The South Korean government’s historical efforts to introduce improved crop varieties have been ambiguously successful. State-bred rice varieties helped achieve national food production goals during the Green Revolution of the 1970s, but these varieties were highly unpopular and were abandoned soon, as the government stopped promoting them. This paper contrasts that experience with the simultaneous successful introduction of an improved variety of tangerine as a cash crop in Jeju Province. Smallholders of Jeju found space for the high-return fruit in the (...) existing land use system, including the partial conservation of agrobiodiversity without critically risking their subsistence-based food security. Citrus in general was a spatially less-demanding crop that farmers could partly co-cultivate with subsistence crops, while state-bred rice varieties occupied farmland exclusive of other varieties and rice’s double crops. Additionally, by employing political ecology, this paper asserts that the different roles of the state in introducing the two crops and the different regions were other factors behind such divergent adoption outcomes. Considering rice, the state was highly interventionist, because the government depended on rice-producing regions to “feed the nation”; with regard to non-staple-crop production in low-productivity, hard-to-develop regions like Jeju, in contrast, the government gave farmers more autonomy, thus allowing farmers to determine their own space and pace for citrus adoption. The study critically investigates the variable of spatial compatibility between a crop and the land system and sheds light on the current development mission to harmonize the cultivation of food and cash crops. (shrink)