LEPERSTRAAT, BELGIUM –Luk Delva flinches each time he hears an unusual metallic noise as he's harvesting or plowing fields here in Western Europe. More often than not, that noise is an unexploded WWI shell jamming his equipment.

Thanks to the natural shifting of the soil, armaments from the Great War (1914-1918) keep surfacing long after the armistice was signed. More than 40 million shells were fired during the war; about a third never detonated. Some 10,000 shells turn up each year.

"Sometimes when I hear a big bang in the machine and nothing happens I say, 'I'm lucky,'" says Delva (left, with artillery shell), who raises feeder pigs and about 300 acres of sugar beets and potatoes.

Delva and countless Belgian farmers like him still unearth mustard gas containers, artillery shells, rifles, unexploded grenades and shrapnel from one of the most brutal conflicts in human history. Over 15 million people died and most of the conflict took place along a narrow 50 by 20 mile strip of land here.

Photos of the region after the war show a moon-like, obliterated landscape littered with demolished homes and cratered farm fields. It was here in 1915 that Canadian physician and Lieutenant Colonel John McCrae was inspired to write the poem "In Flanders Fields," after seeing his 22-year-old comrade die in action.

Last post

I only came to appreciate all of this as an observer with our tour of International Federation of Agricultural Journalists passing through this historic region of eastern Belgium late last week. Each evening at 8 p.m. at Ypres, a ceremony called 'The Last Post' honors soldiers who died but were never found or properly buried (about 250,000 bodies were never recovered).

The ceremony has taken place every day since 1928 and is held beneath the Menin Gate Memorial to the Missing, with its somber columns etched with the names, rank, brigade and nationality of these lost soldiers. Ypres is where German soldiers first used poison gas in 1915.

According to Belgian law, when a farmer finds a bomb he must stop his machines, carefully place the ordnance at the side of his field and call a special bomb disposal squad. This squad retrieves the material, and daily detonates or destroys them. Last year they collected 550,000 pounds of unexploded munitions and shrapnel says Johan Vandewalle, who co-wrote an exceptional expose on the lives of WWI soldiers in a book called Beneath Flanders Fields.

"For a farmer, sometimes they plow and sometimes these bombs explode," he says. "It's very, very dangerous."

Trench warfare

Delva and Vandewalle worry even more about the hundreds of underground trenches still intact beneath these fields. During the war, tunnelers built deep dugouts and claustrophobic bunkers that housed tens of thousands of soldiers. These giant subterranean mazes were built like mine shafts with wooden supports.

As years pass these hidden structures weaken and collapse, causing people and farm equipment to suddenly and literally disappear into the ground, sometimes with tragic results, says Karolien Cools, a consultant for the Belgian Farmers Union.

"If you want to farm in Belgium, you have to accept the danger," she says.

Vandewalle has spent a lifetime researching the war's trenches and dugouts. He was on hand at Delva's farm to give a detailed description of the munitions. Many people have fallen into this swampy muck and been trapped, he says.

When a dugout is discovered, topsoil is removed and an excavation takes place. Sometimes digging machines themselves get swallowed up in the process.

I don't think you'll find any of these concerns in your average farm safety manual. Then again, maybe this is how history continues to remind us of the tragedy of war. In our post-tour bus rides, few of us could recall why the war was fought in the first place. But we sure got a feel for the people who were bombed, and the farmers who continue to worry about being bombed today.

LEFT: A Belgian farm wife shows off a British army helmet found in herfields, along with other weapons from WWI.