aspect of soil fertility decline. As planting is also carried out
in the winter in this area, this could cause dryness to be more
severe in the cultivated land than in other areas. These
changes occurring in the paddy fields of northern Kyushu
give us a glimpse of the possible future conditions of paddy
fields north of Kyushu, where cultivation is expected to
continue. While Japan’s paddy fields have been assessed to
require both drainage and flooding functionality, this raises
the question of how to maintain the unique permanence of
paddy fields while managing functionality to increase the
production of paddy–upland rotation fields, as well as how
to revitalize cultivated land that is in danger of losing its
permanence.
10.3 Typical Agricultural Practices and Soil
Management
10.3.1 Agricultural Production
As in other regions in Japan, agriculture in the Kyushu–
Okinawa region, southwest Japan, includes diverse sectors
such as the production of paddy rice, arable crops, vegetables, and fruits, as well as livestock farming (dairy farming
and meat production). In 2015, the total agricultural output
on a monetary basis in Kyushu (excluding Okinawa Prefecture) accounted for 19.8% of total Japanese domestic
agricultural output (Kyushu Regional Agriculture Administration Office 2017a). Of the prefectures in Kyushu and
Okinawa, the total agricultural output is highest in
Kagoshima (which ranks third among all 47 prefectures in
Japan), Miyazaki (fifth), and Kumamoto (sixth) Prefectures.
The farmland area per household in Kyushu is increasing
year by year and reached 2.11 ha in 2016. Agriculture in the
Kyushu–Okinawa region, being influenced by a warm climate and ample rainfall, can be roughly divided into a paddy
rice (Oryza sativa L.) region in northern Kyushu, a livestock
farming area in southern Kyushu, and a sugarcane (Saccharum officinarum L.)-based subtropical region in Okinawa
Prefecture and part of Kagoshima Prefecture.
Paddy rice is cultivated in the whole of the Kyushu–
Okinawa region. In particular, the contribution of agricultural output from paddy rice production to the total agricultural output is high in Fukuoka and Saga Prefectures in
northern Kyushu and Kumamoto Prefecture in central
Kyushu (Kyushu Regional Agriculture Administration
Office 2017a). Due to long-term decreasing trends in per
capita rice consumption in Japan, soybean (Glycine max L.
Merril) is widely grown instead of rice in paddies. Additionally, in the main rice-producing areas, which include
Fukuoka and Saga Prefectures, wheat (Triticum aestivum L.)
and barley (Hordeum vulgare L.) are grown as a winter crop
after rice or soybean is harvested. As a result, the production
of soybean, wheat, and barley is high in the rice-producing
areas in northern Kyushu. The warm climate and ample
rainwater allow farms to produce early delivering rice in
southern Kyushu and to perform the double cropping of rice
in Okinawa Prefecture. However, since around 1990,
extremely high temperatures in the rice-growing season have
often decreased the quality of rice grains (e.g., whitish
immature grains) (Morita 2008). As a countermeasure to
these high temperatures, the cultivation of new rice varieties
resistant to high temperatures, such as “Nikomaru,” is
increasing in northern Kyushu. As Kyushu is geographically
close to the Asian continent, rice producers there often suffer
from serious virus-mediated disease spread by migratory
planthoppers flying from the continent (Otsuka et al. 2010).
As mentioned earlier, the production of soybean, wheat,
and barley is high in rice-producing areas in northern Japan.
Since soybean is cultivated in paddy fields, the high moisture content in the soil caused by a long spell of rainy
weather limits the soybean grain yield (Tasaka and Sasaki
2005). Wheat grain produced in northern Kyushu is mainly
used for noodles. Many efforts are being made to increase
domestic wheat production, such as the use of new wheat
varieties for bread making (Tasaka and Sasaki 2005). Sweet
potato (Ipomoea batatas L.) is also an important crop produced in arable land in southern Kyushu, where volcanic
ash-derived soils are widely distributed and typhoons occur
frequently. Sweet potatoes produced in southern Kyushu
have three main uses: (1) table use (grocery store stock);
(2) material for starch production; and (3) material for shochu (a Japanese distilled alcoholic beverage) production.
Due to a recent rise in the consumption of shochu in Japan,
the production of sweet potatoes used for this purpose has
increased. In subtropical regions such as Okinawa Prefecture
and the Amami Islands (part of Kagoshima Prefecture),
sugarcane is a staple crop. Approximately, 70% of farm
households in Okinawa Prefecture cultivate sugarcane
(Okinawa General Bureau 2017).
Vegetables are widely produced across Kyushu and
Okinawa. In particular, agricultural output from the vegetable sector is high in Fukuoka, Kumamoto, and Miyazaki
Prefectures (Kyushu Regional Agriculture Administration
Office 2017a). Vegetables with a high national production
share in Kyushu include green pepper (Capsicum annuum L.
var. grossum), tomato (Solanum lycopericum L.), taro
(Colocasia esculenta (L.) Schott.), Japanese white radish
(Raphanus sativus L. var. longipinnatus), and cucumber
(Cucumis sativus L.). For fruits, a wide variety of citrus
fruits such as mandarin oranges (Citrus unshiu (Swingle)
Marcow.) are produced in Kyushu, which accounts for
approximately 30% of citrus production in Japan (production year of 2016). The production of tea (Camellia sinensis
(L.) Kuntze) is also at its most active across Kyushu, particularly in Kagoshima Prefecture. The Kyushu region
10 Kyushu and Okinawa Regions
341
in the winter in this area, this could cause dryness to be more
severe in the cultivated land than in other areas. These
changes occurring in the paddy fields of northern Kyushu
give us a glimpse of the possible future conditions of paddy
fields north of Kyushu, where cultivation is expected to
continue. While Japan’s paddy fields have been assessed to
require both drainage and flooding functionality, this raises
the question of how to maintain the unique permanence of
paddy fields while managing functionality to increase the
production of paddy–upland rotation fields, as well as how
to revitalize cultivated land that is in danger of losing its
permanence.
