Impact of air pollutants on agriculture

Air pollutants change plant metabolism, yield, crop quality, soil fertility, temperature regimes and hydrology. Type of air pollutants, deposition rate and structure of ecosystem bias the effects on agriculture. Increased CO2 concentrations generally cause positive effects through increased root mass, litter and crop residues thereby increasing soil organic matter and plant growth. Accelerated CO2 concentrations are associated with higher temperatures entailing negative effects on soils. The reduction Of SO2 emissions has a major effect on the productivity of agricultural crops (yield losses, reduced natural resistance, increased non point N losses, increase of surface ozone concentration). N depositions contribute indirectly to N2O emission through an increased amount of N in the nutrient balance. Deposition of ammonia compounds is a primary cause of soil acidification. Ammonia contributes to transboundary air pollution and nitrogen enrichment of nutrient-poor soils. Air pollutants affect agriculture and may endanger a sustainable crop production. That is inconsistent with the requirement to protect the natural resources soil, water, atmosphere, and energy.