I consulted the oracle of Google, and the EPA has a data sheet for Aminopyralid here
Ctrl+F for "half-life" yields a bunch of different times, ranging from 31.5 to 533.2 days. EPA risk assessment standard is 103.5 days.
The EPA datasheet at the above link wrote:Under aerobic conditions, degradation of aminopyralid in five different soils resulted in
the production of CO2 and non-extractable residues. Half-lives ranged from 31.5 to
533.2 days in 5 soils. For risk assessment purposes, EPA used a half-life of 103.5
Aminopyralid photolyzed moderately slowly on a soil surface. The half-life was 72 days
and CO2, non-extractable residues and small amounts of acidic volatiles were the
So from there, just use a Half-Life Calculator
Start with the half-life (t 1/2
) corresponding to your personal scientific risk beliefs; or just trust the government and use EPA standard of 103.5 days. Recall that a longer
half-life assumes a more conservative
risk, while a shorter half-life means less risk aversion, believing the material will degrade sooner.
Using an initial quantity of 100 N0
, choose a desired quantity remaining based off your risk tolerance. For instance, 95% gone would mean 5% toxic gick remaining, (Nt
= 5). The remaining 4th field will give you the time to get to that amount (in this instance, in days). Make sense?
Another converter calculator
can then help put the days into better perspective.
In this example, you would want to wait 1 Year, 2 Months and 3 Weeks for 5% of the toxic gick to remain using EPA standards
A super risk-adverse person using a half life of 533 days, and only 1% remaining, on the other hand, would end up waiting 9 Years, 8 Months, 1 Week, and 5 Days.
But let's put math aside and just go with the politics
of the word. If you are referring to "organic" in the US government-owned official marketing
meaning of the work, follow their National Organic Program standards
. In that case, the answer
you're looking for is likely 3 years.