Table 1.
Physical and chemical properties of the 0–40 cm soil profile at the experimental site.
Table 2.
Sequence of soil rotational tillage system from 2009 to 2012.
Table 3.
Mean soil bulk density (BD), pH, soil organic carbon (SOC), and available N, P and K in the 0–40 cm soil depths under different treatments at the maturity stage of winter wheat and summer maize in 2012.
Table 4.
Repeated measures ANOVA P value for the effects of treatment (T), crop growth stage (G), soil depth (D), and their interactions on soil invertase activity, urease activity, alkaline phosphatase activity and catalase activity.
Fig 1.
Invertase activity in the soil layers at 0–10 cm (a), 10–20 cm (b), 20–30 cm (c) and 30–40 cm (d) under different treatments during the winter wheat and summer maize seasons of 2012.
Within each growth stage, the bars with different lowercase letters are significantly different at P < 0.05 according to the LSD test. 3RT, 3 years of RT to a depth of 10–15 cm; 3PT, 3 years of PT to a depth of 30–35 cm; PT+2RT, 1 year of PT followed by 2 years of RT; and 2PT+RT, 2 years of PT followed by 1 year of RT.
Fig 2.
Urease activity in the soil layers from 0–10 cm (a), 10–20 cm (b), and 20–30 cm (c) and 30–40 cm (d) under different treatments during the winter wheat and summer maize seasons of 2012.
Within one growth stage, bars with different lowercase letters are significantly different at P < 0.05 according to the LSD test. 3RT, 3 years of RT to a depth of 10–15 cm; 3PT, 3 years of PT to a depth of 30–35 cm; PT+2RT, 1 year of PT followed by 2 years of RT; and 2PT+RT, 2 years of PT followed by 1 year of RT.
Fig 3.
Alkaline phosphatase activity in soil layers from 0–10 cm (a), 10–20 cm (b), and 20–30 cm (c) and 30–40 cm (d) under different treatments during the winter wheat and summer maize seasons of 2012.
Within one growth stage, bars with different lowercase letters are significantly different at P < 0.05 according to the LSD test. 3RT, 3 years of RT to a depth of 10–15 cm; 3PT, 3 years of PT to a depth of 30–35 cm; PT+2RT, 1 year of PT followed by 2 years of RT; and 2PT+RT, 2 years of PT followed by 1 year of RT.
Fig 4.
Catalase activity in the soil layers at 0–10 cm (a), 10–20 cm (b), and 20–30 cm (c) and 30–40 cm (d) under different treatments during the winter wheat and summer maize seasons of 2012.
Within each growth stage, bars with different lowercase letters are significantly different at P < 0.05 based on the LSD test. 3RT, 3 years of RT to a depth of 10–15 cm; 3PT, 3 years of PT to a depth of 30–35 cm; PT+2RT, 1 year of PT followed by 2 years of RT; and 2PT+RT, 2 years of PT followed by 1 year of RT.
Table 5.
Mean of soil quality index (SQI) at the 0–40 cm soil depths under different tillage treatments at the maturity of winter wheat and summer maize in 2012.
Table 6.
Changes in grain yield of winter wheat and summer maize under different treatments in 2012.