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Effects of irrigation types and biochar amendment on soil nitrifying and denitrifying functional microorganisms
Received:February 08, 2023  
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KeyWord:irrigation method;biochar;nitrification;denitrification;microorganisms
Author NameAffiliationE-mail
LIU Jieyun Key Laboratory of Water-Saving Irrigation Engineering, Ministry of Agriculture and Rural Affairs, Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences, Xinxiang 453002, China
School of Environment and Surveying Engineering, Suzhou University, Suzhou 234100, China 
 
QIU Husen School of Environment and Surveying Engineering, Suzhou University, Suzhou 234100, China  
ZHANG Wenzheng Key Laboratory of Water-Saving Irrigation Engineering, Ministry of Agriculture and Rural Affairs, Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences, Xinxiang 453002, China zhangntggs@163.com 
HU Zhuangzhuang Suzhou Academy of Agricultural Sciences, Suzhou 234100, China  
LÜ Mouchao Key Laboratory of Water-Saving Irrigation Engineering, Ministry of Agriculture and Rural Affairs, Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences, Xinxiang 453002, China  
WANG Yu School of Environment and Surveying Engineering, Suzhou University, Suzhou 234100, China  
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Abstract:
      Presently, it is unclear how biochar regulates the microbial processes of nitrification and denitrification under different irrigation types. Therefore, a field experiment was conducted under four irrigation types(normal flooding, drip, sprinkler and micro-sprinkler irrigations, represented)with three biochar treatments:no biochar treatment(CK), 10 t·hm-2 biochar(LB), and 20 t·hm-2 biochar(HB). Real time PCR technology was adopted to analyze the abundances of nitrification and denitrification functional genes in the joint phase of winter wheat in the North China Plain. Compared to flooding irrigation, the drip, sprinkler and micro-sprinkler irrigation methods significantly reduced soil NH4+-N contents by 49.30%-68.25%, 30.22%-57.19% and 43.63%-56.83%(P<0.05), but increased soil NO3--N contents by 5.14%-62.39%, 0-173.50% and 0-87.90%, respectively. Owing to the low amount of irrigation water compared to flooding irrigation, the drip, sprinkler and micro-sprinkler irrigation methods can create an environment fit for nitrification but unfit for denitrification. This, therefore increased the abundance of AOA-amoA and AOB-amoA genes, in the following order:micro-sprinkler irrigation>sprinkler irrigation>drip irrigation>flooding irrigation. Meanwhile, in all irrigation types, biochar amendment increased the abundance of AOA-amoA and AOB-amoA genes because of the pore structure and adsorption of biochar. Compared with flooding irrigation, the drip, sprinkler and micro-sprinkler irrigation methods decreased the abundances of nosZ genes in the soil. Whereas, in all irrigation types, biochar amendment(particularly the HB treatment) increased the abundance of nosZ genes, and thus may reduce the risk of N2O loss via soil denitrification. Overall, the interaction of saving water irrigation types and biochar amendment can promote soil nitrification, and affect soil denitrification by regulating the activities of denitrifying microorganisms. Biochar addition with 20 t·hm-2 can promote nitrogen adsorption by wheat under micro-sprinkler irrigation.