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Biocides and soil life: effects beyond the target organism

Ingham and Coleman’s 1984 study examines eight biocides and their effects on bacteria, fungi, protozoa and nitrogen forms.

Study published: December 1984 · Sources checked: 22 October 2026

The question

Elaine Ingham and David Coleman examined eight biocides, asking how effectively they reduced target organisms and how they affected other soil organisms. The work included simplified laboratory microcosms containing bacteria, fungi and protozoa, alongside separate experiments with plants. [1]

The main observations

Every biocide also affected non-target organisms. These increases or decreases were temporary, while reductions in target groups usually lasted longer. Bacterial populations often increased following fungal reductions. Diazinon reduced all measured microbial populations and inorganic nitrogen concentrations. [1]

Dose and feeding relationships matter

Responses to streptomycin differed between the tested doses. At the higher dose, counts of certain bacteria and active fungal hyphae declined. The experiment therefore describes wider interactions as well as direct effects on a target group. [1]

Connecting the findings with our work

The study concerns laboratory conditions and the substances examined at the time. For our Center, it raises a question about how an intervention affects relationships throughout the soil community. We aim to record application history alongside changes in soil life, interpreting observations in their field context.

This presentation draws on the published scientific abstract. The educational connection with our Center’s work is our editorial synthesis.

← Elaine Ingham · Research and publications