By Guy Faulconbridge LONDON (Reuters) -The war in Ukraine is a tragedy that must be stopped or there will be a global food crisis, as fertiliser prices worldwide are already too high for many farmers, Russia’s coal and fertiliser king Andrei Melnichenko said on Monday. Several of Russia’s richest businessmen have publicly called for peace since President Vladimir Putin ordered the invasion on Feb 24, including Mikhail Fridman, Pyotr Aven and Oleg Deripaska. The United States and its European allies cast Putin’s invasion as an imperial-style land grab that has so far been poorly executed becaus…