Impact of climate change on agriculture in Karnataka

Abstract

Karnataka state is having the second largest rainfed agricultural area in the Country and food production is mainly depending on the south-west monsoon. The State's mean annual rainfall is found to be in decreasing trend along with its sixteen years cyclic periodicity. The State first half century's (1901-1950) normal of 1204 mm has been reduced to 1140 mm during second half of the century (1951-2000). Nevertheless, few districts like Bengaluru, Kolar and Tumkur are gaining in their mean annual rainfall and some traditionally heavy rainfall receiving districts like Kodagu, Chikmagalur and South Canara are loosing in their mean annual rainfall. The eastern districts of the state are tending to be more dependent on North East monsoon than terminal rains of the South West monsoon. Consequently individual crop growing area, growing period are changing. The normal sowing season rains are being delayed due to the shift of July rains to the August month and September peak rainfall is being shifted to October month. The maximum water available period for the grand growth period is shifting towards the end of September and beginning of October in many districts. Finger millet crop area (main food crop of southern Karnataka) in Chikmagalur district, Groundnut area in Chitradurga and Tumkur districts, Red gram in Bidar and Gulbarga districts is increasing. Where as, Groundnut area in Belgaum and Gulbarga districts and Red gram area in Belgam and Tumkur is decreasing.

Full text

Impact of climate change on agriculture in Karnataka
M. B. RAJEGOWDA, B.T. RAVINDRA BABU, N.A. JANARDHANAGOWDA and K.S. MURALIDHARA
University of Agricultural Sciences, GKVK, Bengaluru-560 065.
ABSTARCT
Karnataka state is having the second largest rainfed agricultural area in the Country and food production is mainly
depending on the south-west monsoon. The State’s mean annual rainfall is found to be in decreasing trend along with its
sixteen years cyclic periodicity. The State first half century’s (1901-1950) normal of 1204 mm has been reduced to 1140
mm during second half of the century (1951-2000). Nevertheless, few districts like Bengaluru, Kolar and Tumkur are
gaining in their mean annual rainfall and some traditionally heavy rainfall receiving districts like Kodagu, Chikmagalur and
South Canara are loosing in their mean annual rainfall. The eastern districts of the state are tending to be more dependent
on North East monsoon than terminal rains of the South West monsoon. Consequently individual crop growing area,
growing period are changing. The normal sowing season rains are being delayed due to the shift of July rains to the
August month and September peak rainfall is being shifted to October month. The maximum water available period for the
grand growth period is shifting towards the end of September and beginning of October in many districts. Finger millet
crop area (main food crop of southern Karnataka) in Chikmagalur district, Groundnut area in Chitradurga and Tumkur
districts, Red gram in Bidar and Gulbarga districts is increasing. Where as, Groundnut area in Belgaum and Gulbarga
districts and Red gram area in Belgam and Tumkur is decreasing.
Key words: Climate change, rainfall, productivity, global warming
Journal of Agrometeorology 11 (2): 125-131 (Dec. 2009)
The Karnataka State is located between 11.5º N and
18.5º N latitude and between 74º E and 78.5º E longitude.
The mean elevation varies between 600 m to 900 m above
mean sea level (Rajegowda 1990). The State comprises of
ten Agro climatic zones. Global Climate change and its
impact on agriculture is becoming an important issue even
at the micro level. A slight change in the climate may lead to
major changes in plant and animal life. Rainfall is one of the
most important parameters that influence the agriculture of
the region and food production. Therefore, a case study was
taken up to analyze the rainfall pattern for few districts in
Karnataka state where rainfall is showing definite trend to
examine the cropped area variability for major crops. Sastri
and Urkurkar (1996) observed a decrease in pre-monsoon
rainfall in some parts of Chhattisgarh region in the months
of May and June which has detrimental effect on the pre-
sowing operations of rice crop. Saseendran et.al. (2000)
showed that the plausible climate change scenario for the
Indian subcontinent as expected by the middle of the present
century. Kumar et.al. (2001) estimated the relationship
between farm level net-revenue and climate variables in India
using cross-sectional evidence. Sinha et. al. (1988) indicated
that food supplies in smaller nations would be affected more
by climate change than those of larger nations.
MATERIALS AND METHODS
A case study has been taken up to analyze the rainfall
pattern of few districts in Karnataka State where rainfall is
showing definite trend and the cropped area variability trend
for major crops. Published data of rainfall and cropped area
of different districts were collected from Drought Monitoring
Cell- Bangalore and Directorate of Economics and Statistics-
Bangalore. Annual total rainfall for the years 1950 to 2006
is respect of several districts, zones and the state was analyzed
and plotted on time series. Similarly the districtwise cropped
area for the period from 1955-2006 was analyzed and with
time series. The trend in rainfall and the area under different
crops in several districts were examined and discussed.
RESULTS AND DISCUSSION
The time series of the mean annual rainfall of the State
indicates a definite cycle of sixteen years starting 1950 to
1964 and so on. The first half of the cycle received less than
the normal rainfall for the period from 1950 to 1958 and the
second half of the cycle received more than the normal for
the period from 1959 to 1964. During this half of the cycle,
two or three of eight years have received the rainfall opposite
to their trends. This cycle is repeated up to 2004 and the
state is in the positive half of the cycle from 2004 and likely
to continue till 2012 (Fig 1).
The State’s mean annual rainfall for the period from 1901
to 1950 was 1204 mm (Rajegowda et. al. 1990) and it during
the period 1951 to 2000 is reduced to 1140 mm (Annual Report
2003. Drought -2002). The mean annual rainfall of the State
for the period from 1901 to 2000 was reported to be in declining
(Panduranga et. al. 2006). There is s definite declining trend in
rainfall in Kodagu (Guruprasanna et. al. 2006), Chikmagalur
and South Canara districts. In Kodagu district, the mean annual
rainfall for the period 1901-1950 was reduced from 2725 mm
to 2625 mm during the period 1951-2006. Chikmagalur district’s
mean annual rainfall of 1927 mm declined to 1872 mm and

