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Table 3 Effect of tillage and cropping sequence combination on soil Olsen-P, K, and SO4–S concentrations at the 0–120 cm depth in 2013

From: Dryland soil chemical properties and crop yields affected by long-term tillage and cropping sequence

Tillage and cropping sequencea

Soil depth

0–7.5 cm

7.5–15 cm

15–30 cm

30–60 cm

60–90 cm

90–120 cm

Olsen-P concentration (mg P kg−1)

 NTCW

36.8abAc

2.8B

2.3B

2.0B

2.3B

3.3B

 STCW

40.0aA

5.5B

2.0C

2.0C

2.0C

2.0C

 FSTCW

34.3aA

3.0B

2.3B

2.0B

2.1B

3.3B

 FSTW-B/P

36.6aA

6.0B

2.1C

2.1C

1.9C

2.6C

 STW-F

25.0bA

4.9B

3.3BC

2.0C

2.2B

2.6BC

 Contrast

  NT vs. T

−0.4

−1.5

0.1

0.1

0.3

0.7

  CW vs. W-F

15.0***

0.63

−1.3*

0.1

−0.2

−0.6

  CW vs. W-B/P

−2.4

−3.6*

0.1

−0.1

0.2

0.7

K concentration (mg K kg−1)

 NTCW

331aA

279aB

157C

96D

91D

105D

 STCW

331aA

228B

179B

112C

98C

96C

 FSTCW

325abA

263aB

150C

97D

91D

100D

 FSTW-B/P

348aA

242aB

149C

103C

102C

115C

 STW-F

272bA

186bB

129C

93C

98C

95C

 Contrast

  NT vs. T

3.0

6.5

−7.0

−8.9

−3.1

6.9

  CW vs. W-F

58.1*

96.6**

49.6*

18.4*

0.1

1.0

  CW vs. W-B/P

−23.9

21.5

0.4

−5.3

−11.5

−15.6

SO4–S concentration (mg SO4–S kg−1)

 NTCW

6.8A

3.5A

3.0A

3.0A

4.3A

5.0bA

 STCW

6.3A

3.5A

3.0A

3.3A

4.8A

5.8bA

 FSTCW

6.0B

3.5B

3.3B

4.3B

10.5AB

26.5aA

 FSTW-B/P

12.8B

11.0B

11.8B

12.3AB

21.0A

23.9aA

 STW-F

8.0A

8.1A

7.5A

10.4A

11.4A

11.8bA

 Contrast

  NT vs. T

0.6

0.1

−0.1

−0.8

−3.4

−11.3*

  CW vs. W-F

−1.8

−4.6

−4.5

−7.1

−6.6

−6.0

  CW vs. W-B/P

−6.8

−7.5

−8.5

−8.0

−10.5

2.6

  1. NTCW no-till continuous spring wheat, STCW spring till continuous spring wheat and STW-F spring till spring wheat-fallow. CW continuous wheat, NT no-till, T till, W–B/P spring wheat–barley/pea and W-F spring wheat-fallow.
  2. *, **, and *** Significant at P = 0.05, 0.01, and 0.001, respectively.
  3. aTillage and cropping sequence are FSTCW fall and spring till continuous spring wheat, FSTW–B/P fall and spring till spring wheat–barley (1994–1999) followed by spring wheat–pea (2000–2013).
  4. bNumbers followed by different lowercase letters within a column among treatments in a set are significantly different at P ≤ 0.05 by the least square means test.
  5. cNumbers followed by different uppercase letters within a row among soil depths in a set are significantly different at P ≤ 0.05 by the least square means test.