While travelling through Champagne region, it was often said that the top soil in the vineyards seem to be glittering. On a closer look it was found to be crushed glass, part of a larger trash. All that glitters is not gold, after all !!
Surprisingly, this was because of the practice where-in sterilized trash (boues google translates to sludge) from Paris or Reims used to be spread in the champagne vineyards – to break up clay soils and control erosion. While it was originally organic, it eventually grew to include bits of plastic, glass, and metal that posed environmental threats.
So, after being extensively used from 1960s this practise was ultimately discontinued in 1998.
(Ref – Peter Liem/internet)