不同秸秆还田量和氮肥配施对玉米田土壤CO_(2)排放的影响

Effects of different amounts of straw return and nitrogen fertilizer application on soil CO_(2) emission from maize fields

探讨不同秸秆还田量和氮肥量配施对辽西北半干旱区玉米田土壤CO_(2)排放的影响,可为固碳减排和黑土地保护计划的实施提供理论支撑。本试验主区设置3个秸秆还田水平,分别为3000(S_(1))、6000(S_(2))和9000 kg·hm^(-2)(S_(3),秸秆全量还田);副区设置3个氮肥施用水平,分别为105(N_(1))、210(N_(2),常规施氮量)和420 kg N·hm^(-2)(N_(3)),另设置不施氮肥不添加秸秆的对照处理(CK),共10个处理。采集定位试验4年后玉米田间土壤,通过培养试验,探究不同处理对玉米田土壤CO_(2)排放的影响及CO_(2)排放与土壤溶解性有机碳(DOC)和微生物生物量碳(MBC)的关系。结果表明:秸秆还田和氮肥施用均会促进玉米田土壤CO_(2)排放,并随秸秆还田量和施氮量的增加而显著增加,其中氮肥施用是促进玉米田土壤CO_(2)排放的最主要因素;秸秆还田与氮肥配施通过促进微生物生物量增加并加剧DOC消耗来促进玉米田土壤CO_(2)排放;MBC和DOC含量显著刺激玉米田土壤CO_(2)排放,且主要受两者培养前期含量的影响。从保障秸秆还田培肥地力同时减少CO_(2)排放的角度考虑,210 kg N·hm^(-2)常规施氮量与6000 kg·hm^(-2)秸秆还田配合施用(N_(2)S_(2))是本试验条件下辽西北半干旱区最有潜力的田间施肥模式。

Understanding the effects of different amounts of straw returning and nitrogen fertilizer application on soil CO_(2)emission from maize field can provide theoretical support for carbon sequestration and CO_(2)emission reduction and the implementation of black soil region conservation plan.Three rates of straw returning were set up in the semi-arid area of northwest Liaoning Province,China,i.e.3000(S_(1)),6000(S_(2))and 9000 kg·hm^(-2)(S_(3),full amount of straw returned to the field);crossed with three nitrogen fertilizer application rates in the sub-region,respectively,i.e.105(N_(1)),210(N_(2),conventional nitrogen application rate)and 420 kg N·hm^(-2)(N_(3)).In addition,there was a control treatment(CK)without nitrogen fertilizer and straw returning.Soil samples were collected after 4 years field experiment with maize plantation.The influence of different treatments on maize field soil CO_(2)emission and the relationship between CO_(2)emission and soil dissolved organic carbon(DOC)and microbial biomass carbon(MBC)were investigated in an incubation experiment.The results showed that both of straw returning and nitrogen fertilizer application promoted soil CO_(2)emission in maize field,which were increased significantly with the increases of straw returning amount and nitrogen application amount.Nitrogen fertilizer application was the most important factor promoting soil CO_(2)emission in maize field.Straw returning combined with nitrogen fertilizer promoted soil CO_(2)emission by increasing microbial biomass and increasing DOC consumption.MBC and DOC stimulated soil CO_(2)emission significantly in maize field,and were mainly affected by their contents in the early stage of incubation.From the perspective of ensuring the fertilization of straw return to the field while reducing CO_(2)emissions,results from our experiment showed that 210 kg N·hm^(-2)conventional nitrogen application in combination with 6000 kg N·hm^(-2)straw returning(N_(2)S_(2))was the most promising mode in the semi-arid area of northwest Liaoning Province.