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Gansu Agricultural University (2020)

Long-term Inorganic N Impact on Nitrogen Uptake and Translocation of Spring Wheat and Soil Microorganisms in the Semi-arid Loess Plateau

许爱霞

Titre : Long-term Inorganic N Impact on Nitrogen Uptake and Translocation of Spring Wheat and Soil Microorganisms in the Semi-arid Loess Plateau

Auteur : 许爱霞

Grade : Doctoral Dissertation 2020

Université : Gansu Agricultural University

Résumé partiel
In order to explore the effects and mechanisms of long-term application of inorganic nitrogen fertilizers on nitrogen uptake,translocation and nitrogen utilization efficiency of wheat in the semi-arid region of the Loess Plateau,this study relied on the long-term nitrogen(N)fertilizer experoment started in 2003 to study the effect of urea application on spring wheat yield,nitrogen uptake,translocation,and resorption,soil nitrogen residues,and main soil microorganisms.Treatments included a non-N-fertilized control and annual application of52.5,105.0,157.5,and 210.0 kg N ha-1in the first two years(2003 and 2004).In the third year(2005),the four main plots with N fertilizer application were split.In one subplot,N fertilization was continued as mentioned previously,while in the other subplot,N fertilization was stopped and defined as its corresponding sub-treatments N52.5c,N105c,N157.5c,N210c.The main results were as follows :(1)Application of inorganic nitrogen fertilizer significantly increased the biological yield and grain yield of spring wheat in the semi-arid area of the Loess Plateau.Higher nitrogen fertilizer application rate ensured higher dry matter accumulation and grain yield,but it is not that the higher the N application rate,the better.When the application rate of inorganic N was about 105 kg N hm-2,the grain yield(3062.7 kg hm-2)and nitrogen fertilizer use efficiency(16.40%)of spring wheat were both higher,continues increase in the amount of N fertilizer did not significantly increase grain yield.Compared with non-N-fertilized control,the grain yield of 105 kg N hm-2 treatment increased by 46.90%,and nitrogen absorption increased by 90.54%.(2)With the increase of inorganic nitrogen application rates,the NO3-N content of the0-200 cm soil layer increased significantly,and the soil p H value dropped from 8.99 to 8.70.Compared with sowing,the soil NO3-N content of high nitrogen treatments(N157.5 and N210)showed a significant excess at harvest,with a growth rate of 6.94–76.23%,and mainly occurred at 10–110 cm and 170–200 cm soil layer.Wheat grain yield in the third year(2005)was significantly,greater(22.57–59.53%)than the unfertilized treatment after the N application was stopped.There was a positive relationship of soil NO3-N in the 0–50cm and 50–110 cm soil layers at sowing with grain N content and yield.

Mots clés : N uptake ;N resorption ;Nitrogen use efficiency ;Bacteria;AOA ;AOB;

Présentation (CNKI)

Page publiée le 21 octobre 2021