PII: S0045-6535(96)00223-~

Chemosphere. Vol. 33, No. 4. pp. 737-757, 1996 Copyright © 1996 Elsevier Science Ltd

Printed in Great Britain. All rights reserved 0045-6535/96 $15.00+0.00

METHANE BUDGET FROM PADDY FIELDS IN INDIA

D.C. Parashar'*, A.P. Mitra', Prabhat K. Gupta', J. RaP, R.C. Sharma', N. Singh', S. Koul', H.S. Rayb, S.N. Das b, K.M. Parida b, S.B. Rao b, S.P. Kanungo b, T. Ramasami °, B.U. Naiff, M. Swamf, G. Singh d, S.K. Gupta d, A.R. Singh d, B.K. Saikia e, A.K.S. Barua e, M. G. Pathal~, C.S.P. Iyer r, M. Gopalakrishnan t, P.V. Sand, S.N. Singh s, R. Banerjee t, N. Sethtmathan h, T.K. Adhya h, V.R. Rao h, P. Palit i, A.K. Salud, N.N. PurkaitJ, G.S. Clmturvedi ~, S.P. Sen ], M. Sen t, B. Sarkat a, A. Banild, B.H. Subbaraya m, S. Lal =, S. Venkatmmani =, G. LaP, A. Chaudhary*, and S.K. Sinha °.

a. National Physical Laboratory (NPL), Dr. K.S. Krishnan Road, New Delhi-110012, India. b. Regional Research Laboratory, Bhubaneswar (RRLB), Orissa- 751013. c. Central Leather Research Institute (CLRI), Adyar, Madras- 600020, Tamil Nadu. d. Central Fuel Research Institute (CFR1), Dhanbad-828108, Bihar. e. Regional Research Laboratory, Jorhat (RRLJ), Assam-785006. f. Regional Research Laboratory, Trivandrum (RRLT), Kerala-695019. g. National Botanical Research Institute (NBR.I), Rana Pratap Marg, Lucknow-226001, U . P . h . Central Rice Research Institute (CRRD, Cuttaek-753006, Orissa. i. Central Research Institute of Jute & Allied Fibres (CRIJAF), Barrackpore-743101, West Bengal. j. Institute of Radio Physics & Electronics (IRPE), Univ. of Calcutta, 92 Acharya Pmfulla Chandm Road, Calcutta, West Bengal-700009. k. Narendra Deo Univ. of Agriculture & Technology (NDUAT), Kumarganj, Faizabad-224229, U.P. 1. Kalyani University, Kalyani-741235, West Bengal. m. Physical Research Laboratory (PRL), Ahmedabad, Gujarat-380009. n. Indian Agriculture Research Institute (IARI), New Delhi-110012.

(Received in USA 13 January 1996; accepted 30 April 1996)

ABSTRACT

Results of national methane campaign launched in 1991 to assess methane budget from Indian paddy fields are reported. The campaign involved a number of scientific institutions and universities with National Physical Laboratory at Delhi operating as a nodal agency and covered most of the major rice growing regions of India. Methane emission rates ranged between -0.64 and 84.1 mg m'2h "1. The methane budget from Indian paddies has been estimated to be around 4.0 TgY l with a range between 2.7 to 5.4 TgY m. Copyright © 1996 Elsevier Science Ltd

1. INTRODUCTION

Increase In methane (CH4) concentration in the global troposphere is currently around 9.9 ppbv Y~ of

which nearly 60 percent is attributed to human activities (Houghton et al., 1990; Steele et al., 1992; Bolin et al.,

1994). Among the main anthropogenic sources, nearly 20% of the global methane budget from various sources

has been attributed to the rice paddy cultivation alone (Hogan et al., 1991). Asia has about 90 percent of the total

world rice harvested area out of which 60 percent falls in India and China. The estimated methane budget from

Indian paddy fields is of special significance as India has an area of about 42.2 Mha's (including multiple

cropping) under rice cultivation as compared to about 33.7 Mha's in China. On the basis of extrapolation of

measurements done in Europe and the U.S.A., the U.S. EPA attributed 37.8 Tg CH 4 y4 to Indian paddies, which

is an order of magnitude more than the earlier estimates for India of 3.0 TgY a based on field measurements at

737

738

a few rice growing regions in the country CtJ.S. EPA, 1990; Mitra, 1991; Parashar et al., 1991). Moreover, there

is significant variation in the methane emission rate depending upon soil parameters and water management

practices (Cicerone and Oremland, 1988; Sehutz et al., 1989; Saha et al., 1989; Yagi and Minami, 1990; Parashar

et al., 1991; Khalil et al., 1991; Parashar et al., 1993). In order to have a more reliable methane budget estimate

from Indian paddy fields, the 1991 methane campaign (MC91) was organised. It involved more than 15

organizations, Including various laboratories of the Council of Scientific & Industrial Research (CSIR), Institutes

of Indian Council of Agricultural Research (ICAR), and a number of universities. The measurements covered the

various rice ecosystems in the major rice-growing regions during wet season from June to November 1991.

