the beneficial nematodes should be able to take the pressure just fine. The concern would be opening sizes on the drip nozzles. what is the opening size? We need them to be in the range of 400 micrometers, or larger, so the big good guys can get through.
Buying the predatory nematodes from the US doesn't make any sense, since the sub-species you have in OZ are adapted to your soil types, and climates. We do not have the same conditions in the US, so US-imports don't survive well in your conditions.
The exception is the conditions that you describe - where the soil has been fumigated. There is no decent life left in that soil, so addition of ANY kind of beneficials, OZ-adapted or not - will help immensely.
But, for long term survival, you want OZ-critters. So, keep looking for that compost made in OZ that has the predatory nematodes present.
Otherwise, stockpile some compost, and add predatory nematodes that you extract (you may want to talk to the Lismore lab and get them to save the predatory nematodes they find from all over OZ for you), into that stockpile. They should grow and increase in numbers, but it will take 6 months to a year for that to happen. They are slow-growers.
Hope this helps!
--
Elaine Ingham
President, Soil Foodweb Inc.
SFI Corvallis, OR
SFI Port Jefferson, NY
SFI Lismore, NSW, Australia
SFI Hilversum, The Netherlands
SFI Cambridge, New Zealand
SFI Culiacan, Mexico http://www.soilfoodweb.com