| In view of the fact that excessive fertilization can not bring about the increase of crop yield,but also lead to a series of problems such as the increase of production cost and the aggravation of environmental pollution,this paper explored the effect of different optimized fertilization techniques on nitrogen reduction and efficiency increase of maize and wheat,as well as the influence on soil properties,aiming to clarify the effective and feasible technical measures for nitrogen reduction and efficiency increase and soil fertilization improvement in maize and wheat production,so as to provide theoretical basis and technical support for the improvement of grain field productivity and the cultivation of cultivated soil health.The main results are as follows:(1)The results of nitrogen fertilizer reduction technology showed that on the basis of farmers’ traditional nitrogen application(210 kg/hm2),20%～40%nitrogen reduction in the first season of maize and 12.5%～25%nitrogen reduction in the second season of wheat would not have a significant effect on maize/wheat yield and nutrient accumulation.However,the sustainable nitrogen reduction ratio remains to be further explored.(2)Under the condition of equal nitrogen application,the effect of inhibitor on maize/wheat yield was not significant,but the dry matter accumulation before an-thesis was significantly increased by 12.68%.The treatment of nitrogen fertilizer combined with organic fertilizer and inhibitor(N1+1+O)significantly increased the dry matter accumulation of maize before anthesis by 13.47%,and significantly increased the dry matter accumulation of wheat after anthesis by 31.79%.Inhibitor regulation can significantly increase the root length density of two crops by 12.06%～14.89%,and promote crop root growth.Nitrogen fertilizer reduction and combined application of inhibitors could significantly increase the nitrate reductase activity of maize leaves by 13.79%～27.62%during vegetative growth.The application of organic fertilizer had no significant effect on the yield and nutrient utilization efficiency of maize and wheat,but it could effectively improve the root length density and leaf nitrate reductase activity.Compared with single application of chemical fertilizer,inhibitor regulation can effectively increase soil ammonium nitrogen content by 3.25%～30.24%and reduce soil nitrate nitrogen content by 12.56%～18.42%in the early growth stage of maize/wheat.(3)Compared with the single application of chemical fertilizer(N),the soil compactness of single application of organic fertilizer(OM),nitrogen fertilizer combined with organic fertilizer(N+OM),nitrogen fertilizer combined with organic fertilizer and inhibitor(N+UN+OM)decreased by 15.35%,14.28%and 14.69%,respectively.There was no significant change in soil bulk density.The soil water-soluble salt content was significantly reduced by 10.23%～11.35%.The results of soil carbon fractions showed that although there was no significant difference in total organic carbon between the two seasons,the soil readily oxidizable organic carbon(LOC),microbial biomass carbon(MBC),soluble organic carbon(DOC),soil alkaline phosphatase activity,and arylsulfatase activity were increased by 9.74%～13.25%,18.74%～26.48%,13.58%～19.63%,9.39%～12.37%,7.27%～10.13%,respectively.The soil quality comprehensive index SQI of optimized fertilization technology was significantly increased by 9.93%～64.46%.In summary,on the basis of conventional fertilization,nitrogen reduction by 20%～40%in maize season and 12.5%～25%:in wheat season,combined with nitrogen fertilizer synergism and organic fertilizer can optimize crop growth on the basis of ensuring yield,effectively delay the nitrification process of ammonium nitrogen and reduce nitrogen loss.The application of nitrogen and organic fertilizer can effectively improve soil physical,chemical and biological properties and improve soil quality. |
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