Influence of pesticides on acetylene reduction and growth of microorganisms in an organic soil¹

Contribution No. 740, Research Institute, Agriculture Canada, London, Ontario, Canada N6A 5B7.

Abstract

The effects of 32 pesticides at two concentrations on acetylene reduction (non‐symbiotic nitrogen fixation), nitrogen fixers, bacteria and fungi in an organic soil were assessed. None of the pesticide treatments suppressed C H reduction as compared to controls. No significant inhibition of the population of non‐symbiotic nitrogen fixers occurred. However, stimulatory effects were observed with treatments of fensulfothion, fonofos, oxamyl, DD^R , Telone^R and Telone C^R . Bacterial and fungal populations showed temporary declines but all recovered within 7 days to levels similar to or higher than those in the controls.

Key words:

• Acetylene reduction
• organic soil
• non‐symbiotic
• nitrogen fixation
• pesticides
• microorganism

Notes

Contribution No. 740, Research Institute, Agriculture Canada, London, Ontario, Canada N6A 5B7.