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| Responses of Urea Transformation Dynamics and Nitrous Oxide to Three Urease Inhibitors in Calcareous Soil |
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| KeyWord:calcareous soil; N2O concentration; Unisense N2O microsensor; urease inhibitor; urea nitrogen |
| Author Name | Affiliation | | LI Jun | Xinjiang Production and Construction Group Oasis Eco-agriculture Key Laboratory, Department of Resources and Environmental Science, Agronomy College, Shihezi University, Shihezi 832000, China | | LIU Tao | Xinjiang Production and Construction Group Oasis Eco-agriculture Key Laboratory, Department of Resources and Environmental Science, Agronomy College, Shihezi University, Shihezi 832000, China | | CHU Gui-xin | Xinjiang Production and Construction Group Oasis Eco-agriculture Key Laboratory, Department of Resources and Environmental Science, Agronomy College, Shihezi University, Shihezi 832000, China |
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| Abstract: |
| Understanding the effects of urease inhibitors on urea hydrolysis and soil nitrous oxide（N2O） emissions may help improve fertilizer N utilization efficiency and mitigate soil N2O production in calcareous soil. In the present research, the effects of three different urease inhibitors, n-（n-butyl）thiophosphoric triamide（NBPT）, ammonium thoisulfate（ATS） and gossypol acetate（GA）, on urea hydrolysis dynamics and soil ammonium and nitrate transformations were examined in a soil culture experiment under greenhouse conditions. Soil N2O concentrations were also determined in situ using Unisense N2O micro-sensor. Fifty percent of applied urea was hydrolyzed within one day, and almost all applied urea hydrolyzed within three days after amendment. During 14 day period, urea hydrolysis was obviously inhibited by NBPT, ATS and GA. In the NBPT amendment, the inhibition rate was greatest, with 33.6%, and urea residue in soil was the highest. Soil NH+4-N content was statistically lower in NBPT supply than in other treatments（P<0.05）. Soil N2O concentrations maintained very low during of the first 4 day, then increased sharply，until the peak occurring on the 6th day, and then decreased obviously during 6th~9th day. Soil N2O concentrations were in order：urea＞urea+GA＞urea+ATS≥urea+NBPT. Furthermore, N2O concentrations were higher during the day than at night, with diurnal variation ranging from 0.25~3.15 μmol·L-1. The path coefficients between N2O concentration and different forms of soil mineral N were：NO-3-N（0.641）＞NH+4-N（0.356）＞Urea-N（0.255）. There was a significant positive relationship between soil NO-3-N and N2O contents, indicating that soil nitrate would be one of key factors influencing soil N2O emission. In conclusion, applying NBPT, ATS and GA inhibits urea hydrolysis and decreases soil N2O generation in calcareous soil, with NBPT as a promising urease inhibitor. |
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