Impact of El Niño on Crop Productivity in Kerala

Abstract

Monthly rainfall data for the 14 districts of Kerala from 1985 to 2014 were used in the present analysis to compute the annual and seasonal rainfall. IITM's Sub divisional monthly rainfall data from 1951-2014 has been also used to get a clear picture of the El Niño effect on rainfall variability in Kerala. District-wise area, production and productivity data of two major crops paddy and coconut and state wise area, production and productivity data of other crops such as banana, pepper, tea, coffee, cashew and cardamom is collected from the Directorate of Economics and Statistics, Government of Kerala for the period 1985 to 2014. The weak El Niño was showing a positive influence on the crop yields of coffee, cardamom, banana and cashew, while a negative influence on 2 nd and 3 rd crop of paddy and tea and neutral effect on coconut and 1 st paddy crop. The crop yields of coconut, black pepper, tea, coffee, cardamom, banana, and cashew were negatively influenced by moderate El Niño episodes. The strong El Niño episodes was showing a negative impact on the crop yields of coconut, rice, black pepper, coffee, cardamom and cashew and a positive impact on the crop yields of tea and banana.

Full text

Research Paper
Research Journal of Agricultural Sciences
9(5): 1041-1045, September-October (2018)
ISSN: 0976-1675 https:
//
www.rjas.org DI: 5178-2506-2018-234
Impact of El Niño on Crop Productivity in Kerala
B Ajithkumar and Arjun Vysakh
Department of Agricultural Meteorology,
College of Horticulture, Kerala Agricultural University, Thrissur - 680 656, Kerala, India
e-mail: ajithagromet@gmail.com
Received: 25 June 2018; Revised accepted: 22 August 2018
A B S T R A C T
Monthly rainfall data for the 14 districts of Kerala from 1985 to 2014 were used in the present analysis to compute
the annual and seasonal rainfall. IITM's Sub divisional monthly rainfall data from 1951-2014 has been also used to
get a clear picture of the El Niño effect on rainfall variability in Kerala. District-wise area, production and
productivity data of two major crops paddy and coconut and state wise area, production and productivity data of
other crops such as banana, pepper, tea, coffee, cashew and cardamom is collected from the Directorate of
Economics and Statistics, Government of Kerala for the period 1985 to 2014. The weak El Niño was showing a
positive influence on the crop yields of coffee, cardamom, banana and cashew, while a negative influence on 2nd
and 3rd crop of paddy and tea and neutral effect on coconut and 1st paddy crop. The crop yields of coconut, black
pepper, tea, coffee, cardamom, banana, and cashew were negatively influenced by moderate El Niño episodes.
The strong El Niño episodes was showing a negative impact on the crop yields of coconut, rice, black pepper,
coffee, cardamom and cashew and a positive impact on the crop yields of tea and banana.
Key words: Rice, El Niño, Weak, Moderate, Strong episodes
griculture is sensitive to short term changes in
weather and to seasonal, annual and long term
variations in climate. The climatic elements affect the plant
growth and development. Monsoon rainfall is a key factor in
determining the agricultural productivity. Among the many
climatic factors influencing Indian monsoons, El Niño is one
global phenomenon found to have had a strong bearing on
the intensity of monsoon variations. Understanding the
impact of El Niño-Southern Oscillation (ENSO) on the
monsoon rainfall at regional scale is important to balance
agricultural production. The term El Niño (Spanish for “the
Christ Child”) was originally used by fishermen along the
coasts of Ecuador and Peru to refer to a warm ocean current
that typically appears around Christmas time and lasts for
several months. Over the years, the term “El Niño” has
come to be reserved for these exceptionally strong warm
intervals that not only disrupt the normal lives of the
fishermen, but also bring heavy rains (Prasad et al. 2014) to
the equatorial coast of South America, and convective
storms and hurricanes to the central Pacific region (Fig 1).
It is worth highlighting that although records of El Niño
are available from the 19th century, the correlation between
the monsoon rainfall and El Niño seems to have
strengthened only in the recent past. Since 1950, there were
23 El Niño years and only 13 drought years and three of
these droughts were in non-El Niño years. However, since
1980, all Indian droughts happened in the years of El Niño,
but all El Niño years did not result in droughts. The
occurrence of El Niño or La Niña may affect the food grain
production.
