What does it mean to add soil to the grave in the Gregorian calendar on auspicious days?

Adding soil to the grave is an important content of grave sweeping in Qingming Festival.

In the Ming Dynasty's "Scenery of the Imperial Capital", it was written: "On the Qingming Day in March, men and women went to the grave to pay their respects, and the gold ingots were hung on the back of the sedan chair, and the road was full of embarrassment. Worshippers, mourners, weeping, weeding and adding soil to the grave, burning gold ingots and putting paper money on the grave every time. "

Although "adding soil" is usually symbolic, there are also many stresses.

For example, the new grave cannot be filled for three years, which is said to be unfavorable to future generations.

For another example, when Tim Tu visited the grave in Tomb-Sweeping Day, he would check the Gregorian calendar at other times.