Why don't they plant cacti on a large scale in the desert?

The purpose of greening is not to look green, but to stabilize soil and water, and cacti cannot achieve the effect of stabilizing soil and water.

Cacti are native to the tropics and subtropics of North and South America. Most of China's deserts are in the north, where winters are cold, and cacti simply cannot survive. Moreover, although cacti have tenacious vitality, surviving in a special environment like the desert is still very difficult. And truly planting large areas of desert by hand is a very difficult task, not as easy as imagined; especially at night, when sandstorms appear, not to mention cacti, even people are in danger. So this is an unrealistic practice.

Moreover, cacti cannot change the soil structure or anything like that. It is enough to protect the local lichens and shrubs, save agricultural water, and let seasonal rivers flow on. To truly green the desert at its root, it would be necessary to change the current climate pattern and increase the precipitation in this region.