2. METHODOLOGY AND SITE DESCRIPTION

The static box technique was used in the MC91 campaign for the measurement of methane emissions from

paddies (Mitra, 1992). This technique consists of fixing rectangular (30x50 cm 2 area) aluminium bases; mounted

with a U-shaped channel to hold water, at the measurement sites at two points within a few metres, well in

advance. The perspex box (30x50x76 cm 3 in size) with its open end rests in the channel. The water filled in the

channel isolates the air inside the perspex chamber from the outside atmosphere. Sampling kits as above were

used at all the sampling sites in the network except the deep water paddy fields where the perspex chamber was

60x40x143 em 3 with a base area of 60x40 em 2.

A battery-operated air circulation pump with a flow rate of 1.5 litres per minute, connected with polythene

tubes via a three-way stopcock, mixed the air inside the chamber and was also used to sample air (Figure 1). The

air was sucked from the top portion of the chamber by pump and pushed out near the bottom of the chamber to

ensure thorough mixing during the sampling period. Water level, paddy biomass volume, and the temperatures

inside the chamber were also measured during each sample collection for calculating the chamber air volume at

standard temperature and pressure (STP). The chamber was lifted and kept aside after 30 minutes. Air sampling

from the chamber was done at intervals of 0, 15, and 30 minutes, and ambient air was taken once a week at about

10:00 hours and 16:00 hours, giving 14 samples (8 flux data points). The chamber was tested for leakage at lower

(-5 ppmv) and higher (-50 ppmv) concentrations of CH4 maintained during simulated experiments up to 90

minutes with a 5-minute sampling time interval.

The air samples brought to the laboratory were analysed by a gas chromatograph (GC) equipped with flame

ionization detector (FID) and a column of Molecular Sieve-5A. GC calibration for CH 4 was done using secondary

standards, viz., 1.94 ppmv CH4 standard in air, 4.4 ppmv and 10.9 ppmv CH4 standards in nitrogen, prepared at

NPL. A primary standard of 1 ppmv CH4 in nitrogen from M/s Mathesons Gas Products, USA, was used for

calibrating the above secondary standards. The methane flux was calculated from the temporal increase of the

methane mixing ratios inside the box using the equation:

Oq

..< O.,

P

POLY

THEN

E TU

BE

FITT

ING

PER

SPEX

BO

X o

j \

' TH

ERM

OM

ETER

~

SO

IL

THER

MO

MET

ER

, "

~ -.i

~r

T~

A

;~"3

- W

AY V

ALVE

OCK

r"-]

~TEF

LON

_

r AMPL

ING

BAG

Expe

rimen

tal

arra

ngem

ent

for

met

hane

eff

lux

mea

sure

men

t.

740

CH+ Flux(F) (rag m-2h -1) = BVsa v × Ccn' x 16 x 1000 × 60

I0 + x22400 xAxt

where

BVsw (Box Air Volume in cc at STP) = BV x B.P. x 273 (273 +T) x760

Box air volume, BV -- [(H-h)LW - Biomass volume inside box]; H = box height; h = water level above channel;

L = box length; W = box Width in cm; B.P. = barometric pressure (ram Hg); T = box air temperature at the time

of sampling in * C; Co~ = change in CH+ concentration in ppmv from 0 minute sampling to the t minute

sampling; and A = paddy area covered by the box in m 2.

The accuracy and comparability of CI-I4 concentration values were established by calibration and

intercomparison between the National Physical Laboratory (NPL) and other network stations. The absolute

calibration comparability at the international level was established by exchanging samples with the Division of

Atmospheric Physics, CSIRO, Australia, the National Institute of Agro-Environment Sciences (NIAES), Tsukuba,

Japan, Max Plank Institute of Chemistry (MPI), Mainz, Germany, and the NPL, New Delhi.

The MC91 network (Figure 2) sites, 34 in number, were located at RRL farms Jorhat (Assam), Garagacha

Garia, Raghabpur Purulia, Charsharati Kalyani Nadia, North farms Devoke and Koirapur Barrackpore 24 Pergana

(West Bengal), Dehri-on-sone (Bihar), CRRI farms Cuttack (Orissa), Pudupakkam Chenglepet (Tamil Nadu),

Pappanamcode Trivandrum (Kemla), Andawa Allahabad and NDUAT farms Kumarganj Faizabad (Uttar Pradesh)

and IARI farms Delhi. The paddy soil characteristics for the above sites are given in Table 1.

The total areas of paddies harvested annually in India were classified (see Table 2) for CH4 emission

extrapolation and its budget estimate in four regions (east, south, north and west), for continuously flooded or

irrigated, intermittently flooded or rainfed, deep water, and upland paddy water ecosystem categories 0RRI, 1984;

Handbook on Cultivars, 1985; IRRI, 1986; Gupta and Toole, 1986; Ministry of Agriculture, 1990; OECD, 1991;

IRRI, 1993; Bolin, 1995). There are no published data available yet for the area under intermittently flooded fields

based on actual survey out of both rainfed and irrigated areas. However, some information about the intermittently

flooded areas is given for inventory purposes to estimate methane from rice paddies (Bolin, 1995). Many shallow

rainfed areas, representing about 35% of all ricelands in south and southeast Asia, have moisture sufficiency

comparable to that of irrigated lands; other rainfed shallow areas are so prone to water stress that they may be

comparable to upland areas (IRRI, 1984). These rainfed areas often experience dry and flood cycles according

to the availability of rainwater and therefore have been termed as intermittently flooded areas by IPCC (Bolin,

1995).

