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Effects of maize straw and straw biochar on soil fertility and the nitrogen mineralization process
Received:January 30, 2018  
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KeyWord:straw;straw biochar;black soil;organic matter;nitrogen mineralization
Author NameAffiliationE-mail
ZHU Xing-juan College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China  
LI Gui-hua National Engineering Laboratory for Improving Quality of Arable Land, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agriculture Science, Beijing 100081, China  
TU Shu-xin College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China  
YANG Jun-cheng National Engineering Laboratory for Improving Quality of Arable Land, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agriculture Science, Beijing 100081, China  
GUO Kang-li National Engineering Laboratory for Improving Quality of Arable Land, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agriculture Science, Beijing 100081, China  
JI Zheng-yu National Engineering Laboratory for Improving Quality of Arable Land, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agriculture Science, Beijing 100081, China  
LIU Xiao National Engineering Laboratory for Improving Quality of Arable Land, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agriculture Science, Beijing 100081, China  
ZHANG Jian-feng National Engineering Laboratory for Improving Quality of Arable Land, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agriculture Science, Beijing 100081, China zhangjianfeng@caas.cn 
JIANG Hui-min National Engineering Laboratory for Improving Quality of Arable Land, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agriculture Science, Beijing 100081, China jianghuimin@caas.cn 
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Abstract:
      The effects of maize straw and straw biochar incorporation on soil fertility and nitrogen mineralization in a typical black soil of Northeast China were studied to provide a theoretical basis for improvement of soil fertility and efficient utilization of nitrogen nutrients. A4-year field experiment, 15N tracing experiment, and flooding incubation experiment were carried out to study nitrogen mineralization characteristics under five treatments:chemical fertilizer (N1) as control, N1+50% maize straw (N2), N1+100% maize straw (N3), N1+50% maize straw biochar (N4), and N1+100% maize straw biochar (N5). Soil samples (0~20 cm) were collected and analyzed after maize harvesting.Incorporation of all the organic material combinations (straw and straw biochar) increased the soil organic matter, total nitrogen, available phosphorus, available potassium, and alkali nitrogen contents compared to the N1 treatment. Microbial biomass C and N also were enhanced under organic material incorporation conditions, with N3 treatment significantly increasing the microbial biomass carbon and nitrogen contents by 15.1% and 23.1%, respectively (P<0.05). Both the net soil nitrogen mineralization amount and rate were improved with straw or straw biochar incorporation. The Integrated Fertility Index (IFI) values of the different treatment methods were ordered from high to low as N3 > N5 > N4=N2 > N1, with straw and straw biochar return significantly improving the soil fertility. In addition, the N2 and N3 treatments significantly raised the mineralization amount by 23.4% and 53.0% respectively, and the mineralization rate by 22.9% and 35.8% (P<0.05). The nitrogen mineralization amount of exogenous 15N fertilizer also increased significantly under the N2, N3, N4, and N5 treatments by 66.5%, 213.3%, 39.4%, and 92.0% respectively, and the nitrogen mineralization rate increased by 50.0%, 279.0%, 36.3%, and 40.0% (P<0.05). The soil nitrogen mineralization index had significant positive correlations with soil organic matter, total nitrogen, alkali nitrogen, and microbial biomass. Maize straw and straw biochar incorporation significantly improved soil nutrient conditions and the microbial biomass in the black soil. The nitrogen mineralization rate also was enhanced under the same treatments. Moreover, maize straw or straw biochar incorporation could synergistically improve the contribution of exogenous 15N fertilizer to total mineralized nitrogen, especially with 100% straw return.