Nepal, Aug. 25 -- A simple change in traditional irrigation methods could cut methane emission, save water, and create a new source of carbon credits for rural economies in Nepal. But making it work will require coordination, monitoring and fair distribution of the revenue.

Flooded rice fields are a familiar sight across Nepal. Keeping the paddy plant underwater controls weeds, but in the absence of oxygen, methane-producing microbes thrive in the soil. Methane is an even more potent greenhouse gas than carbon dioxide and makes up a significant source of Nepal's agricultural carbon emissions.

A simple modification of farming practice could help change this. Alternate wetting and drying (AWD) allows rice fields to dry briefly instead of...