Fig 1 El Niño conditions
Most of the El Niño occurred have brought a reduction
in food grain production and the occurrence of La Niña
have brought an increse in the food grain production in
many cases (Selvaraju 2003). A high annual maximum
temperature may resulted in low yield in black pepper
(Gopakumar 2011). Kannan et al. (1987) observed that
blossom showers of 20 - 40 mm during February-March and
A
1041

backing showers of 50-75 mm during March - April are
considered to be critical for flowering and fruit set in
Robusta coffee. Failure of any of these rains will lead to
poor coffee yields. The state Kerala is bestowed with high
rainfall with uni and bimodal distribution. Though Kerala is
identified as a plantation State, the major staple food crop is
rice. Cash crops include coconut, arecanut, rubber, cashew,
tea, coffee and cocoa. Black pepper, cardamom, cinnamon,
clove, turmeric, ginger, nutmeg and vanilla are major spice
crops. The present study is meant to describe the impact of
El Niño on crop productivity in Kerala.
MATERIALS AND METHODS
Monthly rainfall data for the 14 districts of Kerala from
1985 to 2014 were used in the present analysis to compute
the annual and seasonal rainfall viz. southwest monsoon
(June-September), northeast monsoon (October- December)
and summer rainfall (March-May). The IITM's Sub
divisional monthly rainfall data from 1951-2014 has been
also used to get a clear picture of the El Niño effect on
rainfall variability in Kerala. The standardized rainfall
anomaly, which is the ratio of the difference of each year
rainfall from the mean to the standard deviation of rainfall,
has been used to identify the deficient and excess rainfall
years. The interannual variability of annual and seasonal
rainfall has been analyzed to relate it with El Niño.
Percentage change in rainfall in annual and seasonal time
scale has been computed in each of the categories of El Niño
(weak, moderate and strong) for the analysis. Monthly
maximum, minimum and mean temperature data for whole
Kerala and for six districts of Kerala were used to analyze
the temperature variation during El Niño and La Niña years.
District-wise area, production and productivity data of
two major crops paddy and coconut and state wise area,
production and productivity data of other crops such as
banana, pepper, tea, coffee, cashew and cardamom is
collected from the Directorate of Economics and Statistics,
Government of Kerala for the period 1985 to 2014. There is
a considerable decrease in crop area especially of rice is
present due to the reasons other than weather such as high
labour cost. So all the analysis have been done using the
crop productivity data.
RESULTS AND DISCUSSION
Effect of El Niño on rainfall and thermal regime of Kerala
The percentage change in annual and seasonal rainfall
during El Niño and La Niña years of Kerala has been
analyzed using IITM's sub divisional rainfall data from 1951
to 2014 and is presented in the (Fig 2). The south west
monsoon (-4.11%) and summer (-2.26%) rainfall is below
normal during El Niño years. The rainfall during NEM
season is found to be above normal (3.06%) during El Niño
years. The weak El Niño favours NEM and summer rainfall,
while moderate El Niño negatively influences SWM and
summer rainfall. During El Niño years, Annual, SWM and
NEM mean temperature anomaly in all the districts is
positive, while winter mean temperature anomaly is negative
in all the districts, except Thrissur and Thiruvananthapuram.
The annual and seasonal maximum and minimum
temperature anomaly in El Niño and La Niña years (Fig 3).
Fig 2 Percentage deviation from normal in annual and seasonal
rainfall of Kerala during El Niño and La Niña years
Fig 3 Annual and seasonal maximum, minimum and mean
temperature anomaly
Effect of El Niño on crop productivity in Kerala
Coconut
District wise productivity of coconut in different El
Niño episodes is given in the (Table 1). The coconut
productivity is not affected by weak El Niño. The
percentage change in coconut productivity is positive for all
the districts in weak Episodes except for Idukki and
Kozhikode. NEM rainfall was less than normal for
Kozhikode in weak El Niño period. The percentage change
in coconut productivity during moderate El Niño years is
negative for all the districts. The percentage change in
annual and southwest monsoon rainfall is negative in
moderate El Niño composite. This reveals the direct relation
between the rainfall and coconut productivity. During
Strong El Niño years also, coconut productivity was found
to be below normal for the districts viz. Kottayam, and
Alappuzha (problem area zone), Thrissur and Kasaragod.
The range in temperature is also found to be high during El
Niño years in SWM season. These factors could have
affected the crop productivity during strong El Niño years.
