减氮节水对引黄灌区春小麦耗水特征及水分利用效率的影响

Effects of nitrogen reduction and water saving on water consumption characteristics and water use efficiency of spring wheat in Ningxia Yellow River irrigation area

以‘宁春4号’春小麦为供试材料,于2021-2022年开展田间试验,采用二因素裂区设计,主区为灌溉定额包括常规灌溉(400 mm,WC)、节水20%灌溉(320 mm,W1)和节水40%灌溉(240 mm,W2),副区为施氮水平包括常规施氮(270 kg·hm^(-2),NC)、减施氮肥25%(202.5 kg·hm^(-2),NJ)和不施氮(N0),灌溉方式为微喷灌,研究减氮节水对土壤水分动态分布、春小麦产量及水分利用效率的影响。结果表明:NJW1处理促进了春小麦吸收20~40 cm土层的水分,土壤含水率变化多发生在60 cm以上土层,减少了水分下移。2 a试验中均以NJW1处理的春小麦籽粒产量最高,分别为8092 kg·hm^(-2)和5516 kg·hm^(-2),较常规施氮常规灌溉处理分别提高7.01%和13.36%,并显著提高了春小麦穗粒数和千粒质量。在相同施氮量条件下,灌溉定额处理之间总耗水量存在显著差异,且随灌溉定额增加呈增加趋势,2 a试验中,NJW1处理春小麦全生育期耗水量较相同施氮下常规灌溉处理分别减少14.07%和18.37%。减施氮肥下W1处理2 a的春小麦水分利用效率分别可达1.62 kg·m^(-3)和1.43 kg·m^(-3),较减施氮肥常规灌溉处理分别提高21.80%和31.19%。综上所述,在两种水文年型春小麦生育期间降雨量分别为67.5 mm(干旱年份)和34.5 mm(极端干旱年份),在减氮25%节水20%的水氮管理模式下,春小麦可达到高产和水分利用效率高效的目标,可在宁夏引黄灌区进行推广。

A two-factor split-plot field experiment with three replications was conducted in 2021 and 2022 with Ningchun 4 as the test material.The primary treatments involved different irrigation quotas:conventional irrigation(WC)with 400 mm,W1 with a 20%water saving(320 mm),and W2 with a 40%water saving(240 mm).Secondary treatments included nitrogen application rates:NC(270 kg·hm^(-2)),NJ(a 25%reduction in nitrogen fertilizer,202.5 kg·hm^(-2)),and N0(no nitrogen application).The study aimed to investigate the effects of reduced nitrogen application and water-saving practices on soil water distribution,crop yield,and water use efficiency in spring wheat.The findings are intended to provide a theoretical basis for efficient water use under reduced nitrogen fertilizer in the Ningxia Yellow River irrigation area.The results indicated that reducing nitrogen by 25%and saving 20%of water increased water uptake by spring wheat in the 20~40 cm soil layer.Most changes in soil water content occurred above 60 cm,which limited the downward movement of water.At the same time,the highest yield of spring wheat was achieved with the treatment 25%N reduction and 20%water saving,8092 kg·hm^(-2)and 5516 kg·hm^(-2)in 2021 and 2022,increasing by 7.01%and 13.36%as compared with the conventional irrigation quota and N application.Meanwhile,the number of grains on the spike and the thousand grain quality of spring wheat were significantly raised with the treatment 25%N reduction and 20%water saving.Under the same N application,the total water consumption was significantly different between irrigation quota treatments and tended to increase with the increase of irrigation quota,and the water consumption of spring wheat under 25%N reduction and 20%water saving treatment decreased by 14.07%and 18.37%compared with that of conventional irrigation,respectively in 2021 and 2022.The water use efficiency of spring wheat with 20%water saving under N reduction were up to 1.62 kg·m^(-3) and 1.43 kg·m^(-3),which were 21.80%and 31.19%higher than that of the conventional irrigation treatment.In conclusion,during a dry or extremely dry year with only 67.5 mm or 34.5 mm of rainfall during the spring wheat growth period,a 25%reduction in nitrogen(202.5 kg·hm^(-2))and a 20%reduction in water usage(320 mm)represent an optimal irrigation and nitrogen management strategy.This approach ensures high yield and efficient water use for spring wheat in the Yellow River irrigation area.