Plant root systems improve the topsoil by bringing up nutrients from the
subsoil.Soil improvement—Sow thistle (Sonchus oleraceus)
brings up nutrients from the subsoil to enrich a depleted
topsoil. After years of dead sow thistle bodies enrich the
topsoil, heavier-feeding grasses return. This is part of
Nature’s recycling program, in which leached-out
nutrients are returned to the topsoil, and it is a natural
method for raising new nutrients to the upper layers of
the soil. It has been estimated that 1 cereal rye plant
grown in good soil produces an average of 3 miles of
roots per day; that is 387 miles of roots and 6,603 miles
of root hairs during a season. Plants are continuously
providing their own composting program underground.
In 1 year, plants put 800 to 1,500 pounds of roots per
acre into the soil in a small garden, and red clover puts
1,200 to 3,850 pounds of roots into the soil in the same
period of time.^2