football field vs soccer football

football field

noun
  • A playing field on which the game of Association football is played. 

  • An informal unit of measure of area, equal to the area of an American football field (57,600 square feet or 1.32 acres). 

  • A playing field on which the game of American football is played. 

soccer football

noun
  • Synonym of association football 

  • Synonym of soccer ball 

How often have the words football field and soccer football occurred in a corpus of books? (source: Google Ngram Viewer )