Ajithkumar and Vysakh
Research Journal of Agricultural Sciences 9(5)
1042

Table 1 Average yield and percentage change in yield of coconut in weak, moderate and strong El Niño episodes
Districts
Average yield
(kg/ha)
Weak
Moderate
Strong
Mean yield
(kg/ha)
% Change
in Yield
Mean yield
(kg/ha)
% Change in
yield
Mean yield
(kg/ha)
% Change
in Yield
Thiruvananthapuram
6421
7271
13
5852
-9
6359
-1
Kollam
5588
7271
30
4702
-16
5549
-1
Pathanamthitta
5412
5515
2
3863
-29
6047
12
Alappuzha
5556
6606
19
5320
-4
5347
-4
Kottayam
4623
5097
10
4336
-6
4078
-12
Thrissur
6474
7765
20
6112
-6
4423
-32
Ernakulam
5702
6101
7
5578
-2
5627
-1
Palakkad
5343
6587
23
3914
-27
5379
1
Malappuram
6551
7804
19
5238
-20
6649
1
Kozhikode
6625
6472
-2
5899
-11
6715
1
Kannur
5946
6898
16
5005
-16
6354
7
Kasaragod
6564
7459
14
5087
-23
6040
-8
Idukki
4232
3884
-8
4048
-4
5083
20
Wayanad
3019
3717
23
2504
-17
2864
-5
Rice
El Niño alters the rainfall and temperature distribution
in Kerala. Low rainfall and high temperature during El Niño
could affect the rice productivity. Percentage change in rice
productivity of first crop (Virippu; April-May to September-
October) in the weak, moderate and strong years is shown in
(Table 2). So the variation in south west monsoon rainfall
affects the autumn crop yield to a large extent. The first
paddy crop yield is not affected by weak El Niño in all the
districts except the central zone districts and northern zone
district Kannur. Crop yield is not affected by moderate El
Niño except for Alappuzha district, even though the rainfall
is found to be below normal in all the districts. Strong El
Niño has adversely affected the crop yield in all the districts
except in Alappuzha. The percentage deviation of SWM
rainfall is positive in all the districts during strong El Niño
years. So the heavy rainfall events in strong El Niño years
could have affected the crop yield in autumn season. The
high temperature noted in the El Niño year during the crop
season also would have caused reduction in the crop yield.
Table 2 Average and percentage change in paddy yield of first crop in weak, moderate and strong El Niño episodes in autumn
Districts
Average yield
(kg/ha)
Weak
Moderate
Strong
Mean yield
(kg/ha)
% Change
in Yield
Mean yield
(kg/ha)
% Change in
yield
Mean yield
(kg/ha)
% Change
in Yield
Thiruvananthapuram
2466
2509
2
2611
6
2286
-7
Kollam
2359
2420
3
2570
9
2063
-13
Pathanamthitta
2220
2306
4
2456
11
2159
-3
Alappuzha
2437
2908
19
2318
-5
2628
8
Kottayam
2598
2733
5
2839
9
2364
-9
Idukki
2623
2661
1
3091
18
2316
-12
Ernakulam
2042
1950
-5
2251
10
1790
-12
Thrissur
2029
1949
-4
2169
7
1893
-7
Palakkad
2518
2299
-9
2725
8
2359
-6
Malappuram
2012
2154
7
2031
1
1796
-11
Kozhikode
1333
1349
1
1453
9
1158
-13
Wayanad
No first crop for paddy
Kannur
2006
1898
-5
2156
7
1790
-11
Kasaragode
2323
2380
2
2435
5
2152
-7
The second paddy crop (Mundakan; September-October
to December-January) may be influenced by the Northeast
monsoon rainfall and temperature during October to
December. Percentage change in rice productivity of second
crop in the weak, moderate and strong years is shown in
(Table 3). Contrary to SWM rainfall, El Niño positively
influences the NEM rainfall and is found to be above normal
for majority of the districts in Kerala. But the maximum and
minimum temperature is more during El Niño years in NEM
season. These conditions may led to a reduction in crop
yield in all the districts during strong El Niño episode years
and crop yield is below normal for majority of the districts
in weak El Niño episodes. But, the crop yield is better in
moderate El Niño episodes in Mundakan season. Only in
Impact of El Niño on Crop Productivity in Kerala
1043

two central zone districts, a small reduction in paddy yield
was observed, where rainfall was also below normal during moderate El Niño episodes.
