Fig 1.
(a) Design drawing of pot experiment, (b) schedule of fertilization and irrigation managements and air temperature, and (c) photograph of the indoor experiment. SI: straw incorporation; S0: straw removal; BC: biochar addition; B0: without biochar.
Table 1.
Physicochemical properties of the surface soil and biochar.
Fig 2.
The emission fluxes of N2O and NH3 under conditions of either straw incorporation (a, b) and straw removal (c, d) with different addition amounts of biochar. Error bars denote standard errors. C0: without biochar; C1: biochar applied at 15 t ha−1; C2: biochar applied at 30 t ha−1; C3: biochar applied at 45 t ha−1.
Fig 3.
The influence of straw and biochar on N2O and NH3 emissions.
Error bars denote standard errors. * P<0.05. Definitions of C0, C1, C2, and C3 are given in caption of Fig 2.
Fig 4.
Soil temperature under different treatments during the experimental period.
Error bars denote standard errors. Definitions of C0, C1, C2, and C3 are given in caption of Fig 2.
Fig 5.
WFPS under different treatments during the experimental period.
Error bars denote standard errors. Definitions of C0, C1, C2, and C3 are given in caption of Fig 2.
Fig 6.
Soil NO3−−N, NH4+−N, total N, and organic matter content in different soil layers under different treatments.
Error bars denote standard errors. The different letters in the same soil layer indicate a significant difference (P<0.05) with Turkey’s multiple range test of different amounts of biochar addition either under straw incorporation or not. Definitions of C0, C1, C2 and C3 are given in caption of Fig 2.
Fig 7.
(a) Redundancy analysis of the influence and the contribution (b) of soil properties on N2O and NH3 losses.
Fig 8.
Correlation analysis between biochar addition, N2O, NH3, and measured variables under straw incorporation or removal.
Each bubble with * indicates a significant correlation at P<0.05.
Table 2.
Two-way ANOVA of the effects of straw incorporation (S) and biochar applied (C) on cumulative N2O emissions, cumulative NH3 volatilization, and soil moisture, NO3−−N, NH4+−N, total N (TN), soil organic matter (SOM) content, and pH in the 0−10 cm, 10−20 cm, and 20−40 cm soil layers.
Fig 9.
The relationship between overall N2O emission and biochar addition under straw incorporation (S1) and removal (S0).
Error bars denote standard errors.