江汉平原不同氮肥运筹模式下豆麦和稻/麦轮作系统小麦产量和经济效益差异

Differences of wheat yield and economic benefits between soybean-wheat and rice-wheat cropping under different nitrogen fertilization patterns in Jianghan Plain, China

研究江汉平原豆麦(大豆/小麦)和稻麦(水稻/小麦)轮作系统中冬小麦生长规律对氮肥运筹模式的响应,可为缩小两种轮作模式下的小麦产量差异提供理论依据。试验设置传统施肥(70%底肥,30%越冬期追肥)和优化施肥(1/3底肥,1/3越冬期追肥,1/3拔节期追肥)2个处理,并以不施氮处理为对照,分析了豆麦和稻麦轮作系统中冬小麦的生长规律、产量及产量构成因素、肥料利用率和施肥效益等。结果表明:施氮和轮作模式均对小麦产量有显著影响,优化施肥产量显著高于传统施肥,两者产量差异在豆麦轮作系统下为920 kg·hm-2,在稻麦轮作系统下为2195 kg·hm-2。相同轮作模式下,传统施肥冬季、春季群体茎蘖数高于优化施肥,而优化施肥在整个生育期干物质总积累量较传统施肥高5%~31%(豆麦)和14%~28%(稻麦)。传统施肥下豆茬小麦产量较高的原因是穗数、成穗率、群体干物质积累量等均高于稻茬小麦;优化施肥下稻茬小麦产量较豆茬小麦增加幅度更大,表明优化氮肥模式可缩小豆麦与稻麦轮作中小麦的产量差异。两种轮作模式中小麦花后粒重分别呈现"慢-快-中"(豆麦)和"中-快-慢"(稻麦)的增加趋势;氮肥农学效率、小麦季纯收益等指标均以稻麦轮作优化施肥处理最高。综上,在江汉平原地区,稻麦轮作优化施肥处理下小麦群体结构合理,干物质积累量较高,产量和施肥效益增加显著,是江汉平原地区兼顾产量与施肥效益的最佳模式。

We analyzed winter wheat yield and growth pattern of soybean-wheat and rice-wheat rotation systems in response to different nitrogen fertilization patterns with the aim to provide theoretical basis for narrowing the wheat yield gap between the two rotations in Jianghan Plain. Field experiments were conducted with three treatments, control without nitrogen, traditional nitrogen management(70% nitrogen as basal and 30% nitrogen as topdressing at overwintering), and improved nitrogen management(one third of N was applied at sowing, wintering and jointing, respectively). The growth pattern, grain yield, yield components, fertilizer use-efficiency and economic benefit under the different nitrogen fertilization patterns were examined. Results showed that grain yield was significantly affected by both nitrogen fertilization pattern and crop rotation. Grain yield under improved nitrogen treatment was significantly higher, with the yield gap being 920 kg·hm-2 in soybean-wheat rotation and 2195 kg·hm-2 in rice-wheat rotation. Traditional nitrogen management showed advantage in establishing winter and spring population. Dry matter accumulation was higher under improved nitrogen treatment than traditional treatment with 5%-31% and 14%-28% increases for soybean-wheat and rice-wheat rotations, respectively. The higher yield in the soybean-wheat rotation was due to greater panicle numbers, higher percentage of tiller ears, and dry matter accumulation. The rice-wheat rotation under improved nitrogen showed a significant increase in grain yield compared with soybean-wheat rotation. This result indicated that yield gap between the two crop rotations could be narrowed through suitable nitrogen management. Grain weight after anthesis showed "slow-fast-medium" in soybean-wheat rotation and "medium-fast-slow" in rice-wheat rotation. Nitrogen use efficiency and net benefit of wheat season were higher in rice-wheat system. Overall, the rice-wheat system showed obvious advantages in population structure, dry matter accumulation, grain yield and benefit under improved nitrogen pattern, which was the optimum pattern for both wheat yield and benefit in Jianghan Plain.