Abstract
Degradation, reduction of soil fertility, and accumulation of industrial waste is both global and national environmental problem. The purpose of the study is to evaluate the effectiveness and environmental safety of the use of fertilizers made from ash and slag on ordinary chernozem for common flax (Linum usitatissimum) crops. The laboratory experiments were conducted in the environmental protection laboratory. The field experiments were conducted at the experimental field of Kokshetau University named after Sh. Ualikhanov in the period from 2018-2020. The content of heavy metals was determined by inversion voltammetry. It was found that the fertilizer made from ash and slag contributed to the improvement of edaphic factors. On average, over 3 years, the content of agronomically valuable aggregates increased to 65.9-73.2% (56.7% in the control variant) and the water resistance of soil aggregates increased by 7-29% compared to the control variant. The ecotoxicological assessment showed that the application of fertilizers in doses of 100-500 kg/ha on ordinary chernozem did not significantly affect the content of heavy metals in the soil compared to the control variant and also did not exceed the maximum permissible and approximately permissible concentrations. On fertilized variants, the increase in the yield of common flax grain averaged 0.09-0.34 t/ha, depending on the dose of application. The greatest increase in yield was obtained in the variant "background +300 kg/ha of fertilizer", which was 51.5% higher than in the control variant. In fertilized variants, a net income of $341.2 was received, which exceeded the control variant by $125/ha; thus the profitability was 257%. Studies have shown that the introduction of fertilizer from ash and slag into the soil in doses of 100-500 kg/ha is environmentally safe.