concentrations in well water are particularly observed in the
northern part of Kumamoto Prefecture, which contains arable land, horticulture, and livestock farming areas. Furthermore, in the Miyakonojo basin region in Miyazaki
Prefecture, where cropping and livestock farming are the
primary industries, NO 3
− concentrations in well water also
exceeded 10 mg N L
−1 in 16% of 782 wells surveyed in
1998 (Miyazaki Prefecture 2004).
Many studies have been conducted in wide areas of
Kyushu to identify the mechanism of NO 3
− contamination in
groundwater and to establish efficient countermeasures in
agricultural areas. Lysimeter experiments conducted in
Miyakonojo City showed that the amount of NO 3
− leaching
in different soils was due to cumulative water permeability
following fertilizer application (Kobayashi et al. 1994).
15 N-labeling experiments revealed that NO 3
− contamination
in water in a well (18.5 m depth) could be projected by
cumulative precipitation (4158 mm) in a farmland with
long-term application of slurry from dairy cattle (Niimi
2002). By analyzing isotopes of nitrogen, oxygen, carbon,
sulfur, and hydrogen in groundwater and by measuring
dissolved oxygen and dissolved organic carbon contents in
groundwater, the dynamics of NO 3
− in groundwater were
studied in the Kumamoto region and the Miyakonojo basin
region. As a result, the regional-scale transport and disappearance of NO 3
− in groundwater was elucidated (Mori et al.
2016). The information obtained was provided to administrators of local governments to establish viable countermeasures for NO 3
− contamination in groundwater.
In Kumamoto Prefecture, an item on NO 3
− was added to
the “Kumamoto Prefectural Ordinance on Groundwater
Conservation” in 2012 to promote the appropriate application of fertilizers and management of animal wastes to
reduce the NO 3
− contamination of groundwater (Kumamoto
Prefecture 2000). Additionally, Kumamoto Prefecture
established a framework which awards certification to agricultural products produced under farming practices which
contribute to groundwater conservation, thus allowing consumers to purchase such agricultural products selectively to
support activities for NO 3
− reduction (Kumamoto Prefecture
2015).
In the Miyakonojo basin region, the “Council on
Groundwater Conservation in the Miyakonojo Basin” was
first organized by local municipalities and Miyazaki
University in 1995 and continued to monitor NO 3
− concentration in groundwater (Miyazaki Prefecture 2004). In 2003,
the Miyazaki prefectural government established a council to
reduce NO 3
− contamination in groundwater in the Miyakonojo basin region and in 2004 announced concrete plans to
reduce NO 3
− concentrations in all well waters in the region to
below 10 mg N L
−1 (Miyazaki Prefecture 2004). The council
was organized by a wide range of personnel and formulated
comprehensive countermeasures regarding activities such as
animal waste management, fertilizer application, and
household waste-water management. As a result of these
activities, the percentage of wells whose water had NO 3
−
contents exceeding 10 mg N L
−1 in 2017 was only 4.8%,
one-third what it was in 1998 (Miyakonojo City 2017).
10.4.3 Greenhouse Gas Emission
The appropriate management of livestock manure and its
effective utilization are important issues. In this section,
studies concerning the emissions of greenhouse gases, nitrous oxide (N 2 O) in particular, from soils applied with
livestock manure are introduced.
Niimi (2002) investigated the nitrogen dynamics in the
Andosol field of the Kyushu–Okinawa Agricultural
Research Center, National Agriculture and Food Research
Organization (Miyakonojo, Miyazaki Prefecture), where
forage corn (Zea mays L.) and Italian rye grass (Lolium
multiflorum Lam.) were cropped year-round for five years
from 1992 to 1997. In the experiment, cattle manure slurry
fertilizer was applied to the crops at three different rates for
each crop cultivation, 60 Mg ha
−1 (standard), 150, and
300 Mg ha
−1 , and N 2 O flux was also measured. The mean
cumulative N 2 O–N emission rates for five years accounted
for 0.4% of the total nitrogen amount applied in the 60 and
150 Mg ha
−1 plots, close to the average value in Japanese
fields (0.62%; Akiyama et al. 2006), but accounted for 4.6%
in the 300 Mg ha
−1 plots, which is comparable with the
value observed in acidic tea fields, where N 2 O is emitted at
the highest rate in Japan (e.g., Tokunaga et al. 1996).
Additionally, Uezono et al. (2013) studied the relationship between cumulative N 2 O emission rates from soils to
which hog and poultry manure composts were applied and
the amount of acid detergent (AD) soluble nitrogen in the
manure composts, by incubation experiments. There was a
positive correlation (r = 0.88, p < 0.01) between the emission rates and the amount of AD soluble nitrogen, which was
thus shown to be a possible indicator for estimating N 2 O
emission rates from soils treated with livestock manure
composts.
As for the N 2 O emissions after the application of Manure
compost pellets (MCPs) to soils, it was reported that N 2 O
emissions were 3–9 times higher after the application of
MCPs than after the application of ordinary manure compost
or chemical fertilizer during the cultivation period (Inoue
and Shibukawa 2008; Yamane and Yamada 2009). In these
studies, N 2 O emission peaked soon after the application of
MCPs (within a week) and the peak emission was considered to derive from the denitrification in pellets. However,
Yamane et al. (2011) reported that cumulative N 2 O emission
10 Kyushu and Okinawa Regions
353
northern part of Kumamoto Prefecture, which contains arable land, horticulture, and livestock farming areas. Furthermore, in the Miyakonojo basin region in Miyazaki
Prefecture, where cropping and livestock farming are the
primary industries, NO 3
− concentrations in well water also
exceeded 10 mg N L
−1 in 16% of 782 wells surveyed in
1998 (Miyazaki Prefecture 2004).
