Table 2 Mean values of soil nutrients in three sampling years (2001, 2006, and 2015, respectively).

2001

N

1.90 ± 0.25

0.789 ± 0.01

23.95 ± 1.15

36.41 ± 6.23

0.30 ± 0.05

3.14 ± 0.82

0.96 ± 0.36

W

2.17 ± 0.13

0.885 ± 0.01

24.61 ± 0.0.45

36.23 ± 6.71

0.33 ± 0.06

3.32 ± 0.60

0.91 ± 0.20

S

2.05 ± 0.13

0.809 ± 0.01

25.36 ± 0.50

37.91 ± 5.55

0.39 ± 0.07

3.64 ± 0.83

0.95 ± 0.27

D

2.41 ± 1.15

0.993 ± 0.01

24.36 ± 0.14

45.35 ± 10.50

0.47 ± 0.09

4.15 ± 0.93

0.94 ± 0.24

2006

N

1.82 ± 0.29

0.692 ± 0.01

25.20 ± 1.12

38.48 ± 7.83

0.28 ± 0.06

2.61 ± 0.73

0.87 ± 0.32

W

2.01 ± 0.16

0.723 ± 0.01

27.89 ± 1.33

41.96 ± 5.18

0.34 ± 0.02

3.40 ± 0.85

1.09 ± 0.25

S

2.04 ± 0.21

0.740 ± 0.01

26.99 ± 1.42

37.71 ± 1.79

0.30 ± 0.08

2.93 ± 1.02

0.75 ± 0.25

D

1.99 ± 0.32

0.740 ± 0.01

27.20 ± 1.25

42.71 ± 8.02

0.35 ± 0.06

2.93 ± 0.56

0.97 ± 0.23

2015

N

1.49 ± 0.24

0.608 ± 0.01

25.12 ± 1.59

41.03 ± 9.91

0.43 ± 0.08

3.53 ± 0.87

1.11 ± 0.30

W

1.73 ± 0.22

0.629 ± 0.01

26.40 ± 0.70

46.71 ± 6.54

0.29 ± 0.05

2.80 ± 0.38

0.86 ± 0.12

S

1.82 ± 0.22

0.700 ± 0.01

26.29 ± 0.83

47.23 ± 4.43

0.26 ± 0.06

3.14 ± 0.90

0.88 ± 0.30

D

2.03 ± 0.25

0.786 ± 0.01

25.85 ± 1.22

50.74 ± 13.10

0.33 ± 0.05

2.97 ± 0.73

1.03 ± 0.28