This seems off by orders of magnitude. From data (Mycorrhizal Functioning: An Integrative Plant-Fungal Process; Michael Allen) an estimate of 200cm per gram of

This seems off by orders of magnitude. From data (Mycorrhizal Functioning: An Integrative Plant-Fungal Process; Michael Allen) an estimate of 200cm per gram of soil is mentioned. This would translate to 2000m per kilogram and 2.000.000m = 2000km per tonne of soil. A cubic meter of soil should weight on average 2.6g/mL so it would come out even higher at 5200 km per cubic meter. Just nitpicking :)