The Fertility of Oita

Fields of Beppu

The meaning of “Oita,” the prefecture in which Beppu belongs, originates from the word "Okita," meaning many fields (Oita Prefectural Government). This designation refers to the complex terrain throughout the region. Between volcanic mountain ranges and seaside bays, a multitude of field-like areas and forests abounds. Perfect for vegetation, the area's drainage and soil types encourage nutrient storage.

Kuju Volcano, Oita Prefecture

Farming Land in Oita Prefecture

Beppu Bay, Oita Prefecture

The major water sources draining in and around the Oita prefecture include the Banjo, Oita, Ono, Yamakuni, and Yakkan rivers. The drainage process forms several basins from these rivers beginning with first order tributaries fed from the Sobo Katamuki mountain system, the Kuju volcanic region, and the lava plateaus of Kusu and Yabatei (“Terrain”). Most of the tributaries display radial, radiating from the peak of a volcano or mountain, or dendritic, like veins underneath skin, stream patterns. The ratio of veins to land area results in a middle to low drainage density, allowing the gathering of most tributaries into larger streams.

The drainage patterns occurring in the Oita Prefecture
Notice the lines radiating from Mount Tara (radial drainage)
and how the lines in the middle section look like a
 tree leaf (dendritic drainage).

Human hand for comparison

In comparison with Denver, Colorado (an arid area) and Kolkata, India (a super wet area), the worries of drought or flooding barely enter the conversation. The abundance of water without being overly abundant allows for a, hydrologically speaking, happy medium.

(Do not forget to look at the unit of measurement in the following graphs)

Another factor making Oita suitable for growing lies in the soil. The two main soil types in the area include Andisols and Inceptisols (Global Soil Regions). Prevalence of the first type relies on the amount of volcanic material in the area. This soil contains at least 50% volcanic ash and is naturally fertile (“Soil Orders”). The reddish browns, possibly created by podzolization in which organic matter thrives, and dark blacks, suggesting high mineral or organism content, in the soil profile create colorful strips and allow plentiful supplies of nutrient storage. 

Andisol soil profile:
Notice the dark black volcanic ash showing the A-Horizon
while the red-brown accumulation designates the B-Horizon

Also Andisol

Sources:

Global Soil Regions, http://soils.usda.gov/use/worldsoils/mapindex/order.html.

Oita Prefectural Government. Guide-O Oita Prefecture Guide Book (2006), p. 20.

“Soil Orders.” http://www4.uwsp.edu/geo/faculty/ritter/geog101/textbook/soil_systems/

soil_orders_p1.html

“Terrain and Geological Features.” Guide-O Oita Prefecture Guide Book. Web. Accessed

March 6, 2012. http://www.pref.oita.jp/10400/guide-o/eng_shizen01_new.htm

Images including graphs (in order of appearance):
https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhHFVL36sHzDikQr4BEtj9EFM3p1G5Gm74TkUvzOjFqpmuLIM4tQkBB3HsORPx2ZE2T3wNbejZrSKCD09Ur7Ts30V1YnISEocWh9SjYVEt0FfFDEpqgHdR0keUg8rbbiWGptTXO8wF2vPj7/s1600/IMG_1176.JPG
http://www.pref.oita.jp/10400/guide-o/image/gaiyo_photo/tashibu.jpg
http://static.panoramio.com/photos/original/5568551.jpg

http://www.flickr.com/photos/st-stev/1137162160/
http://earthobservatory.nasa.gov/IOTD/view.php?id=8412

http://blackpoppymag.wordpress.com/a-z-of-health/injecting-in-the-hands/

http://www.weather-and-climate.com/average-monthly-precipitation-

Rainfall,beppu,Japan

http://www.rssweather.com/climate/Colorado/Denver/

http://www.rainwaterharvesting.org/rainfall_htm/kolkata.htm
http://www.britannica.com/EBchecked/topic/23779/Andisol
http://www.ctahr.hawaii.edu/tpss/research_extension/rxsoil/andisols.htm