12.9 km
2 ; flowers: 10.2 km
2 ) (Ministry of Agriculture,
Forestry, and Fisheries 2015). The major greenhouse crops
in this region are tomato (Solanum lycopersicum), melon
(Cucumis melo L), watermelon (Citrullus lanatus), cucumber (Cucumis sativus L.), strawberry (Fragaria L.), sweet
pepper (Capsicum annuum L.), chrysanthemum (Chrysanthemum L.), and citrus fruits inherent to this area such as
“Banpeiyu” pummelo (Citrus grandis, Citrus maxima) and
“Shiranui” mandarin ((Citrus unshiu  C. sinensis)  C.
reticulata). Fruit trees of tropical origin such as mango
(Mangifera indica) are also cultivated in greenhouses.
The physicochemical properties of Japanese soils were
investigated nationwide in the Soil-Environmental Monitoring Project from 1979 to 1998 (Obara and Nakai 2004).
This survey identified the excessive accumulation of
exchangeable bases and phosphorus in the soils of greenhouse crops. Due to the extreme increase in the prices of
phosphate ores for fertilizer in 2008, the amount of phosphate fertilization was subsequently reduced. Regarding
fertilizer components other than phosphorus, efforts to make
application rates more appropriate have been addressed by
local governments. The proper fertilization values for crops
including tomato, watermelon, eggplant (Solanum), sweet
pepper, okra (Abelmoschus esculentus), chingen sai (Brassica rapa var. chinensis), lettuce (Lactuca sativa), orange
(Citrus unshiu), mango, and chrysanthemum are published
on the website of each prefecture (e.g., Okinawa Agricultural
Research Center 2015; Mimaki 2016).
In the cultivation of tomato, an important crop in
southern Kyushu, active fostering and suppressive cultivation modes are conducted from autumn to spring. Tomato
yellow leaf curl disease and other soil diseases and pests are
likely to result from repeated and long-term cultivation
(Nagatomo 2004). In tomato and other crops, “soil solarization,” in which phytopathogens in the soil are killed by
raising the soil temperature by covering the soil surface
with transparent film in the summer, has been used practically (Shiraki 2007). In Miyazaki Prefecture, a method to
stabilize the disinfection effect of soil solarization and to
reduce the use of chemical fertilizer by applying some
condensed grain distillers soluble of “shochu” spirit prior to
soil solarization was documented (Miyazaki Agricultural
Research Institute 2016b).
In order to increase the productivity of greenhouse crops,
in recent years, facilities equipped with CO 2 gas application
systems, drip irrigation and liquid fertilization systems, and
so on, have been established. Large-scale facilities are in
operation in Kumamoto City, and fertilization methods
adapted to new cultivation environments are also studied
(Kumamoto Prefectural Agricultural Research Center, 2017).
10.3.6 Upland Crop Production in Southern
Kyushu
Southern Kyushu, which extends more than 600 km from
south to north, contains Kagoshima and Miyazaki Prefectures, which have average yearly temperatures of 19.2 °C
and average annual rainfall of approximately 2000–
3000 mm. Agricultural production in both prefectures
mainly includes sweet potato (Ipomoea batatas L.), vegetables, livestock farming, flowering plants, and tea
(Camellia sinensis (L.) Kuntze.) by taking advantage of the
mild weather and vast area of agricultural fields. This region
is distant from mass consuming regions, and crops such as
potatoes (Solanum tuberosum L.), taro (Colocasia esculenta
(L.) Schott), and fava beans (Vicia faba L.) are shipped in a
relay system.
Upland fields in Kagoshima Prefecture consist of Andosols, which account for 67% of all upland fields, Red-Yellow
soils (14%), and Eutrosols (8%). Upland fields in Miyazaki
Prefecture are located on hilly areas generated in the Paleogene period, Pleistocene terraces, and the Shirasu Plateau in
the southwest of the prefecture, and Andosols with a base
material of volcanic ash account for 90% of these fields.
Additionally, a very small amount of dune immature soil and
Brown Fluvic soils are distributed along river banks and in
river basins, respectively.
According to national and prefectural soil monitoring
projects conducted during 1979–2008, the content of
exchangeable calcium, as measured during six survey cycles,
had a decreasing trend in vegetable fields and was almost
constant in staple crop fields and forage crop fields. The soil
content of exchangeable magnesium also showed a
decreasing trend. The content of exchangeable potassium
was constant in staple crop fields and vegetable fields and
tended to decrease in other fields. The content of available
phosphate showed a leveling off trend in staple crop fields
and a rising trend in vegetable, forage crop, and tea fields
(Fig. 10.12; Nishi et al. 2013).
The content of soil available phosphate has been
increasing in southern Kyushu, and it is excessively accumulated. This has been causing concern about a decline in
productivity caused by crop physiological disorders, and so
on. Implementing proper fertilization while taking into
consideration, the nutrients that have accumulated in soils
allow the maintenance of soils and the reduction of fertilization cost.