Dec 2009] 126Impact of climate change on agriculture in Karnataka
700
1100
1500
1900
50 55 60 65 70 75 80 85 90 95 2000 2005
Mean rainfall=1140mm
Mean rainfall=1140mm
Low High
Cyclic trend
Actual rainfall
Low Low LowHighHigh
Years
Fig 1: Cyclical trend of Karnataka State mean annual rainfall for the period from 1950 to 2006
800
1800
2800
3800
4800
5800
50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 0 2 4 6
Year
Rainfall (mm
)
Kodag u Chikmagalur
D.Kannada Linear (D.Kannada)
Line ar (Kodag u) Line ar (Chikmag alur)
Fig 2: Declining trend of rainfall in Kodagu, Chikmagalur and South Canara districts.
300
500
700
900
1100
1300
50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 0 2 4 6
Year
Rainfall (mm
)
Bengaluru Urban Kolar
Tumkur Linear (Tumkur)
Linear (Bengaluru Urban ) Linear (Kolar )
Fig 3: Increasing trend of rainfall in Bengaluru, Kolar and Tumkur districts.

127 [Vol. 11, No. 2RAJEGOWDA et al
1.4 9.1 14.7
27.9
100.4
70.8
114.3 109.4
216.7
135.0
55.6
13.8
1.8 5.0 11.3
45.1
96.3
113.6
73.0
158.7
191.5
237.9
65.7
16.0
0.0
50.0
100.0
150.0
200.0
250.0
Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec .
Month
Rainfall (mm)
Before 1990 After 1990
Fig 4: Rainfall shift in the Eastern Dry zone of Karnataka
0
50
100
150
200
250
300
350
400
72 75 78 81 84 87 90 93 96 99
Yea r
Rainfall (m
m
JUL. Aug. J.avg. A.avg
Fig 5: Declining in July rains and increasing in August rains in the Eastern Dry zone of Karnataka
Rice area
30000
50000
70000
90000
110000
130000
150000
170000
190000
1955 1960 1965 1970 1975 1980 1985 1990 1995
Year
Area (ha)
Mandya Mysore Linear (Mysore) Linear (
Fig 6: Increase in rice area in Mandya and Mysore districts and their trends