Table 3 Average and percentage change in paddy yield of second crop in weak, moderate and strong El Niño episodes in
winter
Districts
Average yield
(kg/ha)
Weak
Moderate
Strong
Mean yield
(kg/ha)
% Change
in Yield
Mean yield
(kg/ha)
% Change in
yield
Mean yield
(kg/ha)
% Change
in Yield
Thiruvananthapuram
2252
2477
10
2243
0
2036
-10
Kollam
2233
2233
0
2364
6
2060
-8
Pathanamthitta
2499
2367
-5
2726
9
2215
-11
Alappuzha
2706
2641
-2
2838
5
2505
-7
Kottayam
2648
2392
-10
2995
13
2240
-15
Idukki
2643
2463
-7
2719
3
2372
-10
Ernakulam
2105
2019
-4
2252
7
1810
-14
Thrissur
2323
2210
-5
2269
-2
2125
-9
Palakkad
2506
2472
-1
2403
-4
2447
-2
Malappuram
1998
1994
0
2120
6
1849
-7
Kozhikode
1380
1375
0
1524
10
1170
-15
Wayanad
2551
2520
-1
2640
4
2313
-9
Kannur
1976
1965
-1
2070
5
1792
-9
Kasaragode
2059
2108
2
2308
12
1760
-15
Summer rainfall during March and April period
influences the third crop (Puncha; December-January to
March-April) yield. Percentage change in rice productivity
of third crop in the weak, moderate and strong years is
shown in (Table 4). Weak El Niño causes excess rainfall and
strong El Niño causes deficient rainfall during the summer
season. Both these extremes affect the crop yield adversely.
The southern zone district, Thriuvananthapuram, where the
southwest monsoon rainfall is minimum got benefited by the
good summer showers in weak El Niño episodes and as a
result achieved 18% above normal yield. Crop yield is above
normal in Thrissur, Wayanad and Malappuram in weak
episodes. Heavy rainfall in weak El Niño could have
affected crop yield of all the other districts, except the above
mentioned districts. Decline in moderate rainfall in the
summer season has affected southern zone districts
Thiruvananthapuram and Kollam to a large extent.
Comparatively lesser number of districts (5 out of 14) only
got adversely affected by moderate El Niño during summer
season. Summer rainfall was below normal during strong El
Niño episodes in all the districts except Palakkad. A decline
in crop yield was observed in all the districts during strong
El Niño episodes.
Table 4 Average and percentage change in paddy yield of third crop in weak, moderate in summer
Districts
Average yield
(kg/ha)
Weak
Moderate
Strong
Mean yield
(kg/ha)
% Change
in Yield
Mean yield
(kg/ha)
% Change in
yield
Mean yield
(kg/ha)
% Change
in Yield
Thiruvananthapuram
1724
2031
18
1048
-39
1208
-30
Kollam
1504
1333
-11
1243
-17
1398
-7
Pathanamthitta
3317
3023
-9
4047
22
2654
-20
Alappuzha
3011
2575
-14
3798
26
2572
-15
Kottayam
3010
2509
-17
3303
10
2450
-19
Idukki
2634
2566
-3
2121
-19
2410
-9
Ernakulam
1949
1803
-8
2095
7
1637
-16
Thrissur
2989
3283
10
2977
0
2673
-11
Palakkad
2639
2337
-11
2786
6
2494
-5
Malappuram
3132
3426
9
2995
-4
2812
-10
Kozhikode
1874
1841
-2
1901
1
1689
-10
Wayanad
2711
2832
4
2717
0
2658
-2
Kannur
1578
1243
-21
1466
-7
1309
-17
Kasaragode
2045
2026
-1
2111
3
1904
-7
Other crops
The percentage change in productivity of other major
crops such as banana, black pepper, tea, coffee, cashew and
cardamom is shown in (Table 5). In the present analysis,
high annual rainfall and lowest productivity (-25%) is
observed in the black pepper during strong El Niño
Ajithkumar and Vysakh
Research Journal of Agricultural Sciences 9(5)
1044

episodes. High summer rainfall followed by the low SWM
rainfall in weak El Niño also contributes to 3% reduction in
pepper productivity. Low rainfall in SWM season and high
rainfall in NEM season during Moderate El Niño also cause
3% reduction in pepper productivity. Increased maximum
and minimum temperature also resulted in reduction of crop
yield during El Niño episodes.
