旱地冬小麦产量、氮肥利用率及土壤氮素平衡对降水年型与施氮量的响应

研究不同降水年型施氮量对旱地冬小麦产量、氮素利用及土壤氮素表观平衡的影响,探讨渭北旱塬旱作麦田稳产增效的最佳氮素投入量,为高效施氮提供理论依据。田间定位施氮试验于2017—2020年连续3年在陕西合阳县开展,以长6359为试验材料,设置5个施氮量处理包括0、60、120、180和240 kg hm^-2 (分别以N0、N60、N120、N180和N240表示),研究旱地冬小麦产量、氮肥利用率及土壤氮素平衡对降水年型与施氮量的响应。连续3年定位试验表明:(1)降水年型对冬小麦产量和经济收益影响显著,丰水年较平水年和欠水年分别增产33.6%和113.3%,经济收益提高2～3倍以上。冬小麦氮肥回收利用率和农学效率与产量有相似的变化规律,丰水年氮肥回收利用率和农学效率较平水年和欠水年分别提高4.7个百分点、0.6 kg kg–1 (平水年)和11.9个百分点、2.5 kg kg–1 (欠水年)。(2)无论何种降水年型,冬小麦产量、氮肥回收利用率和农学效率均随施氮量增加呈现先增加后下降的趋势。在丰水年和平水年,均以N180处理下最高,收获期0～100 cm土层土壤硝态氮积累分...

Response of winter wheat yield,nitrogen use efficiency and soil nitrogen balance to rainfall types and nitrogen application rate in dryland

To study the effects of nitrogen application rate on grain yield,nitrogen utilization,and soil nitrogen balance of dryland winter wheat fields under different rainfall types,we explored the optimal nitrogen input levels for stable yield and high efficiency of winter wheat in the Weibei highland of North China,which could provide a theoretical basis for efficient fertilization.Five nitrogen treatments including 0,60,120,180,and 240 kg hm^-2(designated as N0,N60,N120,N180,and N240,respectively)were arranged in Heyang County,Shaanxi Province from 2017 to 2020.The three-year in situ experiment were as follows:(1)Different rainfall types had significant impact on yield and economic profits of winter wheat.Compared with the normal and dry year,the yield of the humid year was increased by 33.6%and 113.3%and economic profits were increased by two to three times or more.Nitrogen fertilizer recycling and agronomic efficiency of winter wheat had similar change patterns with yield,and the nitrogen fertilizer recycling,and agronomic efficiency were increased by 4.7%,0.6 kg kg^-1(normal year),and 11.9%,2.5 kg kg^-1(dry year)in the humid year compared with the normal and dry year.(2)Regardless of the rainfall type,the yield and nitrogen fertilizer recycling and agronomic efficiency of winter wheat increase first and then decrease with the increase of N application.The highest values were found under N180 treatment in both humid and normal years,and the NO₃^--N accumulation in 0-100 cm layer after wheat harvest were 108.9 and 113.6 kg hm^-2,respectively.In dry year,the NO₃^--N accumulation under N120 treatment in 0-100 cm layer after wheat harvest was 100.8 kg hm^-2 reaching the highest value.(3)The threshold of nitrogen input was determined by the best economic benefit and the highest yield,the nitrogen application rates in humid year,dry year,and normal year were 158.9-166.5,121.2-130.0,and 148.1-155.7 kg hm^-2,respectively;The threshold of nitrogen input was determined by the balance of soil nitrogen pool and the maximum nitrogen uptake,the nitrogen application rates in humid year,dry year,and normal year were 166.5-190.3,109.6-147.7,and 153.5-198.9 kg hm^-2,respectively.Considering the high yield and high efficiency of winter wheat and low soil nitrogen loss,we concluded that when the nitrogen application rates in humid year,dry year,and normal year were 158.9-190.3,109.6-147.7,and 148.1-198.9 kg hm^-2,respectively.It was the suitable nitrogen application rate for both high yield and good environmental benefits,which could be benefit for reference in the production of this region.