Agriculture Reference
In-Depth Information
Table 13.5 Annual cost, return, and wheat equivalent yield (WEY) in the NPK and NPK + FYM treatments in various
long-term experiments (Pathak et al. 2011 )
NPK treatment
NPK + FYM treatment
Cropping system
State
WEY a (Mt/ha)
Benefi t-cost ratio
WEY a (Mt/ha)
Benefi t-cost ratio
Rice-wheat
Meghalaya
4.6
1.6
7.1
2.4
Rice-wheat--jute
West Bengal
9.2
2.3
7.8
1.9
Rice-wheat
West Bengal
4.1
1.2
5.0
1.4
Rice-mustard-
sesame
West Bengal
6.6
1.6
8.1
1.9
Rice-berseem
West Bengal
3.4
1.2
3.9
1.3
Rice-wheat
Uttar Pradesh
7.6
2.6
7.6
2.5
Rice-wheat
Uttar Pradesh
7.1
2.4
6.2
2.0
Rice-wheat
Bihar
6.0
2.0
7.0
2.2
Rice-wheat
Uttar Pradesh
7.4
2.5
7.2
2.4
Rice-wheat
Uttarakhand
8.1
2.7
7.6
2.5
Rice-wheat
Punjab
6.5
2.8
7.6
3.1
Rice-wheat
Haryana
7.4
3.6
8.2
3.7
Rice-rice
Orissa
6.9
2.7
7.5
2.9
a WEY wheat equivalent yield
(NH 4 ) 2 SO 4 as N fertilizer to replace urea also
resulted in a 5-25 % decrease in CH 4 emissions.
As per Wassmann and Pathak ( 2007 ), the rela-
tive costs for mitigation through nitrifi cation
inhibitor were US$6.4, US$5.5, and US$9.8 per t
CO 2 e saved in Ilocos Norte province (Philippines),
Zhejiang province (China), and Haryana state
(India), respectively. In Ilocos Norte and
Zhejiang, the reduction potential was ca. 0.7 t
CO 2 e/ha, whereas this option only yields mar-
ginal emission savings (0.13 t CO 2 e/ha)
fl ood irrigation water for a period until the rice
shows symptoms of stress. It involves ridge and
furrow cultivation technology, where some
moisture still exists in the soil even after the toe
furrow is drained. It is essential to check when
the crop has used most of the available water. The
degree of soil cracking will depend on the soil
type and on the spatial distribution of the rice cul-
tivars. The cumulative evapotranspiration of the
crop varies from 77 to 100 mm during the time
water is removed depending on crop vigor and
soil types. The fi eld is then re-fl ooded as quickly
as possible. It is necessary to cover the soil surface
with water so that the plants start recovery. Water
depth then can be gradually increased to that
required for protection of the developing plant
canopy from damage with high temperatures dur-
ing anthesis. Mid-season drainage reduces meth-
ane emissions of paddy fi elds, with reductions
ranging from 7 to 95 % (Table 13.6 ).
However, rice is also a signifi cant anthropo-
genic source of N 2 O. Mid-season drainage or
reduced water use creates unsaturated soil condi-
tions, which may promote N 2 O production. Mid-
season drainage is an effective option for
mitigating net global warming potential although
15-20 % of the benefi t gained by decreasing
in
Haryana.
If incentives are given in terms of C credits for
mitigating global warming potential and subsi-
dies for reducing N loss, farmers will adopt these
technologies such as conservation tillage, soil
test-based N use, and more precise placement of
fertilizers on a large scale in South Asia (Ladha
et al. 2009 ).
13.1.5.2 Mid-Season Drainage
Mid-season drainage involves the removal of sur-
face fl ood water from the rice crop for about
7 days towards the end of tillering. It aerates the
soil, interfering with anaerobic conditions and
thereby interrupting CH 4 production. Mid-season
drainage of a rice crop involves withholding
 
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