Stimulation of nitrous oxide production resulted from soil fumigation with chloropicrin

Agricultural soils are a major source of the atmospheric greenhouse gas nitrous oxide (N2O). Agronomic practices such as tillage and fertilizer applications can significantly affect the production and consumption of N2O because of alteration in soil physical, chemical, and biochemical activities. Soil fumigation is an agronomic practice used to control soil-borne disease pathogens, weeds, plant-parasitic nematodes, and fungi. The strong impact of fumigants on soil microorganisms can indirectly affect the production and/or consumption of N2O and would potentially alter net emissions from agricultural soils. Laboratory incubation and field soil fumigation studies were conducted to determine the potential impact of soil fumigation on the dynamics of N2O production. Laboratory soil incubations showed an eight-fold increase in the production rate of N2O as a consequence of chloropicrin (CP) fumigation. This stimulation effect was confirmed by a seven-fold increase in N2O emission rates in field plots following CP fumigation. The mechanism of N2O production appeared to be microbial related; however, additional work is needed to fully elucidate the pathways.