treatment followed by the distribution of manure as organic
fertilizer.
Manure can be treated by techniques such as drying,
anaerobic digestion, composting, and so on. Of these
methods, composting is the most popular in Japan
(Table 10.5), which makes the application of manure more
manageable. Composting is generally defined as the biological oxidative decomposition of organic constituents in
wastes under controlled conditions. A high temperature
(greater than 60 °C) generated during manure composting
contributes to killing weed seeds and pathogens, the evaporation of water, and the resulting production of sanitary
compost.
(1) Pelletized compost
As mentioned in 8.2.3, compost granulation contributes to
the correction of regional manure surpluses in concentrated
livestock areas if the usable product is transported and
applied to the soil where organic amendment is lacking for
maintaining soil fertility.
A further advantage of compost granulation is that it
results in a greater phosphorus (P) recovery rate (Arakawa
2012a, b). In a study, P availability between single superphosphate and two forms of compost, pelletized compost, a
1:1 mixture of cattle manure compost and poultry litter, and
the corresponding ungranulated compost, was examined
using komatsuna (Brassica Campestris L.) and buckwheat
(Fagopyrum esculentum Moench) as indicator crops. Total P
uptake increased in a curvilinear manner with increasing
application rates for all three fertilizer materials, while the
average P recovery rate was much higher with pelletized
compost than with ungranulated compost for both crops, and
was comparable to that of superphosphate. Meanwhile, the
researchers observed the plant roots were winding outside of
the compost granules. The factors affecting improved P
efficiency were investigated by Takahashi et al. (2016). The
fate of P was investigated in an incubation study using
pelletized and ground pelletized poultry manure compost as
amendments to an Andosol under five levels of moisture
content. Compost amendment increased levels of Truog P
and labile inorganic P in the soil, as earlier reported. A
greater increase of these P fractions, which was mainly
attributable to a decreased soil level of phytate-like organic
P, was observed in the soil amended with pelletized compost
compared with the soil amended with ground compost. The
researchers also observed that P mineralization was
enhanced under higher moisture content. The improvement
in the availability of compost P in pelletized compost can be
explained as follows: (1) Organic amendments prevent the
rapid fixation of available P in soil by blocking P adsorption
sites (Haynes and Mokolobate 2001); (2) phytate-like
organic P in the compost may be satisfactorily mineralized
under high moisture content of the pellets; (3) inorganic P
inside of the pellets may be fixation-avoidable since it does
not contact with soil colloids; then (4) crop roots may efficiently absorb P from the compost granules.
(2) Compost-mixed compound fertilizer
In accordance with the Fertilizer Regulation Act (Act No. 127 of
1950), it had been prohibited to fortify compost with normal
fertilizers, such as nitrogenous mineral fertilizers. However, since
2014, a new official fertilizer specification, “compost-mixed
compound fertilizer,” was enacted, and now, it is possible to
register and manufacture fertilizers using composted manure
and/or composted food waste for fertilizer materials in the course
of business. For this granulated fertilizer, the amount of nutrients
are balanced, and the minimum amount of each nutrient is
guaranteed and clearly indicated, which makes it usable in the
same way as other compound fertilizers (Katoh 2017). Encouraging the increased use of this type of fertilizer in Japan is
expected to reduce the dependence on imported fertilizer
resources and reduce the cost of fertilizer in agriculture systems.
10.4.2 Nitrate Contamination of Groundwater
On Kyushu, welded tuff layers with a very low water permeability are mostly found on the edge of pyroclastic
deposit areas, and rainwater is ample (more than 2000 mm
of annual precipitation), and these geographical and meteorological conditions allow the storage of ample groundwater
in large parts of the island. Groundwater is extremely
important for domestic water supply in the southern part of
Kyushu. In particular, the Kumamoto region and the Miyakonojo basin region depend on groundwater for almost
100% of their domestic water supply, which supports populations of about 1 million and 240,000, respectively.
Some of the Nansei Islands, such as Miyako, Okinoerabu,
and Kikai Islands, are composed of limestones derived from
coral. Since there is a layer with a very low water permeability under the limestone layer, groundwater is retained in
the below ground part of those islands. Agriculture and daily
life in those islands are largely dependent on groundwater.
Despite the importance of groundwater in communities in
Kyushu and some of the Nansei Islands, nitrate (NO 3
− )
contamination of groundwater has long been a local environmental issue. For example, in Kumamoto Prefecture,
21% of 370 wells surveyed in 2012 contained NO 3
− concentrations higher than 10 mg N L
−1 (the water quality
standard in Japan) (Kumamoto Prefecture 2013). High NO 3
−
352
Y. Arakawa et al.
fertilizer.
