Key Microorganism: Protozoa

CC BY 2.0,

CC BY 2.0,

Protozoa are single-celled organisms consisting of three groups, flagellates, amoebae and ciliates, whose role in the soil food web is to consume bacteria and excrete plant-available forms of nutrients. Without proper numbers of protozoa in soil or compost, soluble nutrients are never released from decomposer bacteria and nutrient cycling does not occur.

The two groups we aim for are flagellates and amoebae, as they indicate aerobic conditions and release nutrients in forms that bolster crop health and resiliency.

Ciliates are indicators of anaerobic conditions because they prefer anaerobic bacteria and release nitrogen in the nitrate form preferred by pests, disease and weeds.

Recommended levels

The minimum populations of flagellates and amoebae should be 10,000 per gram of soil, preferably higher depending on where the crop falls in natural ecosystem succession. 

Learn more

Microworld - World of Amoebid Organisms