Comparison of rainfall patterns and rainfed maize yields in the Pacific region of Nicaragua and the Atlantic region of Colombia, 2007-2023

The effects of drought on non-irrigated maize yields in the Colombian Atlantic and in the Pacific of Nicaragua were analyzed within the scope of ENSO. The Standardized Precipitation Index (SPI-12m) was calculated for 2000-2024 and correlated with crop yields, resulting in a coefficient of determination (R2) of 0.52 between yields and SPI in the Pacific, a moderate correlation (R = 0.66) between regional yields (abs values)—although no correlation after removing series trend—, and a strong correlation (R = 0.80) between SPI values. ENSO affected rainfall regional patterns differently. In the Atlantic, more annual SPI values (10) were outside the normal range than in the Pacific, 60% due to drought, occurring twice consecutively (2001-2002 and 2014-2015). In the Pacific, three of the nine years outside the normal range were due to drought, while the other six were due to abnormally wet conditions, compared to four in the Atlantic. In both regions, abnormally wet conditions occurred consecutively from 2010-2011, although with greater intensity in the Atlantic (1.94, 1.32) than in the Pacific (1.64, 1.13), with 2022 being an extremely wet year (2.02 and 2.09). Even with an upward yield trend, rainfed maize productivity was vulnerable to extreme weather conditions, caused by drought in the Pacific, with the greatest decreases in 2009 and 2015 (–0.47 and –0.22), as well as excessive rainfall in the Atlantic in 2021 (–0.42). The Atlantic showed greater variability in yields (var = 0.097 vs. 0.03 for the Pacific), where prolonged ENSO of any intensity has a greater impact on rainfall patterns and yields.