Manure can be treated by techniques such as drying,
anaerobic digestion, composting, and so on. Of these
methods, composting is the most popular in Japan
(Table 10.5), which makes the application of manure more
manageable. Composting is generally defined as the biological oxidative decomposition of organic constituents in
wastes under controlled conditions. A high temperature
(greater than 60 °C) generated during manure composting
contributes to killing weed seeds and pathogens, the evaporation of water, and the resulting production of sanitary
compost.
(1) Pelletized compost
As mentioned in 8.2.3, compost granulation contributes to
the correction of regional manure surpluses in concentrated
livestock areas if the usable product is transported and
applied to the soil where organic amendment is lacking for
maintaining soil fertility.
A further advantage of compost granulation is that it
results in a greater phosphorus (P) recovery rate (Arakawa
2012a, b). In a study, P availability between single superphosphate and two forms of compost, pelletized compost, a
1:1 mixture of cattle manure compost and poultry litter, and
the corresponding ungranulated compost, was examined
using komatsuna (Brassica Campestris L.) and buckwheat
(Fagopyrum esculentum Moench) as indicator crops. Total P
uptake increased in a curvilinear manner with increasing
application rates for all three fertilizer materials, while the
average P recovery rate was much higher with pelletized
compost than with ungranulated compost for both crops, and
was comparable to that of superphosphate. Meanwhile, the
researchers observed the plant roots were winding outside of
the compost granules. The factors affecting improved P
efficiency were investigated by Takahashi et al. (2016). The
fate of P was investigated in an incubation study using
pelletized and ground pelletized poultry manure compost as
amendments to an Andosol under five levels of moisture
content. Compost amendment increased levels of Truog P
and labile inorganic P in the soil, as earlier reported. A
greater increase of these P fractions, which was mainly
attributable to a decreased soil level of phytate-like organic
P, was observed in the soil amended with pelletized compost
compared with the soil amended with ground compost. The
researchers also observed that P mineralization was
enhanced under higher moisture content. The improvement
in the availability of compost P in pelletized compost can be
explained as follows: (1) Organic amendments prevent the
rapid fixation of available P in soil by blocking P adsorption
sites (Haynes and Mokolobate 2001); (2) phytate-like
organic P in the compost may be satisfactorily mineralized
under high moisture content of the pellets; (3) inorganic P
inside of the pellets may be fixation-avoidable since it does
not contact with soil colloids; then (4) crop roots may efficiently absorb P from the compost granules.
(2) Compost-mixed compound fertilizer
In accordance with the Fertilizer Regulation Act (Act No. 127 of
1950), it had been prohibited to fortify compost with normal
fertilizers, such as nitrogenous mineral fertilizers. However, since
2014, a new official fertilizer specification, “compost-mixed
compound fertilizer,” was enacted, and now, it is possible to
register and manufacture fertilizers using composted manure
and/or composted food waste for fertilizer materials in the course
of business. For this granulated fertilizer, the amount of nutrients
are balanced, and the minimum amount of each nutrient is
guaranteed and clearly indicated, which makes it usable in the
same way as other compound fertilizers (Katoh 2017). Encouraging the increased use of this type of fertilizer in Japan is
expected to reduce the dependence on imported fertilizer
resources and reduce the cost of fertilizer in agriculture systems.
10.4.2 Nitrate Contamination of Groundwater
On Kyushu, welded tuff layers with a very low water permeability are mostly found on the edge of pyroclastic
deposit areas, and rainwater is ample (more than 2000 mm
of annual precipitation), and these geographical and meteorological conditions allow the storage of ample groundwater
in large parts of the island. Groundwater is extremely
important for domestic water supply in the southern part of
Kyushu. In particular, the Kumamoto region and the Miyakonojo basin region depend on groundwater for almost
100% of their domestic water supply, which supports populations of about 1 million and 240,000, respectively.
Some of the Nansei Islands, such as Miyako, Okinoerabu,
and Kikai Islands, are composed of limestones derived from
coral. Since there is a layer with a very low water permeability under the limestone layer, groundwater is retained in
the below ground part of those islands. Agriculture and daily
life in those islands are largely dependent on groundwater.
Despite the importance of groundwater in communities in
Kyushu and some of the Nansei Islands, nitrate (NO 3
− )
contamination of groundwater has long been a local environmental issue. For example, in Kumamoto Prefecture,
21% of 370 wells surveyed in 2012 contained NO 3
− concentrations higher than 10 mg N L
−1 (the water quality
standard in Japan) (Kumamoto Prefecture 2013). High NO 3
−
352
Y. Arakawa et al.