麦季氮肥运筹对冬小麦–夏玉米种植体系物质生产及氮肥利用的影响

2009-2011年在山东临沂冬小麦-夏玉米生产田，探讨了麦季施氮水平和施氮时期对两季作物干物质积累与分配、籽粒产量、氮肥农学利用率和氮肥偏生产力的影响。施氮量设4个处理，分别是0 (N0)、168.75 (N1)、225 (N2)和281.25 kg hm^-2 (N3)；氮肥追施时期设2个处理，分别为拔节期(S1)和拔节期+开花期(S2)。在S1条件下，冬小麦和夏玉米的籽粒干物质积累量及夏玉米和周年生物产量均表现为N3>N2>N1，冬小麦和夏玉米的籽粒产量N2和N3处理间无显著差异；氮肥农学利用率和氮肥偏生产力在麦季随施氮量增加显著降低，而在玉米季则逐渐升高，但玉米季氮肥偏生产力N3与N2处理间无显著差异。S2条件下麦季施氮量由N2处理增加25% (N3)，冬小麦和夏玉米籽粒干物质积累量、生物产量和籽粒产量无显著变化，氮肥农学利用率和氮肥偏生产力在麦季显著降低、在玉米季无显著变化。与S1相比，S2有利于提高N1和N2条件下冬小麦籽粒与营养器官的干物质积累量、生物产量、籽粒产量和氮肥农学利用率及氮肥偏生产力，但对N3条件下的这些指标无显著影响；而在玉米季，3个施氮量水平下夏玉米的各项指标均显著升高。综合周年生物产量、籽粒产量和氮肥农学利用率及氮肥偏生产力结果，麦季总施氮量225 kg hm^-2及拔节期+开花期追氮是本试验条件和种植模式下的最佳麦季氮肥运筹模式。

Effects of Nitrogen Management in Wheat Season on Matter Production and Nitrogen Use Efficiency in Winter Wheat–Summer Maize Rotation System

Management of nitrogen (N) fertilizer is a constant topic in crop cultivation aiming at high-yield and good-quality production as well as environmental protection. In winter wheat–summer maize rotation system, N fertilizer input in the wheat season has a subsequent influence on the maize season. In this study, we carried out a two-year field experiment in Linyi of Shandong Province, China from 2009 to 2011 with treatments of four N application rates and two topdressing schemes. In the wheat season, the N application rates were 0 (N0), 168.75 (N1), 225 (N2), and 281.25 kg ha^-1 (N3), and the topdressing N was given at jointing stage (S1) and jointing + anthesis stage (S2). In the maize season, N fertilizer of 60 kg ha^-1 was applied before sowing and 90 kg ha^-1at 12-leaf stagein all treatments except for N0 (no N applied in the maize season as well). The dry matter accumulation and distribution, grain yield, nitrogen agronomic use efficiency (NAUE), and nitrogen partial factor productivity (NPFP) were investigated in both wheat and maize seasons. Under the S1 condition, dry matter accumulations in grains of wheat and maize and the biomasses of maize as well as the biomass of both crops heightened with N rate increased, but the grain yields of wheat and maize had no significant differences between N2 and N3 treatments. As the N rate increased, NAUE and NPFP decreased in winter wheat but increased gradually in summer maize; however, the difference in NPFP between N2 and N3 was not significant. Under the S2 condition, the dry matter accumulations in grain, biomasses, and grain yields of wheat and maize had no significant increases in N3 treatment compared to N2 treatment, although the N application amount was promoted by 25% in N3 treatment. The NAUE and NPFP of wheat decreased significantly due to the more distribution of dry matter in vegetative organs of wheat in N3 treatment than in N2 treatment; whereas, the NAUE and NPFP of maize had no significant changes. In the wheat season, compared to S1, S2 was favorable to increase dry matter accumulationsin grain and vegetative organs, biomass, grain yield, NAUE, and NPFP of winter wheat in treatments N1 and N2, but had no significant effects in treatment N3; in the maize season, S2 showed positive effects on these indices of summer maize in treatments N1, N2, and N3. With the comprehensive consideration of total biomass and grain yield of wheat and maize, NAUE, and NPFP, total N fertilizer of 225 kg ha^-1 in wheat season associated with topdressing at jointing and anthesis stages of wheatare recommended as the optimal management mode in winter wheat–summer maize rotation system under similar conditions to this experiment.