摘要
【目的】在陕西关中冬小麦-夏玉米轮作区,研究还田玉米秸秆的氮释放对土壤供氮和冬小麦氮吸收的影响,为优化区域秸秆还田的小麦氮素管理提供理论依据。【方法】田间试验于2012年10月至2013年5月在陕西省周至县终南镇进行,冬小麦播种后,在小麦行间填埋装有风干玉米秸秆的尼龙网袋,采用网袋法与15N同位素交叉标记还田玉米秸秆和氮肥,在秸秆还田条件下,设置不施氮和施氮200 kg N·hm-2两个处理,重复4次,定期取样测定网袋中剩余秸秆的氮素变化和收获期小麦不同器官的氮含量,研究小麦生长季还田玉米秸秆的氮素释放,秸秆氮和肥料氮的去向,及不同来源的氮素对小麦地上部氮吸收的贡献。【结果】残留在玉米秸秆中的总氮量从小麦播种到越冬前降低,此后到返青期上升,返青期后又逐渐下降。从播种至收获,不施氮和施氮量200 kg N·hm-2时,秸秆自身氮素的释放量分别为19.7和18.3 kg·hm-2,吸持的土壤氮为10.4和7.5 kg·hm-2;吸持肥料氮(施氮时)为3.6 kg·hm-2,因此秸秆向土壤净释放的氮素分别为9.4和7.2 kg·hm-2。小麦收获期,不施氮和施氮200 kg N·hm-2时分别有65.1%和67.7%的秸秆氮残留在未腐解的秸秆中,31.5%和30.4%随着秸秆腐解释放进入土壤或损失,小麦当季吸收利用的秸秆氮很少,分别为3.4%和1.9%。秸秆还田条件下,施氮量为200 kg N·hm-2时,经吸收进入小麦地上部、残留于土壤及损失、被玉米秸秆吸持的肥料氮分别占施入土壤肥料氮总量的25.0%、73.2%和1.8%。土壤氮对小麦当季氮吸收的贡献最大,肥料氮次之,秸秆氮的贡献最小,不施氮与施氮时,分别为98.3%和69.2%、0和30.1%,1.7%和0.6%。小麦吸收的土壤、肥料和秸秆氮素主要分配在小麦籽粒中,不施氮与施氮时分别为98.1%和68.8%、0和30.5%、1.9%和0.7%。【结论】在陕西关中冬小麦-夏玉米轮作区,种植一季小麦后,还田秸秆氮主要残留在田间未腐解的秸秆中,占65%以上;肥料氮以残留于土壤或损失为主,高于70%;土壤氮对小麦氮吸收的贡献最大,约为70%。
【Objective】 In order to optimize the nitrogen nutrient management under straw returning to soil condition in the winter wheat-summer maize rotation region of Shaanxi Guanzhong Plain, a field experiment was carried out to study the N release characteristics of maize straw and the effects of returning straw to soil on loess