Denitrification in a chinampa soil of Mexico City as affected by methylparathion: a laboratory study.

摘要

Chinampas are raised garden beds used for agriculture in the valley of Mexico since pre-Hispanic times. Large amounts of methylparathion, i.e. approximately 0.5 kg ha-1 per crop cycle, are used to control pests with an unknown effect on soil processes, such as the denitrification process. Soil was amended with nitrate (NO₃-) with or without chloramphenicol known to inhibit de novo synthesis of enzymes, with or without acetylene (C₂H₂) known to inhibit the reduction of nitrous oxide (N₂O) to dinitrogen (N₂) and spiked with or without methylparathion. Methylparathion increased the N₂O and N₂ emissions, the NO₂- concentration and removal of NO₃- from soil. The NO₂- concentration in the anaerobic incubation was larger when soil was conditioned aerobically <7 days compared to soil conditioned for >7 days, but no such pattern was observed for the removal of NO₃-. C₂H₂ and/or chloramphenicol had no significant effect on NO₃- removal and the NO₂- concentration in the methylparathion-amended soil, but increased the NO₂- concentration in unamended soil with C₂H₂ plus chloramphenicol compared to the other treatments. C₂H₂ increased the N₂O emission in soil amended with or without methylparathion and with or without chloramphenicol.