Re: what effects do volcanos have on their surrounding agriculture?

Many things are needed for growing good crops. Soil is just one of these 
things. The right temperature, moisture and soil are some of the most 
important. Ohio does grow fairly large quantities of corn, soybeans and 
other crops!
Volcanoes help crops grow by introducing elements crops need to grow into 
new soil [formed from volcanic ash] and old soil [formed when lava weathers 
into soil]. One element that most plants need is sulfur and most volcanoes 
introduce a new supply of this element when they erupt.
Don't confuse volcanic eruption with climate as many volcanoes in tropical 
areas have lush plant growth from warm temperatures and lots of rain. Arctic 
volcanoes support less plant growth because of the short growing season and 
much colder temperatures. Ohio lies somewhere between these climate 
extremes.
Other elements that volcanoes supply for plant growth are iron, magnesium, 
potassium, iodine, copper and manganese.