长期定位施肥对土壤的碳氮共济效应情景分析

碳氮共济的概念体现了二者间共同依赖、共同转化、共同协作的关系，将土壤碳和氮均作为改善土壤质量的主动因素，这一概念有别于其它碳氮关系论述时只考虑元素间的被动耦合机制。土壤碳和氮之间存在着相互依存和相互制约的关系，土壤碳、氮在数量上和结构上需要处于什么样的状态才能够实现土壤碳氮的共济关系，土壤碳对氮有多大的承载能力等是值得探讨的问题。文章利用我国长期定位试验中的土壤碳氮数据，分析土壤的碳氮质量分数变化特征、施肥对土壤w（C）/w（N）比的影响、土壤碳对氮素的储存能力、碳氮共济关系及其情景分析，以便为充分挖掘土壤碳氮的生物学潜力、提高土壤生产力、改善环境和实现碳氮的良性循环提供依据。通过检索文献数据库，选取了69篇记载有土壤碳氮数据的有代表性的文章，获得土壤碳氮数据1782项。分析结果表明：土壤碳氮关系可以用yC＝7.66xN＋1.8162（r2＝0.734＊＊, n=737）表达，土壤平均全氮质量分数为1.17 g·kg-1，变化范围在0.08~3.52 g·kg-1之间，土壤平均有机碳质量分数为10.8 g·kg-1，变化范围在0.64~32.08 g·kg-1之间；土壤w（C）/w（N）比集中在7.6~10.7之间，占总样本的80%左右，有机无机配施有利于提高土壤的w（C）/w（N）比，单施化肥，特别是偏施某一种化肥时，将显著降低土壤的w（C）/w（N）比；在土壤氮素储存率为N 20 kg·hm-2·a-1，目标w（C）/w（N）比为9、10、11的情景下，目前已经处于碳饱和的土壤分别占：52.7%、72.1%、87.5%；储存率为N 50 kg·hm-2·a-1的情景下分别占：58.2%、78.2%、91.4%；储存率为N 100 kg·hm-2·a-1的情景下分别占68.7%、87.6%、95.8%。土壤碳氮质量分数变异很大，总体碳氮比稳定在7.66左右，偏施化肥将显著降低土壤的w（C）/w（N）比，较低的土壤w（C）/w（N）比和较高的氮素储

Scenario Analysis on Effects of Long-term Fertilization on Soil Carbon and Nitrogen Codependency

The term of carbon （C） and nitrogen （N） codependency, reflecting the relation of mutual dependence, co-transformation and cooperation, is regarded as active factors for improving soil quality, which differs it from the passive couple mechanism for discussing the soil C and N relationship. There was an interrelation of mutual dependence and interaction between C and N in soil. What quantity and composition of soil C and N could facilitate the codependency of C and N？ How much soil N could be sustained by soil C？ These problems deserve further consideration. The paper analysed the change in soil C and N concentrations, effects of fertilization on the soilw（C）/w（N） ratio, soil capacity of conserving N by C, the relationship of soil C and N codependency and its scenario analysis by data mining the long-term fertilization experiment results to explore the biologic potential of soil C and N, improve soil productivity, environment and balanced cycling of soil C and N. By searching literature database, we obtained about 1782 long-term fertilization data on carbon and nitrogen in China soil from 69 representative articles. Results from analyzing these data sets indicated that the correlation between organic C and total N could be expressed by the functionyC=7.66xN＋1.8162 （r2=0.734＊＊,n=737）. The mean concentrations of total N and organic C were 1.17 g？kg-1 and 10.8 g？kg-1, and ranged from 0.08 g？kg-1 to 3.52 g？kg-1 and from 0.64 g？kg-1 to 32.08 g？kg-1, respectively. Carbon to nitrogen ratio （w（C）/w（N）） concentrated on the range from 7.6 to 10.7, accounting for 80% of the total samples. It was helpful to increasew（C）/w（N） through fertilizing inorganic and organic fertilizer together. Solely fertilizing synthesized fertilizers, especially only one fertilizer, decreasedw（C）/w（N） significantly. Under the scenario of the storage rate of 20 kg N·hm-2·a-1 and the targetw（C）/w（N） of 9, 10 and 11, the soil samples of carbon saturation accounted for 52.7