University of Maryland researchers investigated how long Cry proteins
persist in SmartStax corn when subjected to four post-harvest practices.
The results are published in/Transgenic Research/.

Cry protein levels are expected to decline over time due to microbial
decomposition and leaching. Thus, the researchers tracked how long
biologically active Cry proteins last in SmartStax corn residue
expressing Cry1A.105, Cry1F, Cry2Ab2, Cry3Bb1, and Cry34/35Ab1, when
exposed to four post-harvest practices including chisel plow tillage,
flail mowing, cover crop planting, and undisturbed residue.

Results showed that Cry proteins continued biological activity for as
long as 24 weeks after harvest when residue was left above ground with
less soil contact.

Degradation of transgenic Bacillus thuringiensis proteins in corn tissue
in response to post-harvest management practices | SpringerLink
[link.springer.com]