中文摘要：

通过田间试验,比较了＂小麦/玉米/大豆＂体系中的套作玉米与相同种植规格的单作玉米在不同施氮量下（0,90,180,270kg/hm2,分别记为N0、N90、N180、N270）的产量、生物量、氮积累量、氮肥利用率及土壤硝态氮变化。结果表明：（1）单、套作玉米地上部生物量及籽粒产量均随施氮量的增加先增加后略有降低,与N0处理相比,N90、N180、N270处理玉米产量单作玉米分别高18.9%,31.4%,29.4%,套作玉米分别高40.0%,70.1%,64.1%。（2）N0、N90处理下玉米产量套作比单作分别低18.5%,4.0%,其地上部吸氮量套作比单作低11.6%,6.2%;而N180、N270处理下玉米产量套作比单作分别高5.9%,3.4%,套作玉米吸氮量也略高于单作。（3）随施氮量增加单、套作玉米的氮肥吸收利用率及农学利用率均逐渐降低,套作玉米的氮肥吸收利用率及农学利用率平均分别为39.7%和17.6kg/kg,而单作玉米分别为34.1%和9.9kg/kg,套作比单作分别高16.4%和77.8%。（4）单、套作玉米土壤硝态氮含量均随生育时期推进呈先增高后降低的趋势;玉米种植行（窄行）土壤硝态氮在玉米播种时是套作比N0-N270各处理对应单作分别低19.7%,14.4%,14.1%,20.0%;玉米收获期时,N0处理仍是套作低于单作,其余处理为套作高于单作;玉米宽行各时期土壤硝态氮含量在套作单作间差异较大,这是由于套作玉米的前作小麦施肥、生长及后作大豆生长的影响所致。综上说明,玉米应适量施氮,单套作玉米应有不同的施肥策略以适应各自不同的土壤营养环境。

英文摘要：

Through carrying out field experiments,we compared the yield,biomass,nitrogen accumulation,and nitrogen utilization rate of maize and soil nitrate content under 2planting patterns：＂wheat/maize/soybean＂relay intercropping and maize monocropping,with 4levels of nitrogen application amount（0,90kg/hm2,180kg/hm2 and 270kg/hm2,recorded as N0,N90,N180 and N270）.The results showed that：（1）With the increase of nitrogen application amount,the aboveground biomass and grain yield of maize under both planting patterns firstly increased and then slightly reduced.Compared with N0 treatment,N90,N180,and N270 treatments respectively increased maize yield by 18.9%,31.4% and 29.4% under maize monocropping pattern,while respectively increased maize yield by 40.0%,70.1% and 64.1% under relay intercropping.（2）In N0 and N90treatments,the grain yields of maize under relay intercropping pattern were 18.5% and 4.0% lower than those under monocropping pattern,respectively,and nitrogen uptake amounts of aboveground maize plant under relay intercropping pattern were 11.6% and 6.2% lower than those under monocropping pattern,respectively.In N180 and N270treatments,the grain yields of maize under relay intercropping pattern were 11.6% and 6.2% higher than those under monocropping pattern,respectively,and nitrogen uptake amounts of maize under relay intercropping pattern were slightly higher than those under monocropping pattern.（3）With the increase of nitrogen application amount,the nitrogen absorption rate and agronomy utilization rate of maize gradually decreased under both planting patterns.Thenitrogen absorption rate and agronomy utilization rate of maize were 39.7% and 17.6kg/kg,respectively,under relay intercropping pattern,while they were 34.1% and 9.9kg/kg,respectively,under maize monocropping pattern.Compare with maize monocropping pattern,the relay intercropping pattern increased the nitrogen absorption rate and agronomy utilization rate of maize by 16.4% and 77.8%,respectively.（4）With the growth of maize,