Assalamu alaikum wa rehmatullahi wa barakatuh
And (in) the differences between the night and the daytime, and whatever provision Allah sends down from the heaven, so He gives life therewith to the earth after its death, and the (constant) turning about of the winds, there are signs for a people who consider.(45:5)
1.The soil has number of Living organisms in it and the ecosystem is known as soil ecosystem.
The Ecosystem respiration is directly proportional to soil moisture i.e. the amount of precipitation.Read here.
2.The rain does not only contain water but many other components too,all nourishing the soil ecosystem.
So the rain water consisting of many minerals and compounds,actually revives the soil ecosystem,which is consisting of many living organisms.