Responses of soil respiration and soil organic carbon pools to temperature under long-term different straw returning amounts in wheat-maize rotation system
Soil samples were collected from 41-year experimental fields that have been continuously returning straws with different amounts including 0 kg/hm2(S1),2 250 kg/hm2(S2),4 500 kg/hm2(S3),and 9 000 kg/hm2(S4)and were incubated at 15,25 and 35℃for 125 d to investigate the responses of soil respiration and soil carbon pools in the wheat and maize rotation area of North China.The results showed that soil respiration rate showed a decreasing and then stable trend during the whole incubation period.The straw returning amount and temperature significantly affected the soil respiration rate and the cumulative soil respiration.Soil respiration rate and the cumulative soil respiration among treatments are generally exhibited on 35℃>25℃>15℃,S4>S3>S2>S1.The straw returning amount and temperature significantly affected soil organic carbon and its fractions.Soil organic carbon content in S4 treatment was significantly higher than that of other treatments.The contents of soil particulate organic carbon and microbial organic carbon in S3 and S4 treatments were significantly higher than that of other treatments.With the increase of incubation temperature,soil organic carbon and its fractions showed a decreasing trend.Soil respiration rate was positively correlated with soil organic carbon,particulate organic carbon,and microbial carbon content.Compared with S1 and S2,temperature sensitivity(Q10)significantly decreased in S3 and S4.In conclusion,long-term medium and high straw returning can improve soil organic carbon pool,decrease the temperature sensitivity of soil respiration,and lower the release of CO2 in wheat and maize rotation system in North China,and the medium straw returning has a higher potential and space for carbon sequestration under global warming conditions.
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