Nitrogen fertilization degrades soil aggregation by increasing ammonium ions and decreasing biological binding agents on a Vertisol after 12 years  

作　　者：Zichun GUO Wei LI Mahbub UL ISLAM Yuekai WANG Zhongbin ZHANG Xinhua PENG 

机构地区：[1]State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Sciences,Nanjing 210008,China [2]Crop Research Institute,Anhui Academy of Agricultural Sciences,Hefei 230031,China [3]University of Chinese Academy of Sciences,Beijing 10049,China [4]Bangladesh Agricultural Research Institute,Gazipur 1701,Bangladesh

出　　处：《Pedosphere》2022年第4期629-636,共8页土壤圈（英文版）

基　　金：supported by the National Natural Science Foundation of China(Nos.41725004,42007007,and 41930753);the Natural Science Foundation of Jiangsu Province,China(No.BK20201104).

摘　　要：Degraded soil aggregation arising from nitrogen(N)fertilization has been reported in many studies;however,the mechanisms have not yet been clarified.Elucidating the impact of N fertilization on soil aggregation would help to improve soil structure and sustain high crop production.The objective of this study was to determine the impact of long-term N fertilization on soil aggregation and its association with binding and dispersing agents.A 12-year(2008–2019)N fertilization field experiment on a Vertisol was performed,covering a wide range of N application rates(0,360,450,540,630,and 720 kg ha-1 year-1)and including straw management(straw return and straw removal)in a wheat(Triticum aestivum L.)-maize(Zea mays L.)cropping system.Soil samples of 0–20 cm depth were collected from 12 field treatments with 3 replications in 2019.Soil aggregate stability(mean weight diameter(MWD))and contents of soil organic carbon(SOC),glomalin-related soil protein(GRSP),microbial biomass carbon(MBC),and mineral N(NH4+and NO3-)were determined.Long-term N fertilization under straw removal conditions reduced soil MWD by 12%–18%at N rates from 0 to 720 kg ha-1 compared to that under straw return(P<0.05).Soil MWD was positively associated with pH(P<0.05)and MBC(P<0.05),but negatively correlated with NH4+(P<0.05)and NO3-(P<0.05).Compared with the straw removal treatment,the straw incorporation treatment significantly improved the contents of aggregating agents(SOC,GRSP,and MBC)(P<0.001),but did not affect that of the dispersing agent(NH4+)(P>0.05);consequently,it improved soil aggregation.Overall,our results indicate that long-term N fertilization may degrade soil aggregation because of the increases in monovalent ions(H+and NH4+)and the decrease in MBC during soil acidification,especially when the applied N dose exceeded 360 kg ha-1 year-1.Our finding can minimize the negative structural impacts on Vertisol.

关 键 词：aggregating agents aggregate stability long-term nitrogen fertilization soil structure straw incorporation 

分 类 号：S143.1[农业科学—肥料学]