Oppau explosion
The Oppau explosion occurred on September 21, 1921, when approximately 4,500 tonnes of a mixture of ammonium sulfate and ammonium nitrate fertilizer stored in a tower silo exploded at a BASF plant in Oppau, now part of Ludwigshafen, Germany, killing at least 560 people and injuring about 2,000 more. == Background == The plant began producing ammonium sulfate in 1911, but during World War I when Germany was unable to obtain the necessary sulfur, it began to produce ammonium nitrate as well.