White clovers are a top choice for "living mulch" systems planted between rows of irrigated vegetables, fruit bushes, or trees.  They are persistent, widley adapted perennial nitrogen producers with tough stems and a dense shallow root mass that protects soil from erosion and suppresses weeds.  Depending on the type, plants grow just 6-12 inches tall, but thrive when mowed or grazed.  Once established, they stand up well to heavy field traffic and thrive under cool, moist conditions and shade.  A healthy stand of white clover can produce 80 to 130 lb. N/A when killed the year after established.  In established stands, it also may provide some N to growing crops when it is managed as a living mulch between crop rows.  This is because it contains more of its total N in its roots than other legumes.  The low C:N ratio of stems and leaves causes them to decompose rapidly to release N.