I'm doing some work on urban farms that are using rather artificial soils. They consists of general type potting mixes which have been amended with lots of organic matter over the years. The soils have a rather low bulk density and are very high in organic matter, total nitrogen and CEC.

A few of the gardeners complained about root knot nematodes. They have been trying to get rid of them by planting mustards and similar plants, with little success. Because they are organic farmers they don't want to apply pesticides.

I collected soil samples (0-10 cm) and extracted nematodes from 100 ml of soil using a Buchner-funnel. In areas with lower plant density I counted between 250 and 800 nematodes.

In plots with higher plant density and more established plants I found up to 1800 nematodes.

Plants susceptible to root knot show clear signs of infection.

Can anyone put those nematode numbers in perspective?

Is it a lot compared to conventional agriculture or horticulture soils?

Is there a maximum of nematodes that any soil can support?

I took a video of those nematodes which I suspect might be of Meloidogyne sp. Can anyone confirm this? (Unfortunately not the best video quality but the best I could do)

https://streamable.com/mbvlj

I'm not very experienced with nematodes and this is the first little side-project I'm working with them. It would be very helpful if someone could tell me the severity of this nematode problem.