Climate Resilient Crop Zoning in Tamil Nadu, India: A 25 year assessment of major food crops

Agriculture in Tamil Nadu is strongly shaped by spatial and temporal climate variability, reflecting diverse agro‑climatic conditions and evolving resource constraints. Understanding the spatial performance of major food crops is essential for sustaining productivity in heterogeneous agro‑ecological regions. This study examines the spatio‑temporal dynamics of Efficient Cropping Zones (ECZ) for eight major food crops—rice, maize, sorghum, pearl millet, finger millet, red gram, green gram, and black gram—across Tamil Nadu over a 25‑year period (2000–2025). District‑level area and yield data were used to compute the Relative Yield Index (RYI) and Relative Spread Index (RSI), classifying districts into Most Efficient (MECZ), Yield Efficient (YECZ), Area Efficient (AECZ), and Non‑Efficient Cropping Zones (NECZ). Results reveal pronounced shifts in cropping efficiency driven by rainfall variability, monsoon fluctuations, groundwater depletion, soil fertility decline, and changing farmer preferences. Rice remained largely yield‑efficient in delta districts, while western and southern interior districts transitioned toward NECZ due to altered rainfall distribution and water stress. Maize showed expanding MECZ/YECZ zones supported by hybrid adoption and irrigation access, whereas sorghum and cumbu exhibited widespread efficiency decline linked to erratic monsoon performance. Millets retained resilience in traditional dryland belts, while pulses displayed contrasting trends, with black gram showing notable improvement and red/green gram exhibiting rainfall‑sensitive fluctuations. NECZ hotspots across multiple crops highlight priority districts for climate‑smart diversification toward drought‑tolerant millets, pulses, and oilseeds. Overall, the study demonstrates the value of periodic ECZ‑based assessments as a climate‑informed decision‑support tool for optimizing resource allocation, guiding crop diversification, and strengthening climate‑resilient food systems in Tamil Nadu.