长期施肥对潮土玉米碳含量及分配比例的影响

【目的】研究不同施肥措施对潮土玉米植株碳同化物积累与分配的影响,为合理施肥和作物增产提供科学依据。【方法】以长期定位试验为基础,在玉米成熟期进行取样分析,研究不同施肥下玉米植株及器官的碳含量、碳同化物分配比例及碳氮比。【结果】长期有机无机配施(NPKM,1.5NPKM)下植株碳含量平均约为464g·kg-1,比偏施氮肥(N)与偏施磷钾肥(PK)处理的碳含量提高了3%左右。PK处理的碳同化物在茎叶中的分配比例约为57%,比最低的N处理高出了73%;在根茬中,PK处理的碳同化物分配比例也最高,高出N处理约为7%。但在籽粒中,PK处理的碳同化物分配比例最低,为30%。茎叶、穗轴、根茬的碳氮比,以PK处理为最高,1.5NPKM处理最低,前者比后者分别高121%、105%和120%。所有施肥处理中,玉米地上部分固碳量为NPKM处理最高,比CK处理高7.2t·hm-2;地下部分固碳量则以NPK处理平衡施肥最高,比CK处理高0.3t·hm-2。【结论】NPK配施及有机-无机肥配施能有效提高玉米植株的固碳量,提高碳同化物在玉米植株籽粒和穗轴中的分配比例,从而降低碳同化物在茎叶和根茬中的分配比例及其C/N,对土壤培肥和碳固定具有双重作用,是可持续和环境友好型的施肥模式。

Effects of Long-Term Fertilization on Assimilated Carbon Content and Distribution Proportion of Maize in Fluvio-Aquic Soil

【Objective】 Study on the assimilated carbon accumulation and distribution of maize under various fertilizer applications in fluvio-aquic soil, can not only provide a scientific basis for rational fertilization practices for increasing crop yield, but it also has important significance to the study of global carbon cycling. 【Method】 Based on a long-term experiment, samplings from various organs of maize were taken at maturity stage to measure the biomass yield under various fertilization applications. Organic carbon content, carbon assimilate distribution proportion, and C/N ratio of maize and its various organs under different fertilization conditions were also analyzed. 【Result】 The results showed that the averaged carbon content in maize was about 464 g?kg-1 under the long term combined application of fertilizers and organic manure (NPKM, 1.5NPKM). It was 3% higher than the applications of N and PK treatments. The carbon content of maize kernel was obviously improved in the NK treatment, which was about 3% higher than the control treatment. In all treatments, the distribution proportion of assimilated carbon biomass in stem and leaf of maize was about 57% in PK treatment, which was 73% higher than that of the N treatment. The distribution proportion of assimilated carbon biomass in crop stubble in the PK treatment was also the highest (about 7%). The distribution proportion of assimilated carbon biomass in maize grain under the PK treatment was the lowest (30%). The C/N ratio in maize stem and leaf, cob, and crop stubble was the highest in PK treatment whereas it was the lowest under the 1.5NPKM treatment. The C/N ratio in stem and leaf, cob, and crop stubble in PK treatment was 121%, 105% and 120% higher than that in the 1.5NPKM treatment, respectively. In all fertilization treatments, the fixed carbon content in whole maize was the highest in NPKM treatment in above-ground parts of maize, and that was the highest in NPK balanced fertilization treatment in under-ground parts of maize. The fixed carbon content of maize in the above-ground part in NPKM treatment was about 7.2 t?hm-2 higher than that of the control treatment, NPK balanced fertilization treatment was 0.3 t?hm-2 higher than that of the control treatment for the under-ground part of maize. 【Conclusion】 The combined NPK fertilization and organic-inorganic fertilization significantly enhanced the carbon biomass of crop. These balanced fertilizations improved the distribution proportion of assimilated carbon in grain and cob, and then reduced the distribution proportion of assimilated carbon and the C/N ratio in stem and leaf, and crop stubble. These changes in distribution proportion of assimilated carbon and the C/N ratio by the balanced fertilization were helpful for the decomposition and transformation of returned straw and crop stubble into the soil. It indicates that balanced fertilization is a sustainable and environment-friendly management practice and has great significance for soil fertility and soil carbon sequestration.