7 4 1

R I C E "'-" 1991 ~ethane Campaign Network

/ , C " : . ~ l . t ' " . . f aizw~aa I - . J ' ~ . . ' " -~.-':',J~.~.'.." : l - - - - - 7 . / - ~ " ~-

." - " + " ~ ' J ~ X " ~ Q ' [ ' ~ q ~ 7 " ~ - ~'~ e " ' r / ¢ C~ I " ~ " " " "-" " ' /q"-"- ~ • ~" .A'~.-" . , t " ~

t . ~ . % . _ . . . , , , , ; , . : ~ .,," .~ ..., ; ~ . ~ ~ ~ - , . . . . .

, - , . - , ~ ' - ' ~ t -~ ¢ I (~ : ' - ! .? .~ . - : . ' ~ ' : ~ : : . : y ~ r " . : .' . . . . - , -" • " - . . . . . . . . . .~ .~ / . . _ : ~-s ~ , • $ ~ " . -~:" l ' ~ . : " - . ' . " . " :.~ - . ' ~ . ~ . W

' : - - : . ' ~ * - : : ~ - - : ; ~ : :~;:_-:.:~'~-"~ 2 h / ......... x lr~. ~ ~. , " - . . . ~ . ~ , . . . . . , r :. : . . . . ~ .~ .:-~

~ .---- .-- - , - i " ~--: ::-~ ? : . ~ ".;:;-. ~ Y • . o . . . . . . ~ - g - •

d - . . ; , . , . . . . . . . . . . . ; ; - \ I ~ . " , . :'- " , ' ; ' : - " -' ~ t ' : : . ~ " " . - . , / "'." . . . . " " " . - I ~ " G a ' i a , K r v l i a , K o o d O i h a r , I

"-'- • " # 4"" X" " . ' : - " : "" '-: :

::" . t y- . . . . ( - " . . . :'..'.~ :..7-.. "" Midnapur, Barrad~ J

y . " . . . , . -'-.: I . ~" ~ t~;~i

\: :::-. C i i::..~: i ~ ~- ~i~t" ~,~,, ~-.:-... ",e.-:. -,".:.~3 ~ 4. Assam .:::" , . . . : - 7 ~ r s | ~ v ~ s. ~ t ~ a ,

7. Tamil Nadu ~ ~ ' ~ 8. Kera la

• N e t w o r k S t a t i o n s

F i g u r e 2 . M e t h a n e f l u x m e a s u r e m e n t c a m p a i g n n e t w o r k s t a t i o n s i n m a j o r r i c e g r o w i n g a r e a s o f I n d i a d u r i n g

1 9 9 1 .

Tab

le 1

. P

addy

soi

l ch

arac

teri

stic

s of

MC

91 N

etw

ork

site

s

.Ix

tO

Sr.

No.

So

il T

extu

re

Net

wor

k St

atio

n\Si

tes

1. N

PL

, N

ew D

elhi

, IA

RI

Farm

s S

andy

loa

m

2. C

FR

I, D

hanb

ad,

Bih

ar

a. A

ndaw

a, A

id.

San

dy l

oam

b.

Deh

ri-o

n-so

ne,

Bih

ar

San

dy l

oam

3. C

LR

I, T

amil

Nad

u, P

udup

akka

m,

San

dy l

oam

M

adra

s

4. N

BR

I, L

uckn

ow,

U.P

., F

aiza

bad

Silt

-cla

y

5. C

RR

I, C

utta

ck,

Ori

ssa,

CR

RI

Far

ms

San

dy-c

lay

6. R

RL

Bhu

bane

shw

ar,

CR

RI

Cut

tack

S

andy

-cla

y fa

rms

7. R

RL

, Jo

rhat

, A

ssam

, R

RL

, Jo

rhat

Far

ms

Cla

y lo

am

8. R

RL

, T

riva

ndru

m,

Ker

ala,

S

andy

cla

y P

appa

nam

code

Fie

lds

9. C

RIJ

AF

, B

arra

ckpo

re,

Wes

t B

enga

l a.

Nor

th F

arm

s C

lay

b. D

evok

e C

lay

loam

c.

Koi

rapu

r C

lay

loam

10.

Kal

yani

Uni

vers

ity,

Nad

ia,

W.B

., S

andy

loa

m

Cha

rsha

rati

11.

IRPE

, U

nivs

ity

of C

alcu

tta

a. G

arag

acha

, G

aria

b.

Rag

habp

ur,

Puru

lia

--

pH

Org

anic

C

arbo

n (%

)

8.3

0.6

7.2

0.48

5.

6 1.

56

0.8

--

8.2

0.27

6.2

0.6

7.2

0.6

4.7

1.1

6.5

1.46

7.0

0.22

6.

8 0.

32

6.8

0.32

7.7

0.66

7.8

1.12

5.

0 --

Ele

c. C

ond.

(m

mho

cm

-~)

C.E

.C.

(me/

100g

) P

erce

ntag

e

San

d Si

lt

0.49

15

.2

51.5

23

.8

0.18

10

.4

- -

0.10

20

.15

- --

3.45

-

- -

0.35

-

11.0

71

.0

1.2

18.6

51

.0

22.0

1.2

18.6

51

.0

22.0

M --

14.5

-

--

N

Cla

y

24.7

M 18

.0

27.0

27.0

--

u --

Table 2. Indian paddy cultivation area (x 10 ° ha) distribution.

