Fig. 5
NT generally had a positive effect on SOC concentration regardless of
experimental conditions, but especially under high MAT (> 6
℃), low MAP (< 500 mm), and continuous cropping patterns,
which significantly increased SOC concentration compared to CT by
24.1%, 43.9%, and 17.4%, respectively (Fig. 5). Similar to NT, RT and
ST also had a generally positive effect on SOC concentration, but the
degree of ascension was not often as great as NT.
With the increase of MAT, the effects of SOC under NT and ST increased
significantly (P < 0.05). Under high MAT (> 6 ℃)
ST and NT showed a large increase in SOC concentration compared to CT
(22.3% and 24.1%, respectively), but when MAT was lower than 6 ℃, the
effect size decreased and ST even had a negative effect (-1.2%) at 0 –
3 ℃ (Fig. 5a). When MAP < 500mm, NT had a significant higher
(P < 0.05) effect value than in more humid areas (MAP
> 500 mm) (Fig. 5b). Under continuous cropping, NT had a
significantly higher value (P < 0.05) than under a rotational
pattern, while the improvement in SOC under RT was not affected by the
type of cropping pattern employed (Fig. 5c). Time had no significant
impact on SOC for NT or ST treatments, although SOC concentration under
RT increased in longer duration experiments, increasing significantly (P
< 0.05) from 0.1% to 4.1% greater than CT (Fig. 5d).