玉米秸秆还田配施氮肥对豫西旱地小麦土壤酶活性和氮肥利用效率的影响

Effects of maize straw return combined with nitrogen on soil enzyme activity and nitrogen fertilizer use efficiency in western dryland wheat fields of Henan Province

为阐明玉米秸秆还田配施氮肥条件下土壤酶活性、氮肥利用效率及产量的变化规律,本试验选用洛旱22为材料,采用裂区试验设计,主区为玉米秸秆还田处理,分别为秸秆不还田(S_(0))、秸秆全量还田(S_(1)),副区为施氮量处理,分别为0(N_(0))、120(N_(1))、180(N_(2))、240(N_(3))和300 kg·hm^(-2)(N_(4)),测定了小麦各生育期0~20 cm和20~40 cm土层土壤脲酶、蔗糖酶、过氧化氢酶及蛋白酶活性,并分析计算小麦产量、氮肥农学利用率、氮肥表观回收率、氮肥偏生产力和氮素吸收效率。结果表明:1)秸秆还田配施氮肥处理较单施氮肥处理提高了土壤酶活性、氮肥利用效率和小麦产量,小麦产量以秸秆还田配施氮肥240 kg·hm^(-2)处理最高,较无秸秆还田不施氮处理增产36.92%。2)土壤酶活性均随施氮量的增加呈先上升后下降的趋势,除拔节期脲酶和蔗糖酶以施氮量180 kg·hm^(-2)时活性最高,其他生育期土壤酶均以施氮量240 kg·hm^(-2)时活性最高。此外,随着土层深度的增加,土壤酶活性逐渐下降。3)随着施氮量的增加,氮肥农学利用率和氮肥表观回收率先上升后下降,以施氮量180 kg·hm^(-2)最高,氮肥偏生产力和氮素吸收效率则表现为逐渐降低。4)土壤酶活性与小麦产量呈显著正相关,与氮肥农学利用率和氮肥表观回收率呈正相关。各生育期,除脲酶活性在拔节期与氮素吸收效率和氮肥偏生产力呈正相关,其他土壤酶活性与之均呈负相关。在豫西旱作区小麦生产中,秸秆还田配施180~240 kg·hm^(-2)氮肥可减少氮肥过量损失、改善土壤环境、实现氮素资源高效利用。

This experiment studied the effects on soil enzyme activities,nitrogen fertilizer use efficiency and wheat yield of straw return with nitrogen,in the wheat cultivar Luohan 22.A split field trial design was used with two factors,straw and nitrogen fertilizer.The main plot treatments were:Straw fully cleared(S0)and straw return(S1).The split-plot treatments consisted of differing nitrogen fertilizer application rates:0(N_(0)),120(N_(1)),180(N_(2)),240(N_(3))and 300 kg·ha^(−1)(N_(4)).Soil urease,sucrase,catalase and protease activities of 0-20 cm and 20-40 cm horizons were determined and the wheat yield,the nitrogen fertilizer agricultural utilization rate,nitrogen fertilizer apparent recovery rate,nitrogen fertilizer partial productivity and nitrogen absorption efficiency were measured.It was found that:1)Compared with nitrogen fertilization treatment alone,the soil enzyme activities,nitrogen fertilizer use efficiency and wheat yield were increased by straw return.The wheat yield under S_(1)N_(3)was the highest,and was 36.92%greater than S_(0)N_(0).2)Soil enzyme activity showed a trend of initial increase and then decrease with increasing rate of nitrogen application.Urease and sucrase had the highest activities in N2,while all other soil enzymes had the highest activity at N3.The soil enzyme activities gradually decreased with increasing soil depth.3)The agronomic efficiency and apparent recovery of nitrogen fertilizer initially increased and then decreased with successive increases in nitrogen application rate,with the highest values observed in N2,while the partial nitrogen productivity and nitrogen absorption efficiency decreased gradually with increasing nitrogen application rate.4)The soil enzyme activities were positively correlated with the wheat yield and the apparent recovery of nitrogen fertilizer.In each reproductive period,urease activity was positively correlated with nitrogen absorption efficiency and nitrogen fertilizer partial productivity during the jointing period,while activities of all other soil enzymes were negatively correlated.Straw return combined with 180-240 kg·ha^(−1)nitrogen fertilizer was shown to reduce excess nitrogen loss,improve the soil environment and result in efficient utilization of nitrogen resources in rainfed wheat fields of western Henan Province.