Long-term Fertilization and Mineralization of Soil Organic Carbon in Paddy Soil from Yellow Earth
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Supported by the National Natural Science Foundation of China (Nos. 31360503 and 41361064), the Project of National Engineering Laboratory for Improving Quality of Arable Land (No. 201701) and Graduate Innovation Fund of Guizhou University (No. 2017017)

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    Abstract:

    【Objective】As a basic biochemistral process in the terrestrial ecosystem, mineralization of soil organic carbon (SOC) is closely related to release of soil nutrients, maintenance of soil quality, and formation of greenhouse gases. Fertilization is one of the most important factors influencing of SOC mineralization. The objective of this study is to explore dynamics of SOC mineralization in paddy soil from yellow earth as affected long-term fertilization, illuminate characteristics of organic carbon mineralization in paddy fields of yellow soil different in fertilization and provide guidance for formulating reasonable nutrient management programs.【Method】Analysis of the data of the 22-year long-term stationary fertilization experiment in paddy soil from yellow earth in the Guizhou Academy of Agricultural Sciences, was done for effect of long-term fertilization on SOC mineralization in the paddy soil, and meanwhile an in-lab incubation experiment was conducted. The field experiment was designed to have five fertilization treatments: CK (no fertilizer), Treatment NPK (application of chemical fertilizer), Treatment 0.5MNPK (application of chemical fertilizer, half the rate, plus organic manure), Treatment M (application of cow dung) and Treatment MNPK (application of NPK, normal in rate, plus organic manure ).【Result】After 22 years of fertilization the SOC content was 22.8 g kg-1 in CK and 21.6 g kg-1 in Treatment NPK, and increased by 30.6%, 72.9% and 62.2%, in Treatments 0.5MNPK, M and MNPK, respectively. Obviously the increase was particularly remarkable in Treatments M and MNPK (p < 0.05). In the in-lab incubation experiment, it was found that CO2 production rate reached a peak on D2, fell rapidly till D4, declined gradually until D24, and leveled off D30. In terms of SOC mineralization rate the five treatments exhibited an order of M > MNPK > 0.5MNPK > CK > NPK. The relationships between mineralization rates of SOC and duration of incubation in all the treatments fit the logarithmic function equation (p < 0.01). The cumulative SOC mineralization on D30 varied in the range of 1.23 g kg-1 to 2.37 g kg-1. Compared with CK treatment (1.46 g kg-1), Treatment M and MNPK increased significantly or by 62.6% and 44.2%, respectively in cumulative SOC mineralization (p < 0.05). But all the treatments were lower than CK (6.4%) in ratio of cumulative SOC mineralization to total SOC after 30 days of incubation, especially Treatments M and MNPK treatments decreasing by 1.2% and 0.9%. The dynamic variation of the cumulative SOC mineralization with incubation time fit the first-order kinetics equation (p < 0.01). The simulation results show that soil potential mineralizable organic carbon was 1.15 g kg-1 CK decreased insignificantly or by 11.6% in Treatment NPK, but increased in Treatments 0.5MNPK, M and MNPK by 21.3% ~ 73.6%. The increase was the most significantly in Treatments M and MNPK (p < 0.05). At the same time, Treatment MNPK increased SOC turnover rate and reduced turnover time. 【Conclusion】In conclusion, long-term application of organic manures, like in Treatments 0.5MNPK, M and MNPK, can improve SOC mineralization rate, promote SOC accumulation, reduce SOC cumulative mineralization ratio (mineralization level per unit organic carbon), and enhance soil C sequestration capacity.

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GUO Zhen, WANG Xiaoli, DUAN Jianjun, JIAO Keqiang, SUN Shasha, DUAN Yinghua, ZHANG Yarong, LI Yu, JIANG Taiming. Long-term Fertilization and Mineralization of Soil Organic Carbon in Paddy Soil from Yellow Earth[J]. Acta Pedologica Sinica,2018,55(1):225-235.

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History
  • Received:May 26,2017
  • Revised:July 12,2017
  • Adopted:July 21,2017
  • Online: October 30,2017
  • Published: