To my knowledge no specific data is available of acceptance limit of Lanthanum in soil.

However, you can find some references regarding La toxicity to soil organisms with exposure in soil on plants -

Article Lanthanum toxicity to five different species of soil inverte...

La toxicity on microorganisms-

Article Availability and toxicity of exogenous lanthanum in a haplic acrisols

Thanks.

thank you

It depends on soil types and status of soil. To my knowledge it is between 6.6 and 50 mg La per Kg of dry soil.

J. C. Tarafdar thank you sir

There some information aboput the lanthanides in Trace Elements in Soils and Plants by Kabata-Pendias. I hope the enclosed table is useful enough for you.

Veli Uygur thank you sir