743

Region/State Total Area Cont. Hooded Int. Hooded Deepwater Upland (Irrigated) (Rainf~l)

Eastern Region West Bengal 5.610 1.593 2.457 0.677 0.883 Bihar 5.330 1.892 2.235 0.672 0.531 Orissa 4.390 1.440 2.109 0.150 0.691 Assam 2.430 0.525 1.590 0.100 0.215 N.E. States 0.823 0.244 0.219 0.040 0.320

Total Area 18.583 5.694 8.610 1.639 2.640

Southern Region Andhra Pradesh 4.190 2.705 1.245 0.240 - Tamil Nadu 2.010 1.417 0.593 . . . . Kamataka 1.180 0.710 . . . . 0.470 Kerala 0.570 0.238 0.017 -- 0.315 Pondicharry 0.025 -- 0.025 . . . . Andamans 0.012 -- 0.012 - --

Total Area 7.987 5.070 1.892 0.240 O. 785

Northam Region Uttar Prardesh 5.360 0.458 3.174 0.233 0.495 Punjab 1.910 1.910 . . . . . Haryana 0.620 0.620 . . . . . . Delhi 0.003 0.003 . . . . .

J & K 0.276 Himachal Pradesh 0.093 Sikkim 0.015

Total Area 8.277 3.991 3.174 0.233

0.384

0.879

Western Region Madhya Pradesh 5.040 0.912 1

I 3.377 0.322 1.669 Maharashtra 1.520 0.280 1

Gujrat 0.600 0.390 0.210 - - Dadra N.H. 0.011 - 0.011 . . . . Rajasthan 0.160 0.160 . . . . . . Goa, Daman & Diu 0.054 - 0.054 - -

Total Area Z385 1.742 3.652 0.322 1.669

GRAND TOTAL 42.232 16.497 17.328 2.434 5.973

744

3. RESULTS AND DISCUSSION

Results of mean CH4 flux values for each network site over the entire measurement period in the cropping

season are shown in Figures 3, 4, and 5. Diurnal variations of C H 4 flux data during the cropping season for

continuously flooded and intermittently flooded sites are shown in Figure 6. The duration of the cropping period,

the CI-I4 flux measurement period, the paddy variety, and the seasonal integrated CH4 flux (SIF) for each network

site are given in Table 3. Data show that CH4 flux values range between -0.64 and 84.1 mg rn2h 1. Paddies grown

in irrigated or continuously flooded areas (Figure 3a and 3b) and deep water regime categories (Figure 5) have

a much higher CH4 flux compared to rainfed areas where continuous water flooding has not been maintained

(Figure 4a and 4b). Upland paddy areas were not studied because they are assumed to emit negligible CH4 (Hogan

and Braatz, 1990; Mitra, 1991; Bolin, 1995). The observed negative CH4 flux at some points of the cropping

season (Figure 4a) in intermittently flooded fields indicates that these fields are a sink. It may be because of

frequent drying up of the soil. The CH4 is oxidized due to change from anaerobic to aerobic soil conditions with

the diffusion of atmospheric oxygen into it (Keller et al., 1990). Diurnal variations in low CH4 flux Delhi sites

(Figure 6a) did not clearly show any trend as compared to the irrigated or continuously flooded site of CRRI farm

paddy fields in cuttack having higher CH4 flux, wherein (Figure 6b) it clearly indicates that emissions are greater

during the afternoon, whereas it tends to decrease from late evening to early morning. This can be attributed to

high soil temperatures in the afternoon.

The seasonal CH4 flux data at each site vary in both the channels having the same paddy variety, age and

water management practices. Therefore, the mean seasonal integrated CH4 flux (SIF) and its range were worked

out for each network site by taking the daily mean of the flux data obtained once during every week and

integrating it over the whole cropping season. Data have been extrapolated for gap periods, if any, in the cropping

season from transplantation to harvest stage, to estimate the total seasonal flux (SIF). Standard deviations from

the mean flux for one day's data every week over the cropping season are used to obtain the maximum and

minimum ranges of SIF. The SIF and its range so obtained for each network site (Table 3) were used in various

paddy cultivation ecosystems classified for estimating the CH4 budget for India (Table 4). SIF for states/union

territories not having any network station have been estimated, on the basis of assuming similar agroclimatic

conditions, by applying the mean SIF of the network stations located around that region.

The mean CH 4 SIF values obtained from five stations located at Garia, Purulia, Kalyani, North farm and

Devoke in Barrackpore were applied to the entire area in irrigated or continuously flooded category In West

Bengal (WB). The SIF from WB and Orissa stations was applied for Bihar and northern region irrigated areas of

Uttar Pradesh, Punjab, Haryana, and Delhi. The mean SIF from 3 sites in Orissa was used for paddy areas in

Orissa under this category. The SIF from the station located in Jorhat was applied to Assam and N.E. (North East)

states. The SIF for Tamil Nadu station was used for the entire southern region paddy areas of Andhra Pradesh,

Tamil Nadu, Kerala, and Kamataka. Similarly, the mean SIF of Orissa and Tamil Nadu stations was applied to

the entire western region irrigated areas of Madhya Pradesh, Maharashtra, Gujarat and Rajasthan. States, viz.,

Pondicharry, Andamans, Jammu & Kashmir, Himachal Pradesh, Sikkim, Goa Daman & Diu, and Dadar N.H., do

745

CH4 F l u x ( m g l m 2 , h ) 18

16

1,4

12

10

8

6

4

2

0

,r~

fl

I

, t

i//

L V \ t t l t't

_./ ~ ", ir', t .l~ \ ! ;l t I

z ~i \',, ~ ,,~

~ ~ , ~ . I I I I

20 40 60 80

Days Alter T r a n s p l a n l o l l o n

,o

I

0 lO0 120

:~ P u r u l l a " ( ~ N a d l a 0 D e v o k e Bkp.

