One more thing to note. Triazines are also affected by soil pH. They become more mobile and persistent in alkaline soils vs acid soils. 2 lb simazine is rather hot on pH 7.5 soil. Atrazine can become unusable, too much risk to surrounding trees. I know someone who cooked trees growing in the lawn with simazine. No, he was not a jackwagon that could not do math. It was because the herbicide leached down in alkaline soil.
They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety.
Benjamin Franklin 1775
Sell not virtue to purchase wealth, nor Liberty to purchase power.
Benjamin Franklin Poor Richard's Almanac1738