摘要
为明确紫色土有机肥替代化肥的农学与环境效应,减少紫色土氮素面源污染,进一步为紫色土化肥“零增长”策略提供科学依据,利用紫色土坡地养分管理长期试验平台,结合自由排水采集器(Free-drain Lysimeter)定位观测,研究紫色土坡耕地小麦-玉米轮作期间(2012—2013年)不同施肥方式下的土壤无机氮动态、作物产量、氮素流失路径与总量。等氮下设置5个施肥处理:单施化学氮肥(N)、常规化肥(NPK)、猪厩肥(猪厩肥替代100%的化肥氮,OM)、猪厩肥与氮磷钾配施(猪厩肥替代30%的化肥氮,OMNPK)、秸秆还田与氮磷钾配施(秸秆替代15%的化肥氮,CRNPK),以不施肥(NF)为对照。结果表明,紫色土坡耕地壤中流流量占总径流量的54.5%~84.6%,随壤中流淋失的氮占氮流失总量的90.6%,以壤中流为介导的氮淋失是紫色土坡耕地氮素流失的首要途径,且氮淋失量高达12.53~76.72 kg(N)·hm^(-2),远高于我国其他地区农田氮淋失量,紫色土地区是氮淋失的热点区域。与常规施肥(NPK)相比,有机肥替代化肥显著降低紫色土氮素流失量,其中猪厩肥(OM)、猪厩肥与氮磷钾配施(OMNPK)、秸秆还田与氮磷钾配施(CRNPK)总氮素流失量分别减少32.1%(P<0.05)、27.5%(P<0.05)与21.2%(P<0.05),其关键机制在于有机肥替代化肥对氮淋失的减控作用,通过壤中流淋失的氮素分别减少32.0%(P<0.05)、26.7%(P<0.05)与18.0%(P<0.05);此外,氮流失系数分别降低44.8%、38.5%及24.3%,玉米-小麦轮作系统年产量分别增加23.0%、17.8%及4.1%。因此,长期有机肥替代化肥能在减量施用化肥的基础上保证作物产量,同时显著降低紫色土坡耕地氮流失风险,是当前紫色土坡耕地可推荐的减氮增效技术。
Excessive N fertilizer application not only increases crop productivity,but also induces substantial environmental N losses that cause large environmental pollution risks.This study aimed to examine the effects of substituting synthetic N fertilizers with organic fertilizers on the reduction in environmental N losses from croplands in purple soil areas.Therefore,we conducted a one year field investigation to measure N-loss pathways and fluxes,crop productivity,and soil environmental variables in a wheat-maize rotation system under long-term different fertilization regimes with the same N rate,including the control(no fertilizer;NF);synthetic N fertilizer only(N);pig manure substituting 100% synthetic N fertilizer(pig manure;OM);regular synthetic N,P,and K fertilizer(NPK);combination of pig manure with synthetic N,P,and K fertilizer(OMNPK;pig manure substituting 30% synthetic N fertilizer);and combination of straw residue returned with synthetic N,P,and K fertilizer(CRNPK;straw residue substituting 15% synthetic N fertilizer).The results showed that N losses via surface runoff and sediment were in the range of 1.12-3.52 kg(N)·hm^(-2) and 1.48-7.26 kg(N)·hm^(-2),respectively.The N leaching losses via interflow ranged from 12.53 to 76.72 kg(N)·hm^(-2),which were over 10 times greater than those for surface runoff;nevertheless,N leaching losses accounted for 90.6% of the total hydrological N losses.These results indicate that N leaching via interflow is the predominant pathway of hydrological N losses,thereby highlighting that sloping cropland of purple soil is one of the hotspots of N leaching losses from agricultural soils in China.Compared with that of the NPK treatment,the substitution of synthetic N fertilizer with organic fertilizers(OM,OMNPK,and CRNPK treatments)decreased the total hydrological N losses by 32.1%,27.5%,and 21.2%,respectively.This was mainly because practices with substitution of synthetic N fertilizer with organic fertilizers significantly decreased N leaching losses via interflow compared with the application of synthetic N fertilizer only.Furthermore,considering the crop yields,the substitution of synthetic N fertilizer with organic fertilizer treatments(OM,OMNPK,and CRNPK treatments)significantly increased the total annual crop yields by 23.0%,17.8%,and 4.1%,respectively,and decreased the yield-scaled total hydrological N losses by 24.3% to 44.8%.Therefore,the long-term substitution of synthetic N fertilizer with organic fertilizer can not only increase the crop productivity of both wheat and maize,but also decrease environmental N losses,thereby decreasing the risk of agricultural non-point source pollution in the purple soil region.Overall,the substitution of synthetic N fertilizer with organic fertilizers can be recommended as an optimized agricultural N management strategy to reduce synthetic N fertilizer rates and improve N use efficiency in agricultural systems of the purple soil region.
作者
胡冬妮
董志新
朱波
HU Dongni;DONG Zhixin;ZHU Bo(Institute of Mountain Hazards and Environment,Chinese Academy of Sciences/Key Laboratory of Mountain Surface Processes and Ecological Regulation,Chinese Academy of Sciences,Chengdu 610041,China;University of Chinese Academy of Science,Beijing 100049,China)
出处
《中国生态农业学报（中英文）》
CAS
CSCD
北大核心
2022年第3期431-440,共10页
Chinese Journal of Eco-Agriculture
基金
国家自然科学基金项目(U20A20107)资助。
关键词
紫色土
坡耕地
壤中流
氮流失
氮淋失
有机肥
优化施肥
Purple soil
Sloping cropland
Interflow
Nitrogen loss
Nitrogen leaching
Organic fertilizer
Improved fertilization
