He asked an official to what extent the atmospheric temperature went down in this area colder than Pyongyang.

The official said that the temperature fell down to 22 degrees C below zero, and according to the experience in greenhouse farming for several years, it was possible to solve the problem of low atmospheric temperature but the low soil temperature caused by the high water level had bad influence on the vegetable cultivation.

After being wrapped in thought for a while, the President said that if the vegetable production was badly influenced by the low soil temperature of the greenhouse, they should dig ditches in front and in the rear of the greenhouse, which might prevent the soil temperature from going down in winter.

His words awakened the officials.

In fact, they were plagued by the low soil temperature in the winter vegetable cultivation.

The President found instantly a way out for overcoming it.

The instructions of the President on digging ditches in the front and in the rear of the greenhouse and lowering the underground water level below the greenhouse were a capital idea that made it possible to put the winter vegetable cultivation on a normal track.

That day, the President instructed officials that the brook in the rear of the greenhouse should be dug two meters deep.