I did not read the link you are considering, but for nematodes somewhere I heard that diatomaceous (sp?) earth is the ticket, and that the cheapest version is used for swimming pool filters, so that is what I use. As to whether it works or not I am like the guy snapping his fingers to keep the elephants away (old joke from 1960's). I mix in a little anytime I add dirt or fert to the bananas and they do reasonably well.
(Edit 2-27-18 I just got 2 bags of the "Dicalite" swimming pool stuff, and, uh, just now looked it up to see if it should work against nematodes. "No" is what people say, like here:
http://biconet.com/crawlers/infoshee...thPestCtrl.pdf The key search word is "calcined". Sorry. Ray)