5 factors of soil formation

7:42

9:28

5:11

6:56

29:41

2:05

38:12

4:30

22:10

30:49

18:11

13:41

6:01

25:59

3:47

3:33

3:11

4:34

44:10

1:36

15:29

13:51

7:13

12:38

41:13

16:32

1:15

37:03

3:29

44:55

21:17

7:24

10:03

6:10

15:57

20:03

4:58

17:15

2:16

11:08

27:46

56:01

1:59:50

2:04

3:03

32:36

16:06

53:00

12:45

33:46

11:57

7:31

2:42

2:54

20:51

5:28

56:44

12:45

1:22

15:52