A RRLB X CLRIM

Figure 3a. Seasonal methane flux from irrigated (continuously flooded) paddy water regime areas in Raghabpur Purulia (- * -) WB, Charsharati Kalyani Nadia (- [] -) WB, Devoke Barrackpore (- 0 -) WB, Cuttack RRLB (- a -) Orissa and Pudupakkam Madras (- _~ -) Tamil Nadu.

50

40

30

E]•,

i, i

20

lO

CH4 Flux (mg/m2,h) N.Farm

I !

0 20 40 120

/

; X

I \

60 80 100

Days After Transp lan tc~lon

~r G o r l a • RRLJ D N , F a r m B k p .

~- C R R I C l 0 C R R l C 2

70

60

50

40

30

20

746

0

Figure 3b. Seasonal methane flux from irrigated (continuously flooded) paddy water regime areas in Garagacha Garia (- g -) WB, RRL farms Jorhat (- * -) Assam, North farm Barrackpore (- [] -) 24 Pargana North WB, CRRI Cuttack farms plot 1 (- A -) Orissa and CRRI Cuttack farms plot 2 (- 0 -) Orissa.

747

CH4 F l u x ( m g / m 2 . h ) 1.2-r

0,8

0.6

0,4

0.2

0

-0 ,2

-0,4

..k..

0 140

[]

I I I ! I I

20 40 60 80 100 120

Days After Transplantation

A i d . 0 I A R I - C I r l . ' • I A R I - N 6 0

I A R I - N I 2 0 × I A R I - W T C

Figure 4a. Seasonal methane flux from rainfed (intermittently flooded) paddy water regime areas in Andawa Allahabad (- • -) Uttar Pradesh, IARI farms paddy plots control (- 0 -), N60 (- * -), NI20 (- I--I -) and WTC (- x -) of Delhi.

748

25

20

15

10

5

0

CH4 Flux ( m g / m 2 , h ) NBRIF

• 0 0 0 20 140

Days After

4 / ~\

! \ i i

"....

I I I I ~1

40 60 80 100 120

T r a n s p l a n t a t i o n

I 0 Dehri on Sane I RRLT ~ NBRIF J

Figure 4b. Seasonal methane flux from rainfed (intermittently flooded) paddy water regime areas in Dehri-on-sone (- 0 -) Rohtas Bihar, Pappanameode Trivandrum (- + -) Kerala and NDUAT farms Faizabab (- * -) Uttar Pradesh.

25

20

15

10

5

0 !

0 81 gO

OH4 Flux (mg/m2.h)

749

I I I I I I I I I

4 11 18 2@ 82 39 5,3 60 67

Days After Transplantation

Kolrapur Bkp. I Figure 5. Seasonal methane flux from deep water paddy regime areas in Koirapur Barrackpore (- * -) WB.

750

CH4 Flux (mgtm2.h) 2.5

1,5

_

0.5

0

-0 .5

15

/ \ / \ :

/ i ,,

..': '~ " '4 ..: \ ,.~ \~ y/ ........... .,.. ,,

, ~ . . /' ,_

, , t , , I , , I , , I ,

24 og 18 03

Time (hrs)

0 SEP-Otrl. ~ SE P - N 1 2 0

13 O O T - O t r l . X O O T - N 1 2 0

Figure 6a. Diurnal variations in methane flux from IARI farms paddy (Variety PUSA-615) plots of Control and N120 during 12-14 September (SEP) and 10-12 October (OCT) 1991.

751

20

15

10

5

0

CH4 Flux (mg/m2,h)

7

/ •

/ ~,

/ ~ / .,,,

/ \ t~ ! / ,.,.

, / \ :

o % \ ',\. /

08 11 14 17 20 23 02 05 08 11 14

T i m e ( h r s )

~ CRRI-SEP D GRRI-OCT 0 CRRI-NOV ]

Figure 6b. Diurnal variations in methane flux from CRRI Cut'tack farms paddy during 23-24 September [CRRI- SEP (- * -), Variety: Ratna], 3-4 October [CRRI-OCT(- [] -) Variety: IR-36] and 25-26 November [CRRI-NOV(- 0 -) Variety: Gayatri-CRl018] 1991.

Tab

le 3

. P

addy

crop

ping

and

CH

4 fl

ux m

easu

rem

ent

peri

ods

at M

C91

Net

wor

k St

atio

ns a

long

with

pad

dy v

arie

ty a

nd s

easo

nal

inte

grat

ed f

lux.

I'

0

Sr.

No.

C

ropp

ing

Peri

od

Mea

sure

men

t Pe

riod

Day

s Pa

ddy

Var

iety

Se

ason

al I

nteg

rate

d Fl

ux o

f C

H4

Stat

ion/

Site

s (D

ays)

D

ates

(S

IF i

n g

m -2

)

Max

imum

M

ean

Min

imum

1. R

RL

Jor

hat,

Ass

am/

106

RR

LJ

Farm

s

2. C

RR

I C

utta

ck, O

riss

a/

Cll

d

114

A12

bc

110

3. R

RI

Bhu

bane

shw

ar,

Ori

ssa/

90

C

RR

I Fa

rms

4. C

RIJ

AF

Bar

rack

pore

, W

B/

Dev

oke

110

N.

