You don't have to "cook" land weeds to drown them into a decomposed mush.. It's just a matter of time.
2 days is not long enough, and 2 years is excessive..
Take a couple mason jars of various weed roots and seeds and try 2 weeks, 2 months, then plant the stuff in a nice pot to see if anything grows (you should probably also do a "control" version soaked for just 2 days - or even just 2 hours - before potting to see if anything grows at all or if you suck so bad you just can't even grow weeds!
let me know your results!
tyronew888@yahoo.com