10.3 Typical Agricultural Practices and Soil
Management
10.3.1 Agricultural Production
As in other regions in Japan, agriculture in the Kyushu–
Okinawa region, southwest Japan, includes diverse sectors
such as the production of paddy rice, arable crops, vegetables, and fruits, as well as livestock farming (dairy farming
and meat production). In 2015, the total agricultural output
on a monetary basis in Kyushu (excluding Okinawa Prefecture) accounted for 19.8% of total Japanese domestic
agricultural output (Kyushu Regional Agriculture Administration Office 2017a). Of the prefectures in Kyushu and
Okinawa, the total agricultural output is highest in
Kagoshima (which ranks third among all 47 prefectures in
Japan), Miyazaki (fifth), and Kumamoto (sixth) Prefectures.
The farmland area per household in Kyushu is increasing
year by year and reached 2.11 ha in 2016. Agriculture in the
Kyushu–Okinawa region, being influenced by a warm climate and ample rainfall, can be roughly divided into a paddy
rice (Oryza sativa L.) region in northern Kyushu, a livestock
farming area in southern Kyushu, and a sugarcane (Saccharum officinarum L.)-based subtropical region in Okinawa
Prefecture and part of Kagoshima Prefecture.
Paddy rice is cultivated in the whole of the Kyushu–
Okinawa region. In particular, the contribution of agricultural output from paddy rice production to the total agricultural output is high in Fukuoka and Saga Prefectures in
northern Kyushu and Kumamoto Prefecture in central
Kyushu (Kyushu Regional Agriculture Administration
Office 2017a). Due to long-term decreasing trends in per
capita rice consumption in Japan, soybean (Glycine max L.
Merril) is widely grown instead of rice in paddies. Additionally, in the main rice-producing areas, which include
Fukuoka and Saga Prefectures, wheat (Triticum aestivum L.)
and barley (Hordeum vulgare L.) are grown as a winter crop
after rice or soybean is harvested. As a result, the production
of soybean, wheat, and barley is high in the rice-producing
areas in northern Kyushu. The warm climate and ample
rainwater allow farms to produce early delivering rice in
southern Kyushu and to perform the double cropping of rice
in Okinawa Prefecture. However, since around 1990,
extremely high temperatures in the rice-growing season have
often decreased the quality of rice grains (e.g., whitish
immature grains) (Morita 2008). As a countermeasure to
these high temperatures, the cultivation of new rice varieties
resistant to high temperatures, such as “Nikomaru,” is
increasing in northern Kyushu. As Kyushu is geographically
close to the Asian continent, rice producers there often suffer
from serious virus-mediated disease spread by migratory
planthoppers flying from the continent (Otsuka et al. 2010).
As mentioned earlier, the production of soybean, wheat,
and barley is high in rice-producing areas in northern Japan.
Since soybean is cultivated in paddy fields, the high moisture content in the soil caused by a long spell of rainy
weather limits the soybean grain yield (Tasaka and Sasaki
2005). Wheat grain produced in northern Kyushu is mainly
used for noodles. Many efforts are being made to increase
domestic wheat production, such as the use of new wheat
varieties for bread making (Tasaka and Sasaki 2005). Sweet
potato (Ipomoea batatas L.) is also an important crop produced in arable land in southern Kyushu, where volcanic
ash-derived soils are widely distributed and typhoons occur
frequently. Sweet potatoes produced in southern Kyushu
have three main uses: (1) table use (grocery store stock);
(2) material for starch production; and (3) material for shochu (a Japanese distilled alcoholic beverage) production.
Due to a recent rise in the consumption of shochu in Japan,
the production of sweet potatoes used for this purpose has
increased. In subtropical regions such as Okinawa Prefecture
and the Amami Islands (part of Kagoshima Prefecture),
sugarcane is a staple crop. Approximately, 70% of farm
households in Okinawa Prefecture cultivate sugarcane
(Okinawa General Bureau 2017).
Vegetables are widely produced across Kyushu and
Okinawa. In particular, agricultural output from the vegetable sector is high in Fukuoka, Kumamoto, and Miyazaki
Prefectures (Kyushu Regional Agriculture Administration
Office 2017a). Vegetables with a high national production
share in Kyushu include green pepper (Capsicum annuum L.
var. grossum), tomato (Solanum lycopericum L.), taro
(Colocasia esculenta (L.) Schott.), Japanese white radish
(Raphanus sativus L. var. longipinnatus), and cucumber
(Cucumis sativus L.). For fruits, a wide variety of citrus
fruits such as mandarin oranges (Citrus unshiu (Swingle)
Marcow.) are produced in Kyushu, which accounts for
approximately 30% of citrus production in Japan (production year of 2016). The production of tea (Camellia sinensis
(L.) Kuntze) is also at its most active across Kyushu, particularly in Kagoshima Prefecture. The Kyushu region
10 Kyushu and Okinawa Regions
341