Farm

13

0 K

oira

pur

130

5. K

alya

ni U

niv.

, N

adia

WB

/ 11

0 C

hars

hara

ti

6. R

RL

Mad

ras,

Tam

il N

adu/

79

* Pu

dupa

kkam

7. R

RL

Tri

vand

rum

, K

eral

a]

73

Papp

anam

code

8. N

BR

I L

uckn

ow,

Utta

r 11

0 Pr

ades

h/

ND

UA

T,

Faiz

abad

9. C

FRI

Dha

nbad

, Bih

ar/

105

Deh

ri-o

n-So

ne

10. C

FRI-

Alla

haba

d, U

.P.

119

And

awa

20.8

to

28.1

1.91

10

1 M

ahsu

ri

62

46

32

20.8

to

19.1

0.91

61

R

atna

15

13

.2

11

20.8

to

19.1

0.91

61

A

rmad

a 10

8.

2 7

21.8

to

23.1

0.91

64

IR

-36

21

14

7

7.8

to 9

.10.

91

58

Rat

na

2.2

1.8

1 2.

8 to

11.

10.9

1 64

Pa

nkaj

80

63

47

5.

8 to

21.

10.9

1 78

D

ahar

Nag

ra

26

19

13

16.8

to

1.10

.91

53

Mas

uri

16

10.8

7

23.8

to

29.1

0.91

74

B

PT-3

402

15

11

7

7.8

to 1

8.09

.91

43

Che

ena

14

9 4

20.8

to

10.1

0.91

52

Sa

rju-

52

2.8

2 1.

3

17.9

to

24.1

1.91

69

M

ansu

ri

28

22

15

21.7

to

10.1

1.91

11

3 M

inar

0.

9 0.

52

0.15

Sr.

No.

St

atio

n/Si

tes

Cro

ppin

g Pe

riod

(D

ays)

M

easu

rem

ent

Dat

es

Peri

od D

ays

Padd

y V

arie

ty

Seas

onal

Inte

grat

ed F

lux

of C

I-I 4

(SIF

in

g m

a)

Max

imum

M

ean

Min

imum

11. N

PL-I

AR

I Del

hi/

IAR

I-C

trl.

118

IAR

I-N

60

118

IAR

I-N

I20

118

IAR

I-W

TC

11

8

12. I

RPE

, Uni

v. o

f C

alcu

tta,

Cal

cutta

, W.B

./ G

arag

acha

Gar

ia

100

Rag

habp

ur

85

18.7

to 1

.11.

91

18.7

to 1

.11.

91

18.7

to 1

.11.

91

18.7

to 1

.11.

91

8.9

to 2

4.11

.91

20.9

to 1

4.11

.91

106

Pusa

-615

0.

3 0.

16

0.08

10

6 Pu

sa-6

15

0.07

0.

06

0.05

10

6 Pu

sa-6

15

0.76

0.

58

0.45

10

6 Pu

sa-6

15

0.07

0.

06

0.05

78

Fine

40

29

18

56

Fi

ne

15

11

7

* M

easu

rem

ents

dis

cont

inue

d du

e to

cyc

loni

c de

stru

ctio

n.

t.h

Tab

le 4

. M

etha

ne B

udge

t E

stim

ates

fro

m I

ndia

n P

addy

Fie

lds

Are

as/R

egio

ns/S

tate

s

1. E

AST

ER

N R

EG

ION

a)

Wes

t B

enga

l

b) B

ihar

c)

OrL

~sa

d) A

ssam

e)

N.E

. St

ates

Padd

y C

ultiv

atio

n A

rea

(Mha

) (I

rr.

or C

ont.

Fld.

)

Inte

grat

ed S

easo

nal

CH

4 Fl

ux

(SIF

edm

2)

Max

M

ean

Min

.

Tot

al M

etha

ne E

mis

sion

fig

/Y)

Max

. M

ean

Min

.

1.59

3 30

.6

23.1

16

0.

49

0.37

0.

26

1.89

2 24

.9

18.9

13

.1

0.47

0.

36

0.25

1.

440

15.3

11

.8

8.3

0.22

0.

17

0.12

0.

525

62

46

32

0.33

0.

24

0.17

0.

244

62

46

32

0.15

0.

11

0.08

15

11

7 0.

62

0.45

15

11

7 0.

14

0.10

24.9

18

.9

13.1

1.

03

0.75

15.3

11

.6

8 0.

27

0.20

26

19

13

5.9

4.3

2.6

NIL

I I

2. S

OU

TH

ER

N R

EG

ION

a)

And

lara

Pra

desh

2.

705

1 b)

Tam

il N

adu

1.41

7 I

c) K

eral

a 0.

238

1 cO

Kam

atak

a 0.

710

1

3. N

OR

TH

ER

N R

EG

ION

a)

Utta

rpra

de,s

h 1.

458

I b)

Pun

jab

1.91

0 1

c) Har

yana

0.

620

d) Delhi

0.003

1

4. W

EST

ER

N R

EG

ION

a)

Mad

hya

Prad

esh

0.91

2 1

b) M

ahar

asht

ra

0.28

0 1

c) G

ujar

at

0.39

0 1

d) R

aja~

.han

0.160

1

TOTA

L 16.497

5. All dee

p water areas

2.434

6. All rainfed or inter-

17.328

mit

tent

ly i

rrig

ated

are

as

7.

