不同作物对旱地农田残留硝态氮的利用差异  

A comparison of the use of residual soil nitrate by winter wheat and alfalfa in the drylands of China's Loess Plateau

作　　者：李云[1,2] 刘炜 王朝辉[1] 高亚军[1,4] 

机构地区：[1]西北农林科技大学资源环境学院,杨凌712100 [2]四川农业大学资源环境学院,成都611130 [3]陕西省宝鸡市农技推广服务中心,宝鸡721000 [4]农业部西北植物营养与农业环境重点实验室,杨凌712100

出　　处：《生态学报》2014年第13期3788-3796,共9页Acta Ecologica Sinica

基　　金：公益性行业(农业)科研专项(201103005);国家小麦现代产业技术体系建设专项经费;农业科研杰出人才及其创新团队培养计划;教育部"新世纪优秀人才支持计划"项目(NCET-08-0465)

摘　　要：在黄土高原南部娄土上,通过2a田间试验研究了小麦和苜蓿对土壤中不同累积量的残留硝态氮的利用差异。研究包括0—3 m土壤残留硝态氮累积量(设N1、N2、N3、N4、N5和N6共6个水平,残留硝态氮量依次增加)和作物种类(冬小麦和苜蓿)2个因素,分别采用冬小麦-夏休闲-冬小麦和苜蓿连作种植方式。结果表明,不施用氮肥条件下,冬小麦-休闲-冬小麦轮作周期与苜蓿连作2a内,土壤残留硝态氮的消长有明显差异。在第1季小麦生长期间,小麦的氮素携出量(63.9—130.3 kg/hm2)、氮素携出量占播前残留硝态氮量的比例(18%—27%)及氮素携出量占该生长季硝态氮减少量的比例(29%—62%)均显著高于同期的苜蓿处理。在第2个生长季内,苜蓿的氮素携出量是小麦当季氮素携出量的近6倍,但由于苜蓿固氮作用强烈,至第2生长季结束后,0—3 m土壤硝态氮量与苜蓿播前相比平均只减少了72.4 kg/hm2,而麦田0—3 m土壤硝态氮量与小麦播前相比减少了158.3 kg/hm2。在短期内如果通过种植作物消耗土壤剖面的残留硝态氮,冬小麦比苜蓿更有优势。第1季小麦氮素携出量与小麦播前0—2 m(r=0.920**)和0—3 m(r=0.857*)土层残留硝态氮量呈显著或极显著正相关,与0—1 m土层残留硝态氮量没有显著相关性;第1生长季苜蓿氮素携出量与播前0—1 m土壤硝态氮累积量呈显著正相关关系(r=0.846*),而与0—2 m和0—3 m土壤硝态氮累积量的相关性并不显著。小麦比苜蓿能利用更深土层中的硝态氮。随着播前0—3 m土壤残留硝态氮的增加,小麦和苜蓿地上部氮素携出量呈增加的趋势,硝态氮表观损失也显著增加。The application of excessive amounts of nitrogen fertilizer in dryland habitats continues to result in an increase in the amount of residual nitrate found in dryland soil profiles in the southern Loess Plateau of north central China. Efforts to use this resource have attracted considerable attention. A two-year field experiment was conducted in the southern Loess Plateau to investigate and compare how residual soil nitrate is used in winter wheat and alfalfa fields. Crops of alfalfa and winter wheat were grown in fields with six levels of residual soil nitrate,measured as the accumulated nitrate at soil depths of 0—3 m,with continuous alfalfa and wheat-summer fallow-wheat systems. Both crops exhibited similar yet different changes in the levels of residual soil nitrate during the two year study without the application of additional nitrogen fertilizer.During the first wheat growing season,soil nitrate at a depth of 0—3 m decreased by 42% —66% in the wheat fields while it decreased by 41% —73% in the alfalfa fields,compared with N levels before sowing. N uptake（ 63. 9—130. 3 kg /hm2）,the proportion of N uptake from the total residual soil nitrate prior to crop sowing（ 18%—27%）,and the proportion of N uptake from soil nitrate reduction（ 29% —62%） was much higher for winter wheat than for alfalfa. The apparent reduction of soil nitrate in the upper 0—3 m of soil in the wheat field（ 62. 1—317. 1 kg /hm2） was lower than that in the alfalfa field（ 95. 0—614. 1 kg /hm2）. During the second wheat growing season,N uptake of alfalfa was 593.8 kg/hm2,six times higher than the N uptake of wheat. However,residual soil nitrate in the alfalfa treatments increased as a result of strong N fixation by alfalfa. Compared with the N levels prior to crop sowing,the residual soil nitrate in the alfalfa field declined by 72. 4 kg /hm2 while it declined by 158. 3 kg /hm2 in the wheat field after two growing seasons. These results indicate that winter wheat used more residual soil nitrate than alfalf

关 键 词：残留硝态氮 冬小麦 苜蓿 旱地 

分 类 号：S153.6[农业科学—土壤学]