Irazú
Irazú is the largest volcano in Central America, a beautiful National Park with a paved road to the summit. Ash from the most recent (1963-65) eruption, covered the flanks of the volcano and routinely dusted the capital of Costa Rica, San Jose, with black grit. A nuisance for city dwellers, but a calamity for coffee growers, whose plants failed to germinate seeds (coffee beans) while the ash fell. In partial compensation, the years after the eruption were bountiful, in large part due to the fresh load of minerals and trace metals delivered by the ash to the soil. In moderation, volcanic ash can be very beneficial, rejuvenating soils long exploited for crops. Howerver, thick ash buries soil and removes it from the reach of plant roots. Decades to centuries can pass before new soil develops.