Through the test, he found out in a scientific way the growing period of strains for double cropping and their features and became convinced that grain and grain, grain and vegetables, grain and oil-bearing crops, and grain and feed crops were suitable for double cropping but grain and grain should take a large proportion of double cropping.

One October day in Juche 56 (1967) he summoned senior officials of the agricultural sector to his experimental fields.

Reaching an aftercrop bean field, he picked up a bean plant and checked pods, and plants and beans per phyong (one phyong=3.954 sq. yds).

He then told the officials that beans cropped well after barley.

Listening to his explanation, they were deeply moved by his effort for the country's agricultural development and his profound knowledge of double cropping.