Persistence of Bacillus thuringiensis and Bacillus cereus in soil supplemented with grass or manure
Authors: West, A. W., Burges, H.D.
Journal, Volume, Year: Plant and Soil, volume 83:389-398, 1985
Persistence of Bt spores plus parasporal crystals in soil supplemented with dried grass or dried manure. Bt insecticidal activity (in Pieris brassicae bioassay) was lost steadily in both supplemented soils. The grass supplements had a half-life = 9.5 The manure supplemented soils had no significant change in activity for 12 days, then had a half-life = 8.5 days.
The study used only spores and not purified toxin or transgenic toxin. Most retention of activity is probably due to growth of spore populations.