Dec 2009] 128Impact of climate change on agriculture in Karnataka
South Canara district’s mean annual rainfall of 3976 mm has
been reduced to 3960 mm for the corresponding periods which
clearly indicates declining trend and the same is shown in
figure.2. Further few districts of the state have shown increasing
trend in the annual rainfall. Bengaluru, Kolar and Tumkur
districts have shown the considerable increasing trend in the
annual rainfall. Their mean annual for the period from 1901 to
1950 are 867 mm, 745 mm and 688 mm respectively and
compared to are 883 mm, 767 mm and 730 mm respectively
for the period from 1951 to 2006. (Fig 2).
The Eastern Dry zone of Karnataka consists of Bengaluru
and Kolar districts and parts of Tumkur district. This Zone is
also called as the Tank fed region and constitutes 9.42 per cent
of the State’s geographical area. Eighty per cent of the area is at
an altitude of 800 -900 m above mean sea level (Rajegowda
1990). 47 per cent of its area is under agriculture/horticulture
crops. Rajegowda et. al. (2000) have shown that there is a
predominant shift in the initiation and termination of rainfall to
supply adequate moisture for crop growing period. This shift
was observed after 1990 and their mean monthly values also
have changed. Before 1990, the annual rainfall ranged from
619 to 1119 mm with a mean of 869 mm. After 1990, the annual
rainfall ranged between 611 and 1311 mm with a mean of 1011
mm. During the first period, on the average the peaks were
observed during the months May, July and September (Fig 4).
During the second period, the peaks were observed during the
months May, August and October months.
Consequently growing area under different is varying.
Crop growing period is changing and crop productivity is also
varying. The normal sowing season gets delayed due to the
shift of July rains to the month of August (Fig.5).The peak
normally occurring during September shifted to October The
maximum water available period for the grand growth period is
shifting towards the end of September and beginning of October
in many eastern districts.
The changes in cropped area under different crops in
various districts was examined for the period from 1950 to 2006.
It is observed that area under some crops is increasing while it
is decreasing in some districts over years. A definite was
observed for the following crops. The area under rice in Mysore
and Mandya districts, finger millet (Ragi) in Chikmagalur
district, Red gram in Bidar district and Groundnut in Chitradurga
and Tumkur districts is increasing (Figs 6 to 9). The decline of
area of in red gram area in Belgaum and Tumkur districts,
Groundnut in Belgaum and Gulbarga districts are shown in
figures 10 and 11 respectively. Such change in the cropped area
is found to be influenced mainly due to the availability of the
rain water during the cropping season.
The declining trend of annual rainfall in Kodagu,
Chikmagalur and South Canara districts in is The increasing
trend of annual rainfall in Bengaluru, Kolar and Tumkur districts
indicates better water availability to the for getting higher yield.
The distribution of rainfall during the cropping season
has high influence on the cropping area and crop selection. In
both the periods considered for this study, the quantum of May
rains received during both the periods more or less remain same.
The rainfall received during the south-west monsoon, i.e.,
starting from June to October which is the crucial period for the
growth of the crop apart from the hydrological utility is much
more important. The quantum of rain received during June is
low and it remains unchanged more or less in both the periods.
The average rainfall during July, which was 114.3 mm during
1972-90, decreased to 73.0 mm during 1991-99. This reduction
in July rains seems to be compensated by an increase in August
rains (158.7 mm) during 1991-99 compared to the period 1972-
90 (109.4 mm). This clearly shows that there is a perceptible
shift in rainfall pattern from July to August and also from
September to October in this Agroclimatic zone. A distinguished
peak was observed in the month of September (216.7 mm)
during 1972-90 and October was the next highest rainfall-
receiving month. The analysis of monthly rainfall beyond 1991
showed that the highest rains are now received during October
i.e. (237.9 mm) and the next highest rainfall is received during
September (191.5 mm). This implies that the peak, which was
being observed during 1972-90, has shifted to October during
1991-99. There is a marginal increase even in the rainfall of
November month after 1990.
The crop sown during July rains would reach the grand
growth period i.e., flowering to grain formation stage (long
duration crops of about 115 days) during September month
which was receiving the highest rainfall till 1990, so that there
was no moisture stress during the grand growth period. After
1990, as a result of reduction in July and September rains, the
crops can not be sown during July, though the land preparation
could be done using June rains. Even with scanty rains, if the
sowing is done during July, the crop would suffer from moisture
stress due to the reduction in rainfall during September and
also the crop grown would be caught in the October rains causing
considerable loss in the grain yield at the harvest. The change
in the mean monthly rainfall pattern beyond 1990 does not
favour the sowing of crops during July month. This analysis
reveals that the sowing of the crops (medium duration variety
crops of about 115 days) could be done during August preparing
the land using June and July rains. In the years of early onset of
south-west monsoon, sowing can be recommended during last
week of July also. The crop sown during August would reach
the grand growth period during October. As the October month
receives higher rainfall the crop in its grand growth period would
not suffer for want of moisture. The crop sown beyond August

