紫云英替代化学氮肥影响红壤水稻土团聚体组成及有机碳分布特征  

Effects of chemical fertilizer substitution of milk vetch on aggregate composition and organic carbon distribution in red paddy soil

作　　者：刘淑军 周玲红 唐利忠 李纲[4] 高学成 黄晶 高菊生 LIU Shujun;ZHOU Linghong;TANG Lizhong;LI Gang;GAO Xuecheng;HUANG Jing;GAO Jusheng(Hengyang Red Soil Experimental Station,Chinese Academy of Agricultural Sciences/National Observation Station of Qiyang Agri-Ecology System,Qiyang 426182,China;Agricultural and Rural Bureau of Shigu District,Hengyang 421001,China;Yongzhou Institute of Agricultural Sciences,Yongzhou 425100,China;Yongzhou Vocational Technical College,Yongzhou 425000,China)

机构地区：[1]中国农业科学院衡阳红壤实验站/祁阳农田生态系统国家野外观测研究站,湖南祁阳426182 [2]衡阳市石鼓区农业农村局,湖南衡阳421001 [3]永州市农业科学研究所,湖南永州425100 [4]永州职业技术学院,湖南永州425000

出　　处：《土壤与作物》2023年第1期25-33,共9页Soils and Crops

基　　金：国家绿肥产业技术体系(CARS-22-Z09);湖南省自然科学基金项目(2022JJ30648);国家水稻产业技术体系(CARS-01-88);中央级公益性科研院所基本科研业务费专项Y2022LM25.

摘　　要：为研究红壤双季稻田紫云英还田替代化学氮肥后土壤团聚体组分及土壤有机碳分布特征,基于2008年开始的紫云英替代化学氮肥定位试验,选择稻-稻-冬闲[常规施肥,NPK(闲)]、稻-稻-紫云英[常规施肥,NPK(紫)]、稻-稻-紫云英[早稻和晚稻均减施20%化学氮肥,0.8N+PK(紫)]和稻-稻-紫云英[早稻和晚稻均减施40%化学氮肥,0.6N+PK(紫)]等4个处理,采用湿筛法对土壤进行团聚体分级,并测定不同粒径团聚体中土壤有机碳含量。结果表明,紫云英还田后,调节氮肥用量显著改变了土壤团聚体组成。平均重量直径(MWD)、几何平均直径(GMD)和>0.25 mm粒级团聚体含量均以NPK(紫)处理最高。与冬闲处理相比,NPK(紫)处理可使>2 mm和0.25~2 mm团聚体含量提高了15.3%和3.81%。紫云英还田后,与NPK(紫)处理相比,0.8N+PK(紫)和0.6N+PK(紫)处理>2 mm团聚体含量显著降低了41.8%~57.6%(P<0.05)。与冬闲处理相比,冬种紫云英还田并减少氮肥用量显著降低了各粒级团聚体中土壤有机碳含量(P<0.05),但冬种紫云英还田各处理间各粒级团聚体中土壤有机碳含量未见显著差异。NPK(闲)处理不同粒径团聚体中有机碳富集系数均>1,NPK(紫)、0.8N+PK(紫)和0.6N+PK(紫)处理>2 mm和0.25~2 mm团聚体中的有机碳富集系数>1。土壤MWD和GMD与>2 mm团聚体和0.25~2 mm团聚体含量呈显著正相关关系(P<0.05),而与团聚体不同粒级中土壤有机碳含量的相关性不显著。可见,在红壤双季稻田进行冬种紫云英还田,有利于优化土壤结构,但不论减氮与否,同时需调节适宜的外源投入碳氮比,从而实现土壤结构稳定和肥力提升。An experiment with milk vetch input to replace chemical nitrogen fertilizer was established in 2008.This study investigated the soil aggregate composition and soil organic carbon distribution with the wet screening method to classify the aggregates and determine the soil organic carbon content of aggregates with different particle sizes.Four treatments were selected,i.e.rice-ricewinter fallow[conventional fertilization,NPK(fallow)],rice-rice-milk vetch[conventional fertilization,NPK(milk vetch)],rice-rice-milk vetch[20%chemical nitrogen reduction for both early and late rice,0.8N+PK(milk vetch)]and rice-rice-milk vetch[40%chemical nitrogen reduction for both early and late rice,0.6N+PK(milk vetch)].The results showed that the soil aggregate composition was significantly changed by adjusting nitrogen application rate.Mean weight diameter(MWD),geometric mean diameter(GMD)and>0.25 mm soil aggregate content were the highest in the treatment of NPK(milk vetch).Compared with winter fallow treatment,the contents of>2 mm and 0.25~2 mm aggregate in the treatment of NPK with milk vetch returned to the field increased by 15.3%and 3.81%,respectively,but there was no significant difference.Compared with the normal nitrogen application,the content of>2 mm aggregate was significantly reduced by 41.8%~57.6%in the treatment of 0.6N+PK(milk vetch)and 0.8N+PK(milk vetch)(P<0.05).Compared with winter fallow treatment,amendment of milk vetch to field together with the reduction of nitrogen application significantly reduced soil organic carbon content in aggregates of all particle sizes(P<0.05).However,there was no significant difference in soil organic carbon content in aggregates among treatments after milkvetch returned to the field.The enrichment coefficients of organic carbon in aggregates with different particle sizes treated with NPK(fallow)were all greater than 1.The enrichment coefficients of organic carbon in aggregates>2 mm and 0.25~2 mm treated with NPK(milk vetch),0.8N+PK(milk vetch),and 0.6N+PK(milk vetch)were greater th

关 键 词：红壤性水稻土 紫云英 减氮 土壤团聚体 土壤有机碳 

分 类 号：S158.3[农业科学—土壤学]