Upl

and

area

s 5.

973

GR

AN

D T

OT

AL

42

.232

3.72

2.

83

0.63

0.

46

1.02

0.

75

5.37

[

Ref

eren

ce S

tati

ons

for

Ext

rapo

lati

ons

NIL

4.04

[

(Tab

le 2

)

Ave

. of

Gar

ia,

Puru

lia,

Kal

yani

, N

. Fa

rm,

and

Dev

oke

Ave

. of

W.B

. &

Ori

ssa

Site

s A

ve.

of R

RL

B,

CR

RIC

I, C

RR

IC2

RR

LJ

RR

LJ

2.67

0.29

C

LR

IM

0.07

C

LR

IM

0.52

A

ve.

of W

.B.

& O

riss

a St

n.

0.14

A

ve.

of O

riss

a &

CL

RIM

Sin

.

1.90

0.32

K

oira

pur

(W.B

.)

0.45

A

ve.

of D

ehri

-on-

Sone

, RR

LT

, N

BR

IF,

Aid

. &

4 s

ites

of D

elhi

IPC

C,

1992

755

not have any paddy cultivation in the irrigated category. East India receives maximum rainfall in the Indian sub-

continent, and with irrigation it leads to longer inundation periods of the paddy fields, which helps in generating

the sustainable anaerobic environment for methanogenesis and explains observed high CI-L flux. The range of SIF

in the continuously flooded or irrigated category varies between 7 to 62 gm a, and its budget estimate has a mean

of 2.83 TgY 1 with a range between 1.9 to 3.72 TgY m (Table 4). The large ranges of SIF can be due to varying

hydrological conditions from place to place not only in different sustainable flooding depth but in the flooding

duration as well, apart from low or high soil organic carbon, soil temperature, and paddy cultivar.

The Koirapore site in Barrackpore WB (Figure 5), which has a water depth of the order of 50 cm,

represents the paddy water regime category of semi-deep (30 to 50 cms)/deep water (>50 cms) (IRRI, 1994). The

SIF value of 19 gm z with a range 13 to 26 gm "z from this site was applied to all Indian deep water paddy areas.

This has led to its CI-~ budget estimate of 0.46 TgY 1 with a range between 0.32 and 0.63 TgY l for the deep and

semi-deep water regime.

The Andawa paddy field of Allahabad (Aid.) and NDUAT farms paddy fields of Faizabad (NBRIF) in UP,

Dehri-on-sone in Bihar, Pappanamcode Trivandrum (RRLT) in Kerala, and four IARI farm paddy field sites (Ctrl.,

N60, N120 and WTC) in Delhi represent intermittently flooded or rainfed areas because of non-continuous

flooding of these fields (Figure 4a and 4b). Three of the four IARI farm sites in Delhi have nitrogen fertilizer

treatment as Urea @ 0, 60 and 120 Kg Ha~(Ctd., N60 and N120), and the fourth site at Water Technology Centre

(WTC) paddy plots is without any fertilizer. CH4 fluxes were low in these four sites including negative fluxes

at some stages in the cropping season (Figure 4a). The SIF for the Bihar site was calculated by extrapolating the

CH 4 emission up to the date of transplantation (DOT) from the measurement period of 67 to 135 DAT (by

doubling the integrated emission for measured half cropping period, which includes the pre-flowering stage to the

harvest stage) and may be on the higher side. The mean SIF of all intermittently flooded stations were applied

in estimation of the CH4 budget from paddy fields under rainfed or intermittently flooded categories (Table 4).

The range of SIF under this paddy water regime is between 2.6 to 5.9 grn z, and the CH 4 budget estimate ranges

between 0.45 and 1.02 TgY -~.

Previous studies in Texas and California in USA, in Spain, and in Italy, etc., have ranges of SIF values

in continuously flooded fields within 10-50 gm "2 and are comparable to our measurements (Cicerone and Shetter,

1981; Holzapfel-Pschom and Seiler, 1986; Schutz et al., 1989; Sass et al., 1990). Uncertainities in the budget

estimates come from the lack of a sufficient database on CH4 flux from different paddy ecosystems and also from

differences in classification methodology of rice land areas. Accurate statistics on paddy cultivation area

distribution based on flooding duration and depth, which is an important parameter among the various factors

influencing methane production and emission, need to be developed.

4. CONCLUSIONS

The total CH4 budget worked out for different Indian paddy cultivation water regimes, viz., continuously

flooded (irrigated), intermittently flooded (rainfed), and deep water categories, is between 2.7 to 5.4 TgY ~ with

a mean of around 4.0 TgY ~, close to our earlier estimates of 3.0 TgY ~. This value is an order of magnitude low

756

as reported earlier by IPCC, and the consequence of these low values is that the global CI-L emissions from

paddies are probably lower than the mean value of 60 TgY ~ used in the IPCC 1992 update.

ACKNOWLEDGEMENTS

The authors are grateful to Dr. E.S.R. Gopal, Director, NPL, and Dr. K. Lal, head material characterization

division, NPL, for their keen interest in this work. The financial support from the Ministry of Environment &

Forests (MoEF), the Government of India, and technical help from the National Council of Science Museums,

Calcutta, are gratefully acknowledged. Kind help for intercomparison and calibration from Dr. P.J. Crutzen, Max

Plank institute of chemistry, Mainz, Germany, Dr. K. Minami, NIAES, Tsukuba, Japan, and Dr. P. Fraser and Dr.

