长期施肥棕壤团聚体分布及其碳氮含量变化

【目的】探究玉米-玉米-大豆轮作体系不同施肥处理对土壤团聚体分布及其有机碳、全氮的影响，以期深入了解施肥对土壤培肥、改善土壤结构的机制。【方法】选取不施肥（CK），化肥（NPK），低量有机肥（M1），低量有机肥与化肥配施（M1NPK），高量有机肥（M2），高量有机肥与化肥配施（M2NPK）6个处理。采集棕壤37年长期定位试验微区不同施肥处理的0-20 cm和20-40 cm土样，分析其水稳性团聚体（ 1 mm、1~0.5 mm、0.5~0.25 mm、0.25~0.053 mm及 0.053 mm）分布及其有机碳、全氮分配特征。【结果】棕壤长期施肥对团聚体分布及其碳氮的影响0-20 cm大于20-40 cm，随土层深度的增加，有机碳（SOC）、全氮（TN）含量减少。各处理团聚体及碳、氮在团聚体中的分配主要在黏粉粒中（40%以上）。与CK相比，NPK处理显著提高了黏粉粒的含量，降低大团聚体与微团聚体含量，显著增加黏粉粒储碳比例；M1、M2处理显著增加 1 mm团聚体数量及其SOC含量，显著增加 0.25 mm各粒级团聚体的储碳比例，且M2处理显著高于M1处理；M1NPK、M2NPK处理也显著增加 1 mm团聚体数量及其SOC含量，M1NPK与M2NPK处理在NPK处理的基础上依次增加0.5~0.25 mm（M1NPK）、1~0.5 mm及 1 mm团聚体的储碳比例，M2NPK处理 0.25 mm团聚体储碳比例最高，土壤团聚体全氮的变化趋势与有机碳类似。【结论】棕壤连续有机无机配合施用可显著增加土壤大团聚体数量、SOC、TN含量及其储碳、氮比例，是提高土壤质量、改善土壤结构的有效施肥措施。

Effect of long-term fertilization on distribution of aggregates and organic carbon and total nitrogen contents in a brown soil

Objectives] The purpose of this study was to investigate effects of different fertilization treatments on soil aggregate distribution,organic carbon and total nitrogen in maize-maize-soybean rotation system,and to gain insight into the mechanism of soil fertility improvement and soil structure.Methods] The treatments were as follows:the control (CK),chemical fertilizer (NPK),low-level organic manure (M1),low-level organic fertilizer and chemical fertilizer (M1NPK),high-level organic manure (M2),and high-level organic fertilizer and chemical fertilizer (M2NPK).The soil samples at 0-20 cm and 20-40 cm soil layers were analyzed to understand the characteristics for their water-stable aggregates (＞ 1 mm,1-0.5 mm,0.5-0.25 mm,0.25-0.053 mm and ＜ 0.053 mm),the contents of SOC and TN and partitioning proportions of SOC and TN.Results] The effects of the long-term fertilization on aggregates distribution,carbon and nitrogen in brown soil at the 0-20 cm layer were greater than those at the 20-40 cm layer,and the contents of soil organic carbon (SOC) and total nitrogen (TN) decreased with soil depth increasing.The distribution of aggregates,and carbon and nitrogen in agglomerates were mainly in the clay particles (above 40％).Compared with CK,NPK significantly increased the content of clay particles,decreased the contents of macro-aggregates and microaggregates significantly.M1 and M2 significantly increased the contents of ＞ 1 mm aggregates and SOC,and carbon storage in ＞ 0.25 mm aggregates.Compared with NPK,the carbon storage ratios of M1NPK and M2NPK were increased in the order of 0.5-0.25 mm (M1NPK),1-0.5 mm and ＞ 1 mm aggregates.The proportion of carbon storage of ＞ 0.25 mm aggregates in the M2NPK was the highest,and that of total nitrogen was similar to that of organic carbon.Conclusions] Continuous organic and inorganic combinations of brown soil can significantly increase the amount of large aggregates,SOC,TN content and its carbon and nitrogen ratio,it is an effective fertilization measure to improve soil quality and soil structure.