Carbon-rich lime slag as a lime source in agriculture - effects on germination, plant growth and elemental content

The use of decarbonized virgin lime is connected to environmental problems like high CO2 emissions, high energy utilization and negative impact from open-pit lime mines. Recycling of used lime would reduce many of these problems. The effect of carbon-rich lime slag (CLS) from the metallurgical industry on germination, growth, and elemental content in barley, oilseed radish and sugar beet was investigated on two soils (clay and sand). CLS without and with water (CLSW) were compared to limestone in the sandy soil, primarily used to increase pH, and hydrated lime, primarily used to increase aggregation, in clay soils. CLS addition did not reduce the germination of the seeds as compared to the control. Including fertilization to the CLS treatment reduced the germination up to 23% in oilseed radish after 16 days. The germination of sugar beet seeds was delayed but had recovered after 16 days. Shoot biomass was higher in plants with CLS and CLSW, in both soils without fertilization. Plants grown in the CLS had lower Cd content compared to plants grown with hydrated lime. We can conclude that CLS show a high potential to be used on agricultural land from a crop growth perspective.