Volcanoes and men - 2 - The volcanic fertility.

Besides a strategic advantage, volcanoes have interesting characteristics identified by the ancients : the volcanic soils are very fertile. This is why, despite the risk of eruption, many farmers living in the direct vicinity of volcanoes.

Indeed, volcanic ash is rich in minerals and trace elements, potassium, iron, magnesium, manganese, etc..
At the beginning of eruptive activity, of course, these projections kill all vegetation. Gradually, these particles are altered in small grains under 2 microns in diameter: it is the process of starting argilisation.
But the weather and the soil pH must follow ... if it's hot and humid, and the crops will be promoted on the slopes of the volcano.

Indonésie - Bromo eruption of ash will cover the farmland outside the Tengger caldera - Photo Trisnadi / AP / 11.03.2011

Indonésie / Java: Vegetable crops in the morning mist at Cemoro Lawang, a village near the caldera of Bromo-Tengger - Photo What an amazing world.

In Indonesia, vegetables on the slopes of Merapi, or close to the Tengger caldera, are rich and support a large population of Java. Local farmers can make up in volcanic soils to four or five crops of rice annually, against one or two elsewhere.
In Sicily, the slopes of Etna allow the production of citrus while the surrounding limestone hills are dry.
In Costa Rica, the slopes of the Poas are home to coffee, flowers and various vegetables crops.

             Costa Rica - coffee on the slopes of Poas Volcano - Photo Bernard Duyck

By cons, in Iceland, where the climate is too cold, the beneficial effect of volcanic soil does not occur.

We realized early the advantage of the volcanic land for the cultivation of the vine, one of the pillars of ancient agriculture. The wine of Vesuvius and Etna were famous and made the wealth of surrounding cities. Pliny talk about the wine Aminneum of Mount Vesuvius and the vine Pompeiana, very productive through the rich earth where it is planted. Frescoes represent the lower slopes of the volcano covered with vines, held by poles, and Bacchus, covered with grapes, holding thyrsus, panther at feet ... personification of the vine that was dear to him.

Pompeii - Casa del Centenario - fresco of Bacchus before Vesuvius.

The volcanic ash and slag properties improving the soil structure. They promote drainage, which promotes the vine, which does not like standing water at the roots.

 The Lacryma Christi of Vesuvius, the Malvasia of Lipari and Salina, the vineyards of Auvergne, or Salagou or Malvasia of Lanzarote are all witnesses.

 
            Canary Islands - Lanzarote - vineyards of La Geria - Jerome Photo / World travel

On this Canary Island, dry and arid, farmers have developed an unique culture's technique : at La Geria, they plant the vines in deep holes to reach the topsoil prior to eruptions, and covered with " rofe ", a layer of volcanic ash and lapilli, which lets passes the moisture and prevents its evaporation during the day. The vines are protected from the wind by semi-circular stone walls, the "Zocos ". The vino Malvasia, golden, fresh and highly alcoholic, represents the victory of the tenacity on the hostility of the earth.

              Japan - a big daikon still covered with ash from Sakura-jima - Photo Antony Van Eeten

Other examples in Japan, where giant white radish, daikon, are produced on these volcanic lands ... or in Chile, where after the eruption of the Hudson in 1991, more than 600,000 head of cattle were killed by volcanic ash ... they have however fertilization of Argentine Patagonia valley now produces cherries for export.