There is a park I know in the city adjacent to a kindergarten, an elementary school, a juior high school and a senior high school all next to each other, with high-rise apartments all around. It's a totally planned subdivision sleeper community.
The park features an artificial stream and pond inhabited by turtles. There is also a patch of terraced rice paddies, called "tambo" in Japanese. Every spring the paddies are flooded and planted. The rice grows quickly during the spring and summer, and in autumn it is harvested and dried on racks erected right there in the park.
First of all - who does this? I figure either (a) retired people in the commuity as a hobby or club; or (b) volunteer farmers as a teaching service for local children; or (c) volunteer retired farmers as a hobby and as a teaching service.
Secondly - why is it being done? It could just be a hobby of (a), (b), or (c) above. But I have always thought it was done for the educational benefit of the kindergarteners and primary schoolers, so that they could see and learn how and where their rice comes from. Also, it's just plain fun to watch how it's done.
In the park where these pictures are taken everything is done by hand, but the last picture in this sequence shows the usual way of cultivating rice on a modern farm.