decare vs square rod

decare

noun
  • A unit of surface area equal to 10 ares (that is, 1,000 square metres, 0.10 hectares, or approximately 0.25 acres) 

square rod

noun
  • a unit of area used for measuring small quantities of land. Equal in size to a square with sides 1 rod in length. Equal to 30¼ square yards or 1/160 acre. 

  • Used other than figuratively or idiomatically: see square, rod. 

How often have the words decare and square rod occurred in a corpus of books? (source: Google Ngram Viewer )