3 ms·

> Neonicotinoids have a half life of 5 years and we spray fields EVERY YEAR. So it’s building up in the supply chain. Have they been in use less than 10 years?

> Neonicotinoids have a half life of 5 years and we spray fields EVERY YEAR. So it’s building up in the supply chain. Have they been in use less than 10 years? Or are we increasing the usage every year? Otherwise your conclusion doesn't seem to follow.

at_a_remove 5y ago
Okay, so with a half-life of five years, whatever you spray at year zero, you get about 87.0551% left by next year. So, let's imagine we spray just one unit per year. Year zero, one unit. Farmer Brown shows up to do his usual one-unit blast, recommended by Monsanto, but 87% of the stuff is still there. Year two, 1.870551 units are present. Year three, 2.628408673 units. Year four, 3.288162485. By year ten, you have 5.79376654 units present. If the half-life is really five years, you should do an initial one-unit dump, then just thirteen percent of that every subsequent year.
- RandallBrown 5y ago
  Presumably most of the pesticides get removed when the plants are harvested. Some probably are still around, but if spraying less worked, the farmers would because it would be cheaper. Not saying that pesticides aren't a problem, just saying that we're probably not just flooding our fields with more and more pesticides.
  - sjwalter 5y ago
    > the farmers would because it would be cheaper As a person who just became a farmer at the start of covid, I think this is a mistaken conclusion. Farmers are, in general, not out there a/b testing concentrations of herbicides or pesticides in their fields to find the exactly optimal level. If they're anything like most of the farmers I've met--who are absolutely really smart, well-intentioned folks--they talk to the guy at the extension office or weed control office and that guy tells them what to mix and how to apply. If it works, the farmer is generally happy. If not, he'll complain. The definition of "works" is: the immediate problem is solved. So the extension office guy, who usually seems to be indirectly funded by Dow Chemical in some way, or just by chance seems to really love that concern's range of products, is motivated to maybe overshoot a little. On my farm, we're doing things a little bit, uh, differently. Our food is expensive, but it's helping heal our soil and provides actual nutrition. https://mulligan.farm https://mulligan.farm.
- refurb 5y ago
  A quick scan says half-life can be up to 5 years, but also low as several days.
Sharlin 5y ago
I don't think half-life means what you think it means. A substance with a half-life of five years will not be gone in ten years.
- gizmondo 5y ago
  I know what it means, I was too lazy to do the math properly. The point was that with such a (relatively) short half-life the total amount stabilizes quickly.
  - kbelder 5y ago
    Once you've hit the balance, you'll have saturation equal to 1 + 4/5 + 16/25 + 64/125 ... It ends up summing to 5 (what a coincidence!). So 1 dose with a halflife of 5 years, applied yearly, hits equilibrium at 5x concentration.

at_a_remove 5y ago

Okay, so with a half-life of five years, whatever you spray at year zero, you get about 87.0551% left by next year. So, let's imagine we spray just one unit per year. Year zero, one unit. Farmer Brown shows up to do his usual one-unit blast, recommended by Monsanto, but 87% of the stuff is still there. Year two, 1.870551 units are present. Year three, 2.628408673 units. Year four, 3.288162485. By year ten, you have 5.79376654 units present. If the half-life is really five years, you should do an initial one-unit dump, then just thirteen percent of that every subsequent year.

RandallBrown 5y ago
Presumably most of the pesticides get removed when the plants are harvested. Some probably are still around, but if spraying less worked, the farmers would because it would be cheaper. Not saying that pesticides aren't a problem, just saying that we're probably not just flooding our fields with more and more pesticides.
- sjwalter 5y ago
  > the farmers would because it would be cheaper As a person who just became a farmer at the start of covid, I think this is a mistaken conclusion. Farmers are, in general, not out there a/b testing concentrations of herbicides or pesticides in their fields to find the exactly optimal level. If they're anything like most of the farmers I've met--who are absolutely really smart, well-intentioned folks--they talk to the guy at the extension office or weed control office and that guy tells them what to mix and how to apply. If it works, the farmer is generally happy. If not, he'll complain. The definition of "works" is: the immediate problem is solved. So the extension office guy, who usually seems to be indirectly funded by Dow Chemical in some way, or just by chance seems to really love that concern's range of products, is motivated to maybe overshoot a little. On my farm, we're doing things a little bit, uh, differently. Our food is expensive, but it's helping heal our soil and provides actual nutrition. https://mulligan.farm https://mulligan.farm.
refurb 5y ago
A quick scan says half-life can be up to 5 years, but also low as several days.

Sharlin 5y ago

I don't think half-life means what you think it means. A substance with a half-life of five years will not be gone in ten years.

gizmondo 5y ago
I know what it means, I was too lazy to do the math properly. The point was that with such a (relatively) short half-life the total amount stabilizes quickly.
- kbelder 5y ago
  Once you've hit the balance, you'll have saturation equal to 1 + 4/5 + 16/25 + 64/125 ... It ends up summing to 5 (what a coincidence!). So 1 dose with a halflife of 5 years, applied yearly, hits equilibrium at 5x concentration.