Table 5 Average yield and percentage change in yield of pepper, tea, coffee, cardamom, cashew and banana in weak,
moderate and strong El Niño episode years
Crop
Average
yield
(kg/ha)
Weak
Moderate
Strong
Combined
Yield
(kg/ha)
% change
in yield
Mean yield
(kg/ha)
% change
in yield
Mean yield
(kg/ha)
% change
in yield
Mean yield
(kg/ha)
% change
in yield
Pepper
314
306
-3
304
-3
235
-25
281
-10
Tea
1716
1458
-15
1542
-10
1786
4
1595
-7
Coffee
612
671
10
508
-17
516
-16
565
-8
Cardamom
157
207
32
100
-36
126
-20
145
-8
Cashew
761
809
6
745
-2
755
-1
770
1
Banana
7784
7949
2
7211
-7
8320
7
7827
1
The tea yield was found to be high when annual rainfall
is low. In the present analysis, tea yield is found to be high
in strong El Niño episodes, when the annual rainfall is also
high. Annual rainfall in the moderate El Niño is low and the
tea yield is also found to be low. But annual rainfall in weak
El Niño is high due to good summer showers and the tea
yield is lowest (-15%) in the weak El Niño episodes.
Rainfall seems to be the most important factors among
various weather elements influencing flowering and yield of
coffee. This observation is consistent with the present
analysis. Summer rainfall is always high during weak El
Niño and the coffee yield is found to be 10% more in weak
El Niño periods. In moderate and strong El Niño episodes,
summer rainfall and the coffee yield was found to be below
normal. Coffee yield is -17% in moderate El Niño episodes
and -16% in strong El Niño episodes. Coffee yield appears
to be poor when the maximum temperatures go beyond
26.9°C. Interestingly, there was a negative relationship
between the mean temperature and coffee yield. So the
increased mean temperature during El Niño would have
contributed to the low coffee yield in moderate and strong El
Niño periods.
Cardamom yield is highest during weak El Niño
episodes and lowest in the moderate El Niño episodes. So
the good summer showers help in achieving high good yield
of cardamom as in the case of coffee. Summer showers help
to produce more number of tillers which in turn facilitate to
bear more fruits. When the annual maximum temperature
was high, the yield tends to be low and when it was low, the
yield tends to be high. High annual temperature during El
Niño can be a reason for the reduction in cardamom yield in
moderate El Niño and strong El Niño years. The banana and
cashew yield is slightly affected by the El Niño. The crop
yield was found to be high in weak El Niño and low in
moderate El Niño years.
The coconut productivity is not affected by weak El
Niño, while it was affected by moderate and strong El Niño
episodes. During first crop season, the paddy yield was not
affected by weak and moderate El Niño episodes in almost
all the districts, while it was adversely affected by strong El
Niño episodes. During the second and third crop season,
paddy yield is reduced during weak and strong El Niño
episodes in majority of the districts, while the paddy yield
was better or not much affected in moderate El Niño
episodes. The strong El Niño episodes adversely affected the
black pepper yield, while it was less affected by the
moderate and weak El Niño episodes. The tea yield was
found to be low in weak and moderate El Niño episodes and
high during strong El Niño episodes. During weak El Niño
episodes, the coffee and cardamom yield was found to be
high and low yield obtained during moderate and strong El
Niño episodes. The banana and cashew yield slightly
affected by the El Niño epiosodes.
LITERATURE CITED
Gopakumar C S. 2011. Impacts of climate variability on agriculture in Kerala. Ph. D. Thesis, Cochin University of Science
and Technology, Cochin, Kerala. pp 268.
Kannan K, Devadas V S and Thomas C G. 1987. Effect of weather parameters on the productivity of coffee and pepper in
Wayanad. In: National Seminar on Agrometeorology of plantation crops, 12-13 March 1987, RARS, Pilicode. pp 187.
Prasad R, Rao V U M and Rao B B. 2014. El Niño-its impact on rainfall and crop productivity: A case study for Himachal
Pradesh. CSKHPKV, Palampur, HP and CRIDA, Hyderabad, India. pp 24.
Selvaraju R. 2003. Impact of El Nino-southern oscillation on Indian food grain production. International Journal of
Climatology 23: 187-206.
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