the most promising among these materials because of its favorable physical and chemical properties and feasibility of processing.In the early 1980s, phosphate glasses were used to develop a new generation of fertilizers [1]. These fertilizers of the prolonged action are based on glassy potassium, magnesium, and calcium metaphosphates doped with microelements. Their preparation was based on long-term experience in the field of development of optical glasses and ion-exchange processes.As a result of these studies [1, 2], a new type of glassy fertilizers (AVA) was developed; their high efficiency and environmental cleanliness are due to the high-temperature synthesis of phosphate systems, quenching of the structural state of the components in the form assimilable by plants, and their variable composition providing easy adaptation to regions of use, to types of soils, and to the kind of crops.The rate of dissolution of such glasses depends on their chemical composition. Glass components, K, Ca, and P oxides, are nontoxic. Such glasses provide egress of the required compounds from the glass into the environment. The dissolution of a glass in water is accompanied by a chemical reaction between the glass and water, which results in cleavage of the >P3O3P< bonds and passing of phosphate ions into solution. Metal ions contained in the glass together with P 2 O 5 pass simultaneously into the solution at a rate determined by the rate of the glass dissolution. The soluble phosphate glass can be used for delivering fertilizers with a specified intensity and substances for protection of plants.According to published data [3,4], the dissolution of phosphate glasses involves several steps: selective passing into a solution (leaching) of cations within the framework of internal diffusion and hydrolytic degradation of the anionic skeleton. However, the most import...
