Effects Of Nitrogen Synergist On Potato Growth And Soil Mineral Nitrogen

The efficiency of potato nitrogen fertilizer use in China is low.Rational use of nitrogen fertilizer synergist is an important way to improve the efficiency of nitrogen fertilizer use and reduce environmental pollution.In this study,potted controlled randomized block experiment design was used to set up nitrogen application level(experiment 1)and fertilization mode(experiment 2).In experiment 1,the levels of nitrogen application at 30,60,90,120 and 150 kg hm2 were set up,and the nitrogen synergist N-butyl thiophosphoramide(NBPT),dicyandiamide(DCD),2-chloro-6-trichloromethylpyridine(CP)and no nitrogen synergist were added.In experiment 2,total base fertilizer,70% base fertilizer + 30% seedling topdressing(primary topdressing),50% base fertilizer + 30% seedling topdressing + 20% potato topdressing(secondary topdressing).)The three fertilization methods were combined with adding dicyandiamide(DCD),N-butyl thiophosphamide(NBPT)and no nitrogen synergist(control).To study the regularity of soil mineral nitrogen change,to understand the photosynthetic capacity,leaf nitrogen transformation characteristics and growth and development of potatoes,and to explore the rational nitrogen management of potatoes in spring and autumn.The results show that:1.In different levels of nitrogen application,the application of DCD and CP could increase the content of ammonium nitrogen in spring potato soil by 2.7-68.3 mg/kg and the ratio of ammonium to nitrate in soil by 4.40-36.26 times.The content of nitrate nitrogen in soil and leaves was maintained at low levels of 2.14-7.92 mg/kg and 57.5-371.0 mg/kg,which could prolong the efficiency of urea fertilizer and reduce the nitrate content in potato plants.Write.Nitrogen synergists DCD,CP and NBPT significantly increased photosynthetic capacity,dry matter quality and yield of Autumn Potato in late growth stage,but had no significant effect on Spring Potato Yield and dry matter quality.2.In different levels of nitrogen application,with the development of growth period,the effects of nitrogen synergists DCD and CP decreased rapidly at low nitrogen level,and the effect was the best at seedling stage.They increased soil ammonium nitrogen content by 53.25-68.33 mg/kg and soil ammonium-nitrate ratio by 27.6-50.6 times,respectively.The effect of medium nitrogen level increased first and then decreased,and the effect was the best at tuber formation stage,which increased soil ammonium nitrogen content by 29.7-58.6 mg/kg and ammonium content by 29.7-58.6 mg/kg,respectively.The ratio of nitrate increased by 11.8-26.8 times.3.Among the different fertilization methods,topdressing with nitrogen fertilizer and nitrogen synergist could significantly reduce soil urease activity,soil apparent nitrification rate and increase soil ammonium nitrogen and nitrate nitrogen content in the middle and late growth stages of potatoes.In one topdressing treatment,soil ammonium nitrogen content in spring and autumn potatoes treated with DCD and NBPT increased by 124.3%,198.1% and 31.0%,260% respectively,compared with the control.Nitrogen mass fraction increased by 18.4%,31.6% and 33.9%,31.6% respectively.4.Among the different fertilization methods,topdressing nitrogen fertilizer and nitrification urease inhibitor can improve the dry matter quality and yield of potatoes in spring and autumn,but the yield increase effect of spring potatoes is greater than that of autumn potatoes,and the effect of one topdressing treatment is the best.Among them,the yield of Spring Potato increased by 53.3% and 112.0% compared with the control,but Autumn Potato did not reach significant difference.5.Spring potatoes should pay attention to the combination of nitrogen synergists and topdressing fertilizer to reduce the loss of nitrogen in the early stage of soil and ensure the supply of nitrogen in the later stage;autumn potatoes should pay attention to the combination of nitrogen synergists and basic fertilizer,increase the supply of nitrogen in the early stage of soil and reduce the loss of nitrogen in the later stage.