Potential impacts of dry SO2 deposition on crop yields in Mexico. A national scale approach

Abstract

Objective: the purpose of this work is to initiate a large scale approach of potential effects of SO₂ on agricultural yields in Mexico as it is one of the major emitting countries of a compound whit high impacts on vegetation.
Design/methodology/approximation: it is presented a statistical analysis of correlation (R) and linear regression (R2) between yields of 23 crops and average SO₂ ha^-1 concentrations at municipal level by 2011. Crops were differentiated according to its access to water (irrigated and rainfed), its life cycle (annual or perennial), and its sensitivity or resistance to SO₂. The P-value was applied in order to eliminate randomness in correlations. Significant correlation was observed in nine crops which accomplished simultaneously R?20%; R2?0.05; and P-value<0.05: plum, feed oat (green), feed oat
(dried), oat (grain), feed barley (green), feed barley (dried), feed corn (green), melon and grape.
Results: the average yields of the correlated crops were compared in three spatial contexts: national, municipalities with SO_2>0, and municipalities with the highest SO₂ concentrations. For the latter, the average yields of the resistant crops in the rainfed modality were 1.7 to 5.2 times greater than the national average, whereas for the sensitive crops, the yields were 12.9% to 57.8% lower. In the irrigated modality, the resistant crops obtained an increase of 59%, meanwhile sensitive crops throw yields 22% to 51.7% lower.