Assessment of Organic Carbon Status in Indian Soils - Soil Carbon: Science, Management and Policy for Multiple Benefits - page 338

21 to 40% against a temperature increase
of 5°C. In the case of simulated water-limited
yields, the decrease varied from 10 to 36%
against a temperature increase of 3°C and
from 16 to 43% against a temperature in-
crease of 5°C. In all four places, Nagpur in
central India experienced a higher de-
crease in potential yields of 32 and 40%, as
well as in water-limited yields of 36 and
43% against a temperature increase of 3°C
and 5°C, respectively. Increased CO 2 con-
centration has a positive effect on cotton
crop yields ( Figs 28.4 and 28.5) . When
the CO 2 concentration increased from
369 ppm to 543 ppm, the increase in po-
tential and water-limited yields was in the
range of 4- 8% and 9- 16%, respectively.
If the CO 2 concentration increased from
369 ppm to 789 ppm, the increase in po-
tential yields varied from 7 to 11% and
from 12 to 24% in water-limited yields.
The utilization of increased CO 2 concen-
tration was relatively better in the case of
water-limited yields, due to soil moisture
consideration. In the simulated potential

yields, soil moisture is not considered. It was
observed that the interaction of increased
temperature and increased CO 2 concentra-
tion had a compensatory effect on cotton
yields, resulting in a smaller reduction in
potential yield and a non-significant re-
duction in water-limited yield.

Methane Production in Submerged
and Paddy Soils

Rice crop area and livestock population are
the two major sources of CH 4 emissions
from the agriculture sector. India is a major
rice growing country, with a very diverse
growing environment. There are several
studies on the estimation of methane emis-
sion from rice fields using various methods
( Table 28.6 ). Methane Campaign 1991 (MC-
1991) reported an annual methane emission
of 4.0 ± 2.0 Tg ( 1 Tg = 1012 g) for Indian
paddy soils. A state-wise study, conducted
in 1994, indicated a methane emission of

4200

4000

3800

3600

3400

CO 2 789 ppm

3200

3000

CO 2 543 ppm

2800

2600

2400 CO 2 369 ppm

2200

2000

0 1 2 3 4 5 6

Te mperature (°C)

Fig. 28.4. InfoCrop model output showing simulated potential yield of cotton crop in Akola, India. (From
Bhatttacharyya et al ., 2012.)