The harvester represents the most expensive and efficient farming machinery available in 3rd World Farmer. Each one provides an extra +100% revenue from crops harvested. The bonus, which is cumulative with other tools bonuses, can be seen on the annual report.
The Angry Mob event causes the player to lose all his tools, including any harvesters.
A visit from Guerillas will cost the player all harvesters (as well as livestock and tractors), unless he has completed the representative project.
In the event of a Civil War there’s a 75% risk that each owned harvester will be destroyed in the conflict.
WikiPedia on Mechanised agriculture and agricultural machinery:
“Potato Farmers in Kenya turn to mechanization to meet rapidly increasing demand,” Food Innovation Online Corps, 2016:
“The Age of Robot Farmers” by John Seabrook, The New Yorker, 2019: