If mud snails are let loose on rice fields more than a week after rice-transplanting, they eliminate sprouting weeds and their excrements increase the fertility of soil.

Mangyongdae District, Pyongyang, in an effort to introduce organic farming method in all its farms, has expanded the acreage of mud snail use five times and put mud snails on rice fields after rice-transplanting.

The Chilgol and Wollo farms have raised mud snails on ponds for rice fields, while giving farmers knowledge necessary in breeding and using them.

The Migok Cooperative Farm in Sariwon City, North Hwanghae Province, has built a large ground for feeding mud snails to dispense with much labor in weeding.

This method has also been applied by farms in Mundok County in South Phyongan Province, Yomju County in North Phyongan Province and Sinchon County in South Hwanghae Province.