资料来源 : Webster's Revised Unabridged Dictionary (1913)

Cover crop \Cov"er crop\
   A catch crop planted, esp. in orchards. as a protection to
   the soil in winter, as well as for the benefit of the soil
   when plowed under in spring.

资料来源 : WordNet®

cover crop
     n : crop planted to prevent soil erosion and provide green
         manure