【摘要】 目的】探究长期不同施氮量对土壤团聚体碳氮含量及小麦产量的影响,为合理施氮提供理论依据。【方法】基于设置在河南省许昌市张潘镇4个不同施氮水平11年定位试验，施氮量分别为0（N0）、180 kg·hm^-2（N1）、240 kg·hm^-2（N2）及300 kg·hm^-2（N3），分析不同处理土壤碳氮含量、团聚体分布及其碳氮含量的变化，并探寻长期施氮对小麦产量及其构成的调控路径。【结果】随着施氮量增加，各土层土壤团聚体分布呈现大团聚体（>0.25 mm）向微团聚体（0.053—0.25 mm）和粉黏粒组分（<0.053 mm）转化的趋势，显著降低了团聚体平均重量直径（MWD）。土壤碳、氮含量在0—20cm土层随施氮量增加而逐渐上升，20—40 cm土层呈先升高后降低趋势。与N0相比，0—20 cm土层各施氮处理土壤有机碳和全氮含量的平均增幅分别为13.1%—37.2%和19.4%—29.4%;20—40 cm土层的平均增幅分别为15.3%—32.2%和6.1%—29.3%。长期施氮处理显著提高了各粒级团聚体有机碳含量，与N0相比，施氮处理大团聚体有机碳平均含量提高31.6%—62.0%，微团聚体提高8.7%—61.2%，粉黏粒提高14.0%—81.7%。在0—20 cm土层，各粒级团聚体全氮含量亦随施氮量增加而增加，各施氮处理大团聚体、微团聚体和粉黏粒中全氮含量平均增幅分别为32.6%—51.0%、25.7%—35.9%和3.2%—9.7%，且均以N3处理最高。在20—40 cm土层，各粒级团聚体全氮含量随施氮量增加呈先升高后降低趋势，各施氮处理大团聚体、微团聚体和粉黏粒全氮含量平均增幅分别为17.6%—35.2%、11.7%—24.0%和1.1%—12.9%，且均以N1处理最高。研究结果还表明，长期施氮显著增加了小麦成穗数和穗粒数，进而提高了产量。与N0相比，N1、N2和N3处理分别提高小麦产量188.1%、177.3%和173.2%。相关分析与结构方程模型分析表明，小麦产量与土壤碳、氮含量及团聚体中碳、氮含量均呈显著正相关，长期施氮通过改变土壤及团聚体中碳、氮含量进而影响小麦产量。【结论】综上，长期合理施氮提高了土壤及团聚体中碳、氮含量，提升了土壤肥力，促进小麦增产。在本试验条件下以施氮量180 kg·hm^-2时最优。更多还原

【Abstract】 t:【Objective】The influence mechanism of varying nitrogen （N） rates on the carbon （C） and N content of soil aggregate,as well as wheat yield were investigated in this study,so as to provide a scientific basis for the rational application of N fertilizer.【Method】The 11-year experiment was conducted in Zhangpan Town,Xuchang City,Henan Province,with four different N levels,including 0 （N0）,180 kg·hm^-2 （N1）,240 kg·hm^-2 （N2）,and 300 kg·hm^-2 （N3）.The study systematically analyzed changes in soil carbon and nitrogen content,cluster distribution and their carbon and nitrogen content in different soil layers as a result of long-term N application,and investigated the regulatory pathways of long-term N application on wheat yield and its composition.【Result】There was a transformation in the composition of soil aggregates in every soil layer,specifically from larger macroaggregates （>0.25 mm） to microaggregates （0.25-0.053 mm） and silt and clay particles （<0.053 mm）,as well as an increase in N rate.Additionally the application of N resulted in a significant decrease in the mean weight diameter （MWD）.As N application rates increase,the C and N content of the soil increased in the 0-20 cm layer,the C and N content of the soil in the 20-40 cm soil layer showed the trend to increase at first and then decrease.Compared with the N0 treatment,N application increased soil organic carbon （SOC） and soil total nitrogen （STN） content by 13.1%-37.2%and 19.4%-29.4%in the 0-20 cm layer and by 15.3%-32.2%and 6.1%-29.3%in the 20-40cm layer,respectively.The N treatment significantly increased the SOC content of each particle size aggregates compared with N0treatment,with the SOC content of macroaggregates increasing by 31.6%-62.0%,the SOC content of microaggregates increasing by8.7%-61.2%and the SOC content of silt and clay increasing by 14.0%-81.7%.As N application rates increased,the STN content of the soil increased in the 0-20 cm layer.With the STN content of macroaggregates increasing by 32.6%-51.0%,the STN content of microaggregates increased by 25.7%-35.9%and the STN content of silt and clay increased by 3.2%-9.7%,the N3 treatment had the highest STN content of all particle size aggregates.In the 20-40 cm soil layer,the STN content of all particle size aggregates tended to increase at first and then decrease.With the STN content of macroaggregates increasing by 17.6%-35.2%,the STN content of microaggregates increased by 11.7%-24.0%and the STN content of silt and clay increased by 1.1%-12.9%,and the N1 treatment had the highest STN content of all particle size aggregates.The study results indicated that long-term nitrogen application had a significant impact on the spike number and grain number per spike in wheat,resulting in increased yield.Compared with the N0treatment,the application of N1,N2,and N3 treatments resulted in a significant increase in wheat yield,with improvements of188.1%,177.3%,and 173.2%,respectively.The correlation and structural equation modelling analyses revealed a significant and positive correlation between wheat yield and soil carbon and nitrogen content,as well as carbon and nitrogen content in aggregates.Additionally,the long-term application of nitrogen was found to influence wheat yield formation by affecting carbon and nitrogen content in microaggregates.【Conclusion】In summary,the application of nitrogen over a long period of time raised the content of carbon and nitrogen in both soil and aggregates,enhanced soil fertility,ultimately promoting wheat yield.The optimal nitrogen application rate was 180 kg·hm^-2 under the condition of this experiment.更多还原