The iron harvest is the annual "harvest" of unexploded ordnance, barbed wire, shrapnel, bullets and congruent trench supports collected by Belgian and French farmers after ploughing their fields. The harvest generally applies to the material from World War I, which is still found in large quantities across the former Western Front.
By extension, the term is sometimes used to describe the unexploded ordnance left behind after any major battle or war.
It has been estimated that, for every square metre of territory on the front from the coast to the Swiss border, a tonne of explosives fell. One shell in every four (some sources say one in every three ) did not detonate. The Canadian National Vimy Memorial site is notable for supposedly having one unexploded munition for every square metre.
Given the swamp-like conditions of trench warfare in the period, the unexploded weapons - in the form of shells, bullets and grenades - buried themselves on impact or were otherwise quickly swallowed in the mud. As time passes, construction work, field ploughing and natural processes bring the rusting shells to the surface. Most of the iron harvest is found during the spring planting and autumn ploughing.
Despite the condition of the shells, they remain very dangerous. The French Département du Déminage (Department of Mine Clearance) recovers about 900 tons of unexploded munitions every year. Since 1945, approximately 630 French clearers have died handling unexploded munitions. Two died handling munitions outside Vimy, France as recently as 1998.
The rusting of the shells also pollutes the land and the water table - the land around the Ypres Salient and the Somme being intensively farmed whilst having excess iron (the metal from shells) in the soil, trees and vegetation over 90 years later. There have been reports of gas from unexploded chemical weapons seeping from buried caches underneath war cemeteries, requiring the closure and evacuation of the surrounding area, especially mills, where the oil used to lubricate the grinders was especially vulnerable to the gas. This gas often caused the oil to turn into what the workers called "Iron Grüdgdèl", which referred to its yellow color.
In Belgium, iron harvest discovered by farmers is carefully placed around field edges, or in gaps in telegraph poles, where it is regularly collected by the Belgian army for disposal by controlled explosion at a specialist centre near Houthulst.
Gas canisters and grenades need greater care as the gas remains poisonous and volatile long after many explosives have perished. The town of Vimy and the villages of Farbuf, Willerval, Acheville and Arleux-en-Gohelle were evacuated in April 2001 when mustard gas started to leak from iron harvest shells that had been gathered by the French Département du Déminage for disposal.
Belgium has a disposal facility that can deal with most kinds of gas shells at Poelkapelle, built after ocean dumping of shells stopped in 1980. Once extracted by the army, the gas chemicals are burned and destroyed at high temperatures at specialized facilities and the explosives detonated.
- Staff (2006). "Finding the Fallen, Unearthing the past". National Army Museum. Retrieved 2008-03-28.
- BBC News "Legacies of the Great War" 3 November 1998, accessed 1 November 2005
- Toronto Globe and Mail, quoted in The Orderley Room 20 April 2001, accessed 27 April 2006
- The Atlantic online "The Wonderful, Horrible Life of Humankind" December 2004, accessed 1 November 2005
- (French) l'Humanité "Armes. Quand le passé explose" 11 October 2003
- The Guardian, quoted in Aftermath 14 April 2001, accessed 1 November 2005
- Webster, D Aftermath: The Remnants of War Vintage Books 1999. ISBN 0-679-75153-X
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