摘要
团聚体的物理保护是土壤有机碳稳定的重要机制之一,团聚体的形成也必须依赖土壤中的有机碳。通过31年的长期定位试验,研究不同养分管理措施对土壤有机碳及团聚体稳定性的影响,探明土壤各粒级团聚体结合碳的分配状况,探讨土壤团聚体对有机碳的物理保护机制,为西北干旱区农田土壤碳优化管理提供依据。采集6个不同施肥措施的长期试验处理的土样,采用湿筛法对土壤团聚体组分和团聚体结合有机碳进行分离并测定,对土壤总有机碳、团聚体分布状况、团聚体结合有机碳等进行分析,并对土壤团聚体稳定和大团聚的周转进行评价。结果显示,长期施用有机肥的土壤有机碳含量达39.7 g·kg^(-1),比不施肥和秸秆还田分别提高了1.8、1.4倍。有机肥和秸秆还田均可提高土壤有机碳,而单独施化肥或撂荒土壤有机碳仅能维持平衡。除此之外,施用有机肥或秸秆还田,土壤大团聚体分别提高了246%和147%,显著提高了土壤团聚化程度,大团聚体的周转速率分别是不施肥的33%和53%,速率显著减缓(P<0.05),而且还可进一步提高土壤大团聚体,团聚体结合的有机碳向较为稳定的细颗粒态有机碳转化,更有利于有机碳的固定。单独施化肥或撂荒土壤有机碳维持平衡,土壤大团聚体密度和团聚体稳定性均比不施肥有显著提高,大团聚体的周转速率显著减缓。土壤有机碳含量较低时,粉粘粒有机碳含量占主要优势,而当土壤富含有机碳时,细颗粒有机碳含量占主要优势。综上所述,施用有机肥不但可以弥补因耕作的破坏导致的大团聚体下降,还可促进土壤大团聚体的形成,增强土壤团聚体稳定性,新增的有机碳首先与大团聚体结合,然后主要以细颗粒态有机碳固定,效果好于秸秆还田。长期单独施用化肥难以提高土壤有机碳、微团聚体包裹的有机碳和大团聚体中的细颗粒有机碳相对稳定,通过撂荒可减少对土壤的物理破坏,促进大团聚体的积累。
Physical protection of aggregates is one of the important mechanisms of soil organic carbon(SOC)stabilization,and the formation of aggregates also depends on soil organic carbon.Through 31 years of long-term field experiments,the effects of different nutrient management measures on SOC and aggregate stability were studied,the distribution of bound carbon in soil aggregates was ascertained,and the physical protection mechanism of soil aggregates on SOC was explored,which could provide a basis for the optimal management of farmland SOC in the arid region of Northwest China.Soil samples from a long-term experiment with six different fertilization measures were collected,soil aggregate components and aggregate bound organic carbon were separated and determined by wet sieving method,soil total organic carbon,aggregate distribution and aggregate combined organic carbon were analyzed,and the stability of soil aggregates and the turnover of large agglomerations were evaluated.Results showed that the SOC content of manure amendment treatment could up to 39.7 g·kg^(-1),which was 1.8 and 1.4 times higher than those of no-fertilization and straw-returned treatments,respectively.The manure amendment treatment and straw-returned treatment could significantly increase SOC,while fertilization alone or abandoned soil could only maintain the balance of soil organic carbon.In addition,the manure amendment and straw-returned treatments increased the soil macroaggregation by 246%and 147%,respectively.Moreover,the turnover of the macroaggregation of manure amendment and strawreturned treatments were 33%and 53%of no-fertilization,which were significantly slower(P<0.05)than that of no-fertilization treatment.At the same time,the organic carbon bound by the agglomerate was transformed into a relatively stable fine-particle organic carbon,which was more conducive to the fixation of the organic carbon.Applying chemical fertilizer alone or abandoned soil organic carbon could maintain the input and output balance of SOC,the proportion of soil large aggregates and the stability of aggregates were significantly improved compared with no fertilizer,and the turnover rate of large aggregates was significantly slowed down.When the SOC content was low,the organic carbon content of silty clay particles dominated,and when the soil was rich in organic carbon,the fine particle organic carbon content dominated.All in all,the results showed that the application of organic fertilizer could not only make up for the decline of macroaggregates caused by tillage,but also promote the formation of soil aggregates,and the stability of soil aggregates could also be enhanced.The new SOC was first combined with macroaggregates,then fine particulate organic carbon was mainly used for fixation,which was better than straw returning.Long-term application of chemical fertilizer alone was difficult to improve SOC;the SOC encapsulated in microaggregates and fine particles in macroaggregates are relatively stable.Abandoning wasteland can reduce the physical damage to the soil and promote the accumulation of large aggregates.
作者
王西和
杨金钰
王彦平
麦尔耶姆·亚森
黄建
刘骅
WANG Xi-he;YANG Jin-yu;WANG Yan-ping;YASEN Maieryemu;HUANG Jian;LIU Hua(Research Institute of Soil,Fertilizer and Agricultural Water Conservation,Xinjiang Academy of Agricultural Sciences/National Gray Desert Soil Fertility and Fertilizer Effect Monitoring Station/Scientific Observation and Experimental Station of Cultivated Land Conservation and Agricultural Environment in Northern Xinjiang of Ministry of Agriculture and Rural Affairs,Urumqi Xinjiang 830091)
出处
《中国土壤与肥料》
CAS
CSCD
北大核心
2021年第6期1-8,共8页
Soil and Fertilizer Sciences in China
基金
新疆维吾尔自治区自然科学基金(2017D01B26)。
关键词
长期施肥
有机碳
团聚体
团聚体结合碳
团聚体稳定性
大团聚体周转
long-term fertilization
organic carbon
aggregate
aggregate bound carbon
aggregate stability
macroaggregate turnover
