Use of a mixture of biotite- and apatite-rich rock powder in a soil with inherent low soil fertility.

Long-term fertility of organically managed soils is challenged by repeated removal of plant nutrients through cash crops. The use of selected rock powders may contribute to maintain soil fertility. A pot trial with Italian ryegrass and white clover was used in order to study the potential of a biotite-rich and of an apatite-rich rock powder to maintain and improve the nutrient supply of organically managed soils.