| In order to reduce soil non-point source pollution and improve wheat yield and quality through rational fertilization, the effects of mixed application of organic and chemical fertilizers on soil nitrogen conversion and grain quality of winter wheat and the appropriate mixed application ratio of organic fertilizer were studied. Six treatments were set up in Yuanyang county, Henan: no fertilization (CK), no nitrogen fertilization (-N), conventional chemical fertilization (+N), 25% nitrogen substituted with organic fertilizer (T25), 50% nitrogen substituted with organic fertilizer (T50) and 100% nitrogen substituted with organic fertilizer (T100). After three years of treatment, the concentrations of nitrogen contents, nitroconvertase activity, the yield and yield components of winter wheat and the contents of ammonium, nitrate, protein, free amino acid, glutamine and asparagine in wheat grain were measured in 2020 and 2021. Our results found compared to the +N treatment, T25, T50 and T100 treatments decreased soil ammonium contents, and T50 treatment significantly increased nitrate content in 0-20 cm and 20-40 cm soil layers. Compared to CK or NPK treatments, organic fertilization could increase soil organic nitrogen content in topsoil. T25, T50 and T100 treatments could both increase the activity of soil urease, protease, nitrate reductase and nitrite reductase. The wheat yield and the contents of ammonium, protein, glutamine and asparagine in wheat grain were highest in the T50 treatment. Conclusively, in the cultivation of wheat of fluvo-aquic soil in northern Henan Province, 50% nitrogen reduction by chemical fertilizer combined with 50% organic fertilizer can promote soil nitrogen conversion and improve wheat yield and quality effectively. |
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