摘要：

采用大田试验,研究绿肥油菜还田时期对不同施氮量下春玉米产量及对土壤养分的影响规律,以期为华北平原春玉米减氮增效提供理论依据。采用裂区设计,主区绿肥油菜还田时期分别为无绿肥油菜冬闲田(G0)、始花期(G1)、盛花期(G2)和荚果期(G3),裂区施氮量分别为0 (N0),135(N135),270(N270),405(N405),540 kg/hm²(N540)。收获期五点取样法取土测定土壤养分含量,玉米考种测产。与G0相比,G2处理因春玉米穗粒数均值显著增加5.59%而增产5.89%,G1处理2020年增产6.37%,其中穗粒数增幅8.37%,但G1和G2百粒质量与G0无显著差异;G3处理2020年因穗粒数与百粒质量均值降低2.62%,6.40%,导致减产8.43%;春玉米产量随施氮量增加显著增加;G1、G2和G3处理下,春玉米产量在施氮量为N405、N270和N405时达最高,分别为10 961.21,11 253.34和10 331.12 kg/hm²。线性加平台模型分析可知,G1和G2处理可以保证产量稳定在10 000 kg/hm²以上,实现氮肥减施7.89%~41.45%,2020年G3处理减氮10.53%,产量降低6.27%。与G0相比,G1和G2处理显著提高了土壤有机质、碱解氮含量,增幅分别为8.28%和4.12%,11.17%和12.77%。G1、G2和G3处理土壤全氮含量2019年显著增加6.01%,5.86%,8.00%;G1、G2和G3处理土壤全磷和有效磷含量比G0处理显著降低;处理间全钾含量无差异,但G1和G2处理增加了土壤速效钾含量,2020年G3处理含量比G0降低3.41% (P<0.05)。各土壤养分含量随施氮量呈先增加后降低的趋势,在N270达峰值。综上所述,绿肥油菜于始花期至盛花期还田,可以提高土壤有机质、全氮、碱解氮和速效钾含量,产量稳定在10 000 kg/hm²以上,氮肥减施7.89%~41.45%,实现华北平原春玉米生产稳产减氮增效的目的。

关键词: 绿肥油菜, 还田时期, 施氮量, 春玉米, 产量, 土壤养分

Abstract:

Field experiments were used to study the effects of green manure rape returning stages and different nitrogen application rates on yield of spring maize and soil nutrients,in order to provide a theoretical basis for higher using efficiency on less application of nitrogen on spring maize in Northern China Plains. The experiment adopted a split plot design. The stages of returning in the main plots were winter fallow field without returning (G0),initial flowering (G1),full blooming (G2),and pod (G3). The nitrogen application rates of split plots were as follows: 0(N0),135(N135),270(N270),405(N405) and 540 kg/ha (N540).During the maize harvest stage,the five-point sampling method was used to measure soil samples to determine the soil nutrients' contents of each plot,and the maize yields with constituent factors.The results showed that compared with G0 treatment,G2 treatment significantly increased the yield by 5.89%,while the G1 treatment significantly increased the yield by 6.37% in 2020,of which the increases of grain number per ear were 5.59% and 8.37%,respectively,but there were no significant effect on hundred-grain weight;the yield of G3 treatment reduced 8.43% due to decreases of the average 2.62% of grain number per ear and 6.40% of the average hundred-grain weight in 2020. The yield increased significantly with the increase of nitrogen application rates. Under the G1,G2 and G3 treatments, the yields of spring maize reached the hightest when nitrogen application rates were N405,N270 and N405 which were 10 961.21,11 253.34 and 10 331.12 kg/ha, respectively.The yields were higher than others with nitrogen application rates of N405 and N270 for 10 961.21,11 253.35 kg/a,respectively. Model analysis showed that the G1 and G2 treatments could ensure the yield was stable above 10 000 kg/ha,while the nitrogen fertilizer application could be reduced by 7.89%—41.45%. In 2020,the G3 treatment could reduce the nitrogen by 10.53% and the yield by 6.27%. Compared with G0 treatment,G1 and G2 treatments significantly increased the average of soil organic matter and alkaline nitrogen content by 8.28%,4.12%,11.17%,and 12.77%,respectively. Soil total nitrogen contents in G1,G2 and G3 treatments increased significantly by 6.01%,5.86% and 8.00% in 2019. Rape returning significantly decreased the soil total phosphorus and available phosphorus contents. There were no significant differences of total potassium content among treatments,while soil available potassium contents of G1 and G2 treatments were higher than G0 treatment,and G3 treatment significantly decreased for 3.41% than G0 treatment in 2020. Each soil nutrients' contents increased firstly and then decreased with the increase nitrogen application rates,the value with N270 was the highest. In summary,returning green manure rape to the field from the initial flowering to the full flowering period can increase the soil organic matter,total nitrogen,alkali-hydrolyzable nitrogen and available potassium content. With the nitrogen fertilizer application reduced by 7.89%—41.45%,the yield can also stable above 10 000 kg/ha,which achieve the goal of stabilizing the production of spring maize and reducing nitrogen and increasing efficiency in the North China Plain.

Key words: Green manure, Returning stages, Nitrogen fertilizer application, Spring maize, Yield, Soil nutrient