Did you go to high school in the country that made this law? In addition, how many farmers in that country get high school education?

From what I read getting grades 1-8 is common in Kenya, but the high school years of education drop off significantly with only around 40% of the population getting that education, and making an educated guess that would target city people more than those that would be farmers.

https://en.wikipedia.org/wiki/Education_in_Kenya

Poor education doesn't make it new knowledge.

If anyone was taught this in highschool, it must have been established practice for decades at least.