(TheLocal) - In their fields of vines in deepest Spain, the winemakers at the Jesús del Perdón cooperative smiled last August: the blend of rain and sun promised a bumper grape crop. They just didn't realize how big it would be.
 
The massive crop vaulted Spain to the world's biggest wine producer, forcing its vintners to compete abroad in a tough market to sell off the surplus.

Spain overall produced 50 million hectolitres (6.7 billion bottles) of wine in 2013, a 41 percent surge from 2012, the Spanish agriculture ministry says.

The ministry's figure for Spanish production exceeds the estimates from the Italian and French wine industries for their own production — 47 million and 42 million hectolitres respectively.

The definitive production figures from the International Organisation of Wine and Vine are published in May. But if confirmed, they would give Spain another industry to look to for exports to build a lasting recovery from the burst property bubble that has hobbled the economy since 2008.

Even Rafael del Rey, director of the Spanish Wine Market Observatory, admitted he found it "most surprising" that Spain leapt ahead to become the top wine producer in the world in 2013.

While weather helped -- last summer the country enjoyed the usual sunny weather plus enough rain to really water the vines — the rise in Spanish production is also the result of a drive to increase productivity.

"We have spent many years investing in improving the vineyards", said del Rey.

Twenty five years ago, Spanish vineyards had average yield of 17 hectolitres per hectare -- "very low", said Roca. But in recent years the yield has reached about 50 hectolitres per hectare.

Older, less productive vines have been torn up and vineyards made more efficient by replacing handpicking with machines where possible.

"The vineyards' productivity has improved noticeably," del Rey said.