I don't know what you mean by "qualifications" but growing rice efficiently does need technology to control the water level in the rice paddies, and if you want to grow rice in a hilly region, you need to terrace the landscape to contain the standing water required.
On the other hand growing wheat and corn was pretty much a matter of "sow the seed and wait till harvest time," in early agriculture. Of course you needed to know when to plant (for which astronomy was useful!) but once discovered, using that knowledge didn't require any "technology" beyond naked-eye observations of the stars.
Technology does enter into cereal growing to convert the grain into flour, once laborious hand-milling by individual families is replaced by wind or water mills, which were the "high tech engineering" of their day. But operating and constructing mills were a specialist occupations separate from "farming," and unlike farming were not labour-intensive, in the sense that one miller could process the output of hundreds of farm workers.