Nagatomo et al. (2017) considered the proper amount of
fertilizer for phosphate in Chinese cabbage (Brassica rapa
var. pekinensis) in Andosols. They set up two plots with
different levels of soil phosphate fertility—100 and
346
Y. Arakawa et al.
2 ; flowers: 10.2 km
2 ) (Ministry of Agriculture,
Forestry, and Fisheries 2015). The major greenhouse crops
in this region are tomato (Solanum lycopersicum), melon
(Cucumis melo L), watermelon (Citrullus lanatus), cucumber (Cucumis sativus L.), strawberry (Fragaria L.), sweet
pepper (Capsicum annuum L.), chrysanthemum (Chrysanthemum L.), and citrus fruits inherent to this area such as
“Banpeiyu” pummelo (Citrus grandis, Citrus maxima) and
“Shiranui” mandarin ((Citrus unshiu  C. sinensis)  C.
reticulata). Fruit trees of tropical origin such as mango
(Mangifera indica) are also cultivated in greenhouses.
The physicochemical properties of Japanese soils were
investigated nationwide in the Soil-Environmental Monitoring Project from 1979 to 1998 (Obara and Nakai 2004).
This survey identified the excessive accumulation of
exchangeable bases and phosphorus in the soils of greenhouse crops. Due to the extreme increase in the prices of
phosphate ores for fertilizer in 2008, the amount of phosphate fertilization was subsequently reduced. Regarding
fertilizer components other than phosphorus, efforts to make
application rates more appropriate have been addressed by
local governments. The proper fertilization values for crops
including tomato, watermelon, eggplant (Solanum), sweet
pepper, okra (Abelmoschus esculentus), chingen sai (Brassica rapa var. chinensis), lettuce (Lactuca sativa), orange
(Citrus unshiu), mango, and chrysanthemum are published
on the website of each prefecture (e.g., Okinawa Agricultural
Research Center 2015; Mimaki 2016).
In the cultivation of tomato, an important crop in
southern Kyushu, active fostering and suppressive cultivation modes are conducted from autumn to spring. Tomato
yellow leaf curl disease and other soil diseases and pests are
likely to result from repeated and long-term cultivation
(Nagatomo 2004). In tomato and other crops, “soil solarization,” in which phytopathogens in the soil are killed by
raising the soil temperature by covering the soil surface
with transparent film in the summer, has been used practically (Shiraki 2007). In Miyazaki Prefecture, a method to
stabilize the disinfection effect of soil solarization and to
reduce the use of chemical fertilizer by applying some
condensed grain distillers soluble of “shochu” spirit prior to
soil solarization was documented (Miyazaki Agricultural
Research Institute 2016b).
In order to increase the productivity of greenhouse crops,
in recent years, facilities equipped with CO 2 gas application
systems, drip irrigation and liquid fertilization systems, and
so on, have been established. Large-scale facilities are in
operation in Kumamoto City, and fertilization methods
adapted to new cultivation environments are also studied
(Kumamoto Prefectural Agricultural Research Center, 2017).
10.3.6 Upland Crop Production in Southern
Kyushu
Southern Kyushu, which extends more than 600 km from
south to north, contains Kagoshima and Miyazaki Prefectures, which have average yearly temperatures of 19.2 °C
and average annual rainfall of approximately 2000–
3000 mm. Agricultural production in both prefectures
mainly includes sweet potato (Ipomoea batatas L.), vegetables, livestock farming, flowering plants, and tea
(Camellia sinensis (L.) Kuntze.) by taking advantage of the
mild weather and vast area of agricultural fields. This region
is distant from mass consuming regions, and crops such as
potatoes (Solanum tuberosum L.), taro (Colocasia esculenta
(L.) Schott), and fava beans (Vicia faba L.) are shipped in a
relay system.
Upland fields in Kagoshima Prefecture consist of Andosols, which account for 67% of all upland fields, Red-Yellow
soils (14%), and Eutrosols (8%). Upland fields in Miyazaki
Prefecture are located on hilly areas generated in the Paleogene period, Pleistocene terraces, and the Shirasu Plateau in
the southwest of the prefecture, and Andosols with a base
material of volcanic ash account for 90% of these fields.
Additionally, a very small amount of dune immature soil and
Brown Fluvic soils are distributed along river banks and in
river basins, respectively.
According to national and prefectural soil monitoring
projects conducted during 1979–2008, the content of
exchangeable calcium, as measured during six survey cycles,
had a decreasing trend in vegetable fields and was almost
constant in staple crop fields and forage crop fields. The soil
content of exchangeable magnesium also showed a
decreasing trend. The content of exchangeable potassium
was constant in staple crop fields and vegetable fields and
tended to decrease in other fields. The content of available
phosphate showed a leveling off trend in staple crop fields
and a rising trend in vegetable, forage crop, and tea fields
(Fig. 10.12; Nishi et al. 2013).
The content of soil available phosphate has been
increasing in southern Kyushu, and it is excessively accumulated. This has been causing concern about a decline in
productivity caused by crop physiological disorders, and so
on. Implementing proper fertilization while taking into
consideration, the nutrients that have accumulated in soils
allow the maintenance of soils and the reduction of fertilization cost.
Nagatomo et al. (2017) considered the proper amount of
fertilizer for phosphate in Chinese cabbage (Brassica rapa
var. pekinensis) in Andosols. They set up two plots with
different levels of soil phosphate fertility—100 and
346
Y. Arakawa et al.