Fig 1.
(a) Monthly distribution of average temperature and total precipitation, and (b) annual total precipitation in growing seasons (May-August) and off growing season in 1988–2016.
Fig 2.
Illustration of the simulation experiments studying the impact of tillage treatments and climate change, considering climate scenarios and precipitation variability at crops’ early and late stages, on the yields of maize and wheat and SOC of the maize-soybean-wheat rotational cropping system.
Table 1.
Descriptions of the climate scenarios in the study.
Fig 3.
Comparisons between the simulated and the observed grain yield in the maize-soybean-wheat rotation system under (a) conventional (CT) and (b) no-till (NT) treatments at the Kellogg Biological Station in 1989–2016.
Fig 4.
Comparisons between simulated SOC changes in 1989–2006 and observed change in 1988–2006 in the maize-soybean-wheat rotation system under conventional (CT) and no-till (NT) treatments at the Kellogg Biological Station (the observation was from [43]).
Fig 5.
Distribution of the simulated maize grain yield under conventional (CT) and no-till (NT) treatments in the simulated 24 years under the nine climate treatments that combines three greenhouse gas concentration paths scenarios (historical, RCP4.5 and RCP6) and three precipitation frequency scenarios (no changes in precipitation frequency (N/A), and drought and heavy rainfall imposed for early or late growth stage) (p values are from the two-way ANOVA analysis; the top and the bottom of the box represent the first and the third quartile values, respectively; the line within the box presents the median value; the top and the bottom ends of the whiskers represent the maximum and the minimum values, respectively; the circle represents the mean value).
Fig 6.
Distribution of the simulated wheat grain yield under conventional (CT) and no-till (NT) treatments in the simulated 24 years under the nine climate treatments that combines three greenhouse gas concentration paths scenarios (historical, RCP4.5 and RCP6) and three precipitation frequency scenarios (no changes in precipitation frequency (N/A), and drought and heavy rainfall imposed for early or late growth stage) (p values are from the two-way ANOVA analysis; the top and the bottom of the box represent the first and the third quartile values, respectively; the line within the box presents the median value; the top and the bottom ends of the whiskers represent the maximum and the minimum values, respectively; the circle represents the mean value).
Fig 7.
(a) Average SOC across the six replicates under the two treatments, conventional tillage (CT) and no-till (NT), during the simulated 28 years for historical, RCP4.5 and RCP6 climates; (b) Average and standard deviation of SOC loss in the simulated 28 years under conventional treatment; (c) Average and standard deviation of SOC gain in the simulated 28 years under no-till treatment (bars represent the standard deviation values; climate scenarios sharing the same letter are not significantly different at P = 0.05 using Tukey’s honestly significant difference test).
Fig 8.
Average and standard deviation of the simulated maize yield with and without climate adaptation strategies under conventional tillage (CT) and no-till (NT) in the 24 years for various projected climate scenarios: (a-b) RCP4.5 and RCP6 climate without changing precipitation frequency, (c-d) RCP4.5 and RCP6 climate combined with changing precipitation frequency at maize and wheat early growth stage, (e-f) RCP4.5 and RCP6 climate combined with changing precipitation frequency at maize and wheat late growth stage (error bars represent the standard deviation; adaptation strategies sharing the same letter are not significantly different at P = 0.05 using Tukey’s honestly significant difference test within the tillage treatment).
Fig 9.
Average and standard deviation of the SOC with and without climate adaptation strategies under conventional tillage (CT) and no-till (NT) in the 28 years for various scenarios: (a-b) RCP4.5 and RCP6 climate without changing precipitation frequency, (c-d) RCP4.5 and RCP6 climates combined with changing precipitation frequency at maize and wheat early growth stage, (e-f) RCP4.5 and RCP6 climate combined with changing precipitation frequency at maize and wheat late growth stage (error bars represent the standard deviation; adaptation strategies sharing the same letter are not significantly different at P = 0.05 using Tukey’s honestly significant difference test within the tillage treatment).