Many studies have been conducted in wide areas of
Kyushu to identify the mechanism of NO 3
− contamination in
groundwater and to establish efficient countermeasures in
agricultural areas. Lysimeter experiments conducted in
Miyakonojo City showed that the amount of NO 3
− leaching
in different soils was due to cumulative water permeability
following fertilizer application (Kobayashi et al. 1994).
15 N-labeling experiments revealed that NO 3
− contamination
in water in a well (18.5 m depth) could be projected by
cumulative precipitation (4158 mm) in a farmland with
long-term application of slurry from dairy cattle (Niimi
2002). By analyzing isotopes of nitrogen, oxygen, carbon,
sulfur, and hydrogen in groundwater and by measuring
dissolved oxygen and dissolved organic carbon contents in
groundwater, the dynamics of NO 3
− in groundwater were
studied in the Kumamoto region and the Miyakonojo basin
region. As a result, the regional-scale transport and disappearance of NO 3
− in groundwater was elucidated (Mori et al.
2016). The information obtained was provided to administrators of local governments to establish viable countermeasures for NO 3
− contamination in groundwater.
In Kumamoto Prefecture, an item on NO 3
− was added to
the “Kumamoto Prefectural Ordinance on Groundwater
Conservation” in 2012 to promote the appropriate application of fertilizers and management of animal wastes to
reduce the NO 3
− contamination of groundwater (Kumamoto
Prefecture 2000). Additionally, Kumamoto Prefecture
established a framework which awards certification to agricultural products produced under farming practices which
contribute to groundwater conservation, thus allowing consumers to purchase such agricultural products selectively to
support activities for NO 3
− reduction (Kumamoto Prefecture
2015).
In the Miyakonojo basin region, the “Council on
Groundwater Conservation in the Miyakonojo Basin” was
first organized by local municipalities and Miyazaki
University in 1995 and continued to monitor NO 3
− concentration in groundwater (Miyazaki Prefecture 2004). In 2003,
the Miyazaki prefectural government established a council to
reduce NO 3
− contamination in groundwater in the Miyakonojo basin region and in 2004 announced concrete plans to
reduce NO 3
− concentrations in all well waters in the region to
below 10 mg N L
−1 (Miyazaki Prefecture 2004). The council
was organized by a wide range of personnel and formulated
comprehensive countermeasures regarding activities such as
animal waste management, fertilizer application, and
household waste-water management. As a result of these
activities, the percentage of wells whose water had NO 3
−
contents exceeding 10 mg N L
−1 in 2017 was only 4.8%,
one-third what it was in 1998 (Miyakonojo City 2017).
10.4.3 Greenhouse Gas Emission
The appropriate management of livestock manure and its
effective utilization are important issues. In this section,
studies concerning the emissions of greenhouse gases, nitrous oxide (N 2 O) in particular, from soils applied with
livestock manure are introduced.
Niimi (2002) investigated the nitrogen dynamics in the
Andosol field of the Kyushu–Okinawa Agricultural
Research Center, National Agriculture and Food Research
Organization (Miyakonojo, Miyazaki Prefecture), where
forage corn (Zea mays L.) and Italian rye grass (Lolium
multiflorum Lam.) were cropped year-round for five years
from 1992 to 1997. In the experiment, cattle manure slurry
fertilizer was applied to the crops at three different rates for
each crop cultivation, 60 Mg ha
−1 (standard), 150, and
300 Mg ha
−1 , and N 2 O flux was also measured. The mean
cumulative N 2 O–N emission rates for five years accounted
for 0.4% of the total nitrogen amount applied in the 60 and
150 Mg ha
−1 plots, close to the average value in Japanese
fields (0.62%; Akiyama et al. 2006), but accounted for 4.6%
in the 300 Mg ha
−1 plots, which is comparable with the
value observed in acidic tea fields, where N 2 O is emitted at
the highest rate in Japan (e.g., Tokunaga et al. 1996).
Additionally, Uezono et al. (2013) studied the relationship between cumulative N 2 O emission rates from soils to
which hog and poultry manure composts were applied and
the amount of acid detergent (AD) soluble nitrogen in the
manure composts, by incubation experiments. There was a
positive correlation (r = 0.88, p < 0.01) between the emission rates and the amount of AD soluble nitrogen, which was
thus shown to be a possible indicator for estimating N 2 O
emission rates from soils treated with livestock manure
composts.
As for the N 2 O emissions after the application of Manure
compost pellets (MCPs) to soils, it was reported that N 2 O
emissions were 3–9 times higher after the application of
MCPs than after the application of ordinary manure compost
or chemical fertilizer during the cultivation period (Inoue
and Shibukawa 2008; Yamane and Yamada 2009). In these
studies, N 2 O emission peaked soon after the application of
MCPs (within a week) and the peak emission was considered to derive from the denitrification in pellets. However,
Yamane et al. (2011) reported that cumulative N 2 O emission
10 Kyushu and Okinawa Regions
353