129 [Vol. 11, No. 2RAJEGOWDA et al
Chickman
g
alur
0
20000
40000
60000
80000
100000
120000
140000
1955 1960 1965 1970 1975 1980 1985 1990 1995 200 0
Year
Area (ha)
Finger millet area
Fig 7: Increase in finger millet area in Chikmagalur district and its trend
Redgram area
0
50000
100000
150000
200000
250000
300000
350000
400000
1955 1960 1965 1970 1975 1980 1985 1990 1995 2000
Year
Area ( ha)
Bidar Gulburga Linear (Gulburga) Linear (Bidar)
Fig. 8: Increase in red gram area in Bidar and Gulbarga districts and their trends
Groundnut area
0
20000
40000
60000
80000
100000
120000
140000
160000
180000
200000
1955 1960 1965 1970 1975 1980 1985 1990 1995 2000
Year
Area ( ha )
Chitradurga Tumkur
Linear (Tumkur) Linear (Chitradur
g
a)
Fig 9: Increase in groundnut area in Chitradurga and Tumkur districts and their trends

Dec 2009] 130Impact of climate change on agriculture in Karnataka
R
0
5000
10000
15000
20000
25000
30000
1955 1960 1965 1970 1975 1980 1985 1990 199
Year
Are a ( ha )
Belgaum Tumkur Linear (Tumkur) Line
Fig. 10: Decrease in red gram area in Belgaum and Tumkur districts and their trends
Groundnut area
50000
70000
90000
110000
130000
150000
1955 1960 1965 1970 1975 1980 1985 1990 1995 2000
Year
Area (ha)
Belgaum Gulburga Linear (Belgaum) Linear (Gulburga)
Fig. 11: Decrease in groundnut area in Belgaum and Gulbarga districts and their trends
may not be able to complete its life cycle as a result of inadequate
moisture availability beyond 2nd fortnight of November (in the
event of the intensity of north-east monsoon being low) as crop
maturity coincides during this period. Under such
circumstances, the short duration variety crops have to be
preferred. Further micro level studies in quantum of rainfall
shift are needed.
The increasing in rice area in Mysore and Mandya districts
is due to increase in irrigation area and also reduction in rainfed
agriculture. In case of Chikmagalur district, the fingermillet area
s increasing due to the declining trend in rainfall. The farmers
are changing their crops to raise better crops based on the
available water through rain water. Hence, the area under finger
millet is increasing. Red gram in Bidar and Gulbarga districts
and Groundnut in Tumkur and Chitradurga districts is increasing
due to the decline in the terminal southwest monsoon rainfall
and increase in the northeast monsoon rainfall. In the same
districts the groundnut area is decreasing as the water
requirement is not met during the pod filling and pod maturity
of the crops as the September month rainfall is decreasing.
During this period, the redgram will not be affected as the crop
is in vegetative stage and does not demand more water and
hence the red gram area is increasing in these districts and
groundnut area is decreasing.
CONCLUSION
The state’s mean annual rainfall is found to be in
decreasing trend along with its sixteen years cyclic periodicity.

131 [Vol. 11, No. 2RAJEGOWDA et al
The State’s normal of 1204 mm is reduced to 1140 mm.
Bengaluru, Kolar and Tumkur are gaining in their mean annual
rainfall and some traditionally heavy rainfall receiving districts
like Kodagu, Chikmagalur and South Canara are loosing in their
mean annual rainfall. The eastern districts of the State are tending
to be more dependent on North East monsoon than terminal
rains of the South West monsoon. The predominant shift in
initiation and termination of rainfall to supply the adequate
moisture for crop growth has been observed in many agro
climatic zones of the state retaining the same length of rainy
period. Consequently to this, individual crop growing area is
varying, crop growing period is changing and crop productivity
is also varying. The normal sowing season rains are being
delayed due to the shift of July rains to the August month and
September peak rainfall is being shifted to October month. The
maximum water available period for the grand growth period is
shifting towards the end of September and beginning of October
in many districts.
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Received: December 2008; Accepted: July 2009