Rainfall Variability, Temperature Fluctuations and Structural Crop Divergence in Tamil Nadu: Empirical Evidence from Irrigated and Rain-fed Agriculture (2000–2023)

Sowndharya S and Jayachandran S. Sindhu*

PG and Research Department of Economics, Agurchand Manmull Jain College, Chennai, Tamil Nadu, India. Corresponding Author: sindhu.j.s@amjaincollege.edu.in

Abstract:

Tamil Nadu’s agricultural sector is increasingly affected by climate variability, particularly fluctuations in rainfall and temperature, which create uncertainty in agricultural production and cropping patterns. This study examines the relationship between climate variability and structural crop divergence in Tamil Nadu during the period 2000-2023 using annual data obtained from the India Meteorological Department (IMD) and the Directorate of Economics and Statistics, Tamil Nadu (DES-TN). Ordinary Least Squares (OLS) time-trend regression and Pearson correlation are used as the primary analytical tools to assess relationships between climatic variables and crop performance. Rice is used as the representative crop for correlation analysis owing to its status as Tamil Nadu's principal food crop and its direct dependence on monsoon rainfall during critical growth stages. The results show that rainfall variability in Tamil Nadu is high, with a coefficient of variation of 14.58% and an annual range between 780 mm and 1,420 mm. Rainfall shows a strong positive correlation with rice production (r = 0.806, p < 0.01), while the number of rainy days is also positively associated with agricultural output (r = 0.741, p < 0.01). In contrast, mean temperature has a significant negative relationship with rice production (r = −0.540, p < 0.01), indicating that higher temperatures are associated with lower crop output. Although no statistically significant long-term warming trend was identified during the study period, year-to-year temperature fluctuations were sufficient to affect crop performance. The study also identifies a clear divergence between irrigated and rain-fed agriculture. Irrigated crops such as rice, sugarcane, and cotton show positive production trends, whereas rain-fed crops, particularly groundnut and millets, exhibit long-term decline. The findings suggest that agricultural risk in Tamil Nadu is more strongly associated with climate variability than with gradual warming trends, underscoring the need for policy interventions focused on irrigation expansion, development of climate-resilient rainfed crop varieties, and strengthened seasonal forecasting systems.

Keywords:

Climate Variability; Irrigated and Rain-fed Agriculture; Ordinary Least Squares (OLS) Time-Trend Regression; Pearson Correlation; Rainfall Variability; Rice Production; Structural Crop Divergence; Tamil Nadu; Temperature Fluctuations

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