El Niño–southern oscillation influences on rice production in Sri Lanka

Abstract

Despite advances in the capacity to predict the evolution of the El Niño-southern oscillation (ENSO) phenomenon and advances in understanding the influence of ENSO on rainfall in tropical regions such as Sri Lanka, there has been limited use of climate predictions for agricultural decision-making. Climatic fluctuations have a profound influence on the cultivation of crops such as rice, which is the staple food in Sri Lanka. Here, the relationship between the sea-surface temperature-based ENSO index of NINO3.4, rainfall and the departure of Sri Lankan rice production from long-term trends, is analysed for the 'Maha' (October to March) and 'Yala' (April to September) cultivation seasons between 1952 and 1997.During the El Niño phase, the Maha rice production frequently increased (10 out of 15 seasons) and the Yala production frequently decreased (10 out of 14 seasons). Conversely, during the La Niña phase, the Maha production decreased (seven out of ten seasons) and Yala production increased (six out of eight seasons). Floods, state interventions, civil disturbances, fertilizer price hikes and extreme anomalies in the previous season were noted in the majority of seasons in which these ENSO-production linkages were violated.The correlation of the Maha rice production anomaly with the average NINO3.4 from October to December was significant at the 5% level and that with the aggregate October to December rainfall was significant at the 1% level. Yala rice production showed a significant relationship with concurrent NINO3.4 and a strong correlation (r = 0.60) with the previous season's rainfall. Yala cultivation is water constrained, and carryover storage from the previous season is often used to determine the extent of planting.The relationships between ENSO and seasonal rice production and the relationship between Yala rice production and previous Maha rainfall could be used for agricultural management and policy formulation.

Predictability of Sri Lankan rainfall based on ENSO

“…For example, there is strong reduction of stream flow from January to September during El Niño episodes (Zubair, 2003a). The rice production in the Yala (April-August) season is significantly reduced during El Niño periods (Zubair et al, 2002b).…”

“…The October to December rainfall coincides with the commencement of the main cultivation season of Maha (October-March). The April to June rainfall coincides with the commencement of the subsidiary cultivation season of Yala (April-September) (Zubair, 2002b). The rainfall peaks coincide with the passage of the Inter-Tropical Convergence Zone (ITCZ) over the island around May and October.…”

“…This figure is available in colour online at www.interscience.wiley.com/ijoc undergoes a reversal, with anomalous convection that prevailed over eastern Africa until September extending to cover an area that includes Sri Lanka until December. During El Niño events, the rainfall is enhanced from October to December and diminished from January to March and July to August (Rasmusson and Carpenter, 1983;Suppiah, 1996;Zubair, 2002b).…”

Impact of El Niño–southern oscillation on Indian foodgrain production

“…The influence of ENSO-related climate variability on agricultural production has been shown in Australia (Nicholls, 1985), the USA (Handler, 1990;Carlson et al, 1996;Hansen et al, 1998), Zimbabwe Phillips et al, 1998) and Sri Lanka (Zubair, 2002). In India, the foodgrain production was estimated based on observed SMR (Parthasarathy et al, 1988a(Parthasarathy et al, , 1992Gadgil et al, 1999).…”

Morphological Diversity of Complex Thalloid Liverwort Genera of Sri Lanka

“…Three major climatic zones are identified based on the mean annual precipitation; wet (2500-5500 mm of rain per annum), intermediate (1900-2500 mm) and dry (<1900 mm) (Dissanayake, 1991;Zubair, 2002) (Fig. 1C).…”