should also be evaluated. Furthermore, the application of
organic matter to rotated paddy fields could also increase
environmental loads such as greenhouse gas emissions and
N leaching (Takakai et al. 2017a, b). Consequently, the
careful management of organic matter application is
required.
6.4.3 Green Manure
The cultivation of green manure crops has been used as a
soil amendment for increasing soil fertility (Cherr et al.
2006). Legumes have been utilized as green manure crops in
agriculture because they can accumulate a large amount of
Fig. 6.20 Annual nitrogen
(N) flows and a budget in an
upland soybean field converted
from a rice paddy field (Three
years average, unit: g N m
−2 y
−1
).
N 2 O, nitrous oxide. N 2 emission
via denitrification was not
considered in this study. Modified
from Takakai et al. (2017a),
Copyright 2017, The Authors
licensed under CC BY 4.0.
Source Figure provided by
Fumiaki Takakai
Table 6.8 Nitrogen (N) flows
and budgets in soybean and
rice-cultivated field [unit: g N
m
−2 y
−1
, modified from Takakai
et al. (2017a)]
Upland soybean
Paddy rice
Input
Bulk N deposition
1.67
1.60
Irrigation
–
0.29
Seed (soybean) or Seedlings (rice)
0.40
0.12
N 2 fixation
16.7
2.0
Fertilizer
1.3
7.0
Total
20.1
11.1
Output
Harvested grain
22.2
6.51
Surface drainage
–
0.64
Leaching
7.45
3.94
N 2 O emission
0.17
0.01
NH 3 volatilization
ND
0.10
N 2 emission via denitrification
ND
2.19
Total
29.8
13.4
N budget
−9.6
−2.3
Positive and negative values indicated N input and output, respectively. The N budget was calculated by
subtracting N output from input. All values were expressed as annual value (three years average). N 2 fixation,
NH 3 volatilization, and N 2 emission via denitrification were estimated from literature value. NH 3 , ammonia;
N 2 , dinitrogen; N 2 O, nitrous oxide
212
H. Fujii et al.
organic matter to rotated paddy fields could also increase
environmental loads such as greenhouse gas emissions and
N leaching (Takakai et al. 2017a, b). Consequently, the
careful management of organic matter application is
required.
6.4.3 Green Manure
The cultivation of green manure crops has been used as a
soil amendment for increasing soil fertility (Cherr et al.
2006). Legumes have been utilized as green manure crops in
agriculture because they can accumulate a large amount of
Fig. 6.20 Annual nitrogen
(N) flows and a budget in an
upland soybean field converted
from a rice paddy field (Three
years average, unit: g N m
−2 y
−1
).
N 2 O, nitrous oxide. N 2 emission
via denitrification was not
considered in this study. Modified
from Takakai et al. (2017a),
Copyright 2017, The Authors
licensed under CC BY 4.0.
Source Figure provided by
Fumiaki Takakai
Table 6.8 Nitrogen (N) flows
and budgets in soybean and
rice-cultivated field [unit: g N
m
−2 y
−1
, modified from Takakai
et al. (2017a)]
Upland soybean
Paddy rice
Input
Bulk N deposition
1.67
1.60
Irrigation
–
0.29
Seed (soybean) or Seedlings (rice)
0.40
0.12
N 2 fixation
16.7
2.0
Fertilizer
1.3
7.0
Total
20.1
11.1
Output
Harvested grain
22.2
6.51
Surface drainage
–
0.64
Leaching
7.45
3.94
N 2 O emission
0.17
0.01
NH 3 volatilization
ND
0.10
N 2 emission via denitrification
ND
2.19
Total
29.8
13.4
N budget
−9.6
−2.3
Positive and negative values indicated N input and output, respectively. The N budget was calculated by
subtracting N output from input. All values were expressed as annual value (three years average). N 2 fixation,
NH 3 volatilization, and N 2 emission via denitrification were estimated from literature value. NH 3 , ammonia;
N 2 , dinitrogen; N 2 O, nitrous oxide
212
H. Fujii et al.