LONG AN, Vietnam (AP) — There is one thing that distinguishes 60-year-old Vo Van Van’s rice fields from a mosaic of thousands of other emerald fields across Long An province in southern Vietnam’s Mekong Delta: It isn’t entirely flooded.

That and the giant drone, its wingspan similar to that of an eagle, chuffing high above as it rains organic fertilizer onto the knee-high rice seedlings billowing below.

Using less water and using a drone to fertilize are new techniques that Van is trying and Vietnam hopes will help solve a paradox at the heart of growing rice: The finicky crop isn’t just vulnerable to climate change but also contributes uniquely to it.

Rice must be grown separately from other crops and seedlings have to be individually planted in flooded fields; backbreaking, dirty work requiring a lot of labor and water that generates a lot of methane, a potent planet-warming gas that can trap more than 80-times more heat in the atmosphere in the short term than carbon dioxide.