Abstract
Straw return is a promising strategy for managing soil organic carbon (SOC) and improving yield stability.However,the optimal straw return strategy for sustainable crop production in the wheat (Triticum aestivum L.)-cotton (Gossypium hirsutum L.) cropping system remains uncertain.The objective of this study was to quantify the long-term (10 years) impact of carbon (C) input on SOC sequestration,soil aggregation and crop yields in a wheat-cotton cropping system in the Yangtze River Valley,China.Five treatments were arranged with a single-factor randomized design as follows:no straw return (Control),return of wheat straw only (Wt),return of cotton straw only (Ct),return of 50％ wheat and 50％ cotton straw (Wh-Ch) and return of 100％ wheat and 100％ cotton straw (Wt-Ct).In comparison to the Control,the SOC content increased by 8.4 to 20.2％ under straw return.A significant linear positive correlation between SOC sequestration and C input (1.42-7.19 Mg ha-1 yr-1) (P<0.05) was detected.The percentages of aggregates of sizes>2 and 1-2 mm at the 0-20 cm soil depth were also significantly elevated under straw return,with the greatest increase of the aggregate stability in the Wt-Ct treatment (28.1％).The average wheat yields increased by 12.4-36.0％ and cotton yields increased by 29.4-73.7％,and significantly linear positive correlations were also detected between C input and the yields of wheat and cotton.The average sustainable yield index (SYI) reached a maximum value of 0.69 when the C input was 7.08 Mg ha-1 yr-1,which was close to the maximum value (SYI of 0.69,C input of 7.19 Mg ha-1 yr-1) in the Wt-Ct treatment.Overall,the return of both wheat and cotton straw was the best strategy for improving SOC sequestration,soil aggregation,yields and their sustainability in the wheat-cotton rotation system.
维普
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