Impact of coal ash and phosphogypsum application on soil fertility of Chernozem soils of North Kazakhstan

Industrial waste stocks in Kazakhstan significantly increase and only 10-15 % of total generated industrial waste is utilized. Industrial waste dumps occupy large areas, have negative impact on the environment and degradation of landscape. Sustainable waste management strategy leads to waste recycling and development of new waste recycling technologies. The coal ash and phosphogypsum usage as soil fertilizers is appropriate, however, there is a need for additional investigation of ecological risks related with this industrial waste utilization technology. The aim of this research is to investigate the effect of phosphogypsum and coal ash application on North Kazakhstan chernozem soils in production conditions. There was phosphogypsum and coal ash application influence tested on the soil fertility, food safety and crop yield. Three experimental fields, with the area of 10 ha each, were developed and investigated since 2014. For coal ashes (200 kg·ha -1 ), phosphogypsum (1 t·ha -1 ) and control experimental fields different fertilization plans were defined. The soil samples were collected three times a year and the initial content of humus, рН, plant nutrient elements and heavy metal content of the soil were tested in laboratory. The experiment results in general show positive effect on soil fertility and crop yield. The wheat yield was significantly higher in coal ash (30.0 c·ha -1 ) and phosphogypsum (24.0 c·ha -1 ) fields comparing with the control field (15.9 c·ha -1 ). Nitrogen was in the some level (38.837.6 mg·kg -1 ) in all three experimental fields, however, potassium was higher in the coal ash field. The results in pH show the neutralization process in soil environment. There is still a need for additional research to be done in case of heavy metal accumulation and the impact on food safety.