P. Steele, CSIRO, Australia, is gratefully acknowledged. The benefit of discussions with Prof. M.A.K. Khalil,

Department of Physics, Portland State University, Oregon, USA, is gratefully acknowledged.

REFERENCES

Bolin, B., S.J. Houghton, and L.G.M. Filho (1994), Radiative Forcing of Climate Change: The 1994 report of the Scientific Assessment Working Group oflPCC - Summary for Policymakers, IPCC-WMO/UNEP, Geneva., p. 18.

Bolin, B. (1995), IPCC Guidelines for National Greenhouse Gas Inventories: Reference Manual, OECD Environment Directorate, Paris, France, p. 4.51-4.59.

Central Seed Committee publication (1985), Handbook on Cultivars (Dept. of Agr. Cooperation, Ministry of Agr. & Rural Development, New Delhi), p. 8-11.

Cicerone, R.J., and J.D. Shetter (1981), Sources of atmospheric methane: Measurements in rice paddies and a discussion, J. Geophys. Res., 86, 7203-7209.

Cicerone, R.J., and R.S. Oremland (1988), Biogeochemical aspects of atmospheric methane, Global Biogeochemical Cycles, 2(4), 299-327.

Environmental Protection Agency (1990), Methane Emissions and Opportunities for Control, EPA[40019-90]O07, US EPA, Washington DC.

Gupta, P.C., and J.C.O. Toole (1986), Upland Rice: A Global Perspective, IRRI, Phillipines, p. 2-5.

Hogan, K., and B. Braatz (1990), Sustainable Rice Productivity and Methane Reduction: Research Plan (EPA Was :hington D.C.), p. 12-14.

Hogan, K., J.S. Hoffman, and A.M. Thompson (1991), Methane on the Greenhouse Agenda, Nature 354, 181-182.

Holzapfel-Pschom, A., and W. Seiler (1986), Methane emission during a cultivation period from an Italian rice paddy,./. Geophys. Res., 91, 11803-11814.

Houghton, J.T., G.J. Jenkins, and J.J. Ephraums (ed.) (1990), Climate Change: The IPCC Scientific Assessment, Cambridge University Press, p. 44-56.

IRRI (1984), Terminology for Rice Growing Environments, Published by International Rice Research Institute, Los Banos, Laguna, Manila, Philippines, p. 5-16.

IRRI (1986), Progress in Rainfed Lowland Rice, published by International Rice Research Institute, Los Banos,

757

Philippines, p. 4, 28, 124, and 398.

IRRI Rice Almanac (1993), Published by International Rice Research Institute, Los Banos, Philippines, p. 55-57.

Keller, M., M.E. Mitre, and R.F. Stallard (1990), Consumption of atmospheric methane in soils of central Panama: Effects of agricultural development, Global Biogeochemical Cycles, 4, 21-27.

Khalil, M.A.K., R.A. Rasmussen, M.-X. Wang, and L. Ren (1991), Methane emissions from rice fields in China, Environ. Sci. Technol., 25(5), 979-981.

Ministry of Agriculture (1990), All India Final Estimates of Rice: 1989-1990.

Mitra, A.P. (ed.) (1991), Global Change: Greenhouse Gas Emissions in India - A Preliminary Report, No.l, PID CSIR, p. 18-21.

Mitra, A.P. (Ed.) (1992), Global Change: Greenhouse Gas Emissions in India - 1991 Methane Campaign, No.2, PID CSIR, p. 11-14.

OECD final report (1991), Estimation of Green House Gases and Sinks, p. 5-36 and 5-43.

Parashar, D.C., J. Rai, Prabhat K. Gupta, and N. Singh (1991), Parameters affecting methane emission from paddy fields, Indian J. Radio & Space Phys., 20, 12-17.

Parashar, D.C., Prabhat K. Gupta, J. Rai, R.C. Sharma, and N. Singh (1993), Effect of soil tempemaxre on methane emission from paddy fields, Chemosphere 26, 247-250.

Saha, A.K., J. Rai, V. Raman, R.C. Sharma, D.C. Parashar, S.P. Sen, and B. Sarkar (1989), Methane emission from inundated fields in a monsoon region, Indian J. Radio & Space Phys. 18, 215-217.

Sass, R.L., F.M. Fisher, P.A. Harcombe, and F.T. Turner (1990), Methane production and emission in a Texas rice field, Global Biogeochemical Cycles, 4, 47-68.

Schutz, H., A. Holzapfel-Pschorn, R. Conrad, H. Rennenberg, and W. Seiler (1989), A three year continuous record on the influence of daytime, season and fertilizer treatment on methane emission rates from an Italian rice paddy field, J. Geophys. Res., 94, 405-416.

Steele, L.P., E.J. Dlugokencky, P.M. l_ang, P.P. Tans, R.C. Martin, and K.A. Mamrie (1992), Slowing down of the global accumulation of atmospheric methane during the 1980s, Nature 358, 313-316.

Yagi, K., and K. Minarni (1990), Effect of organic matter application on methane emission from Japanese paddy fields, Soil Science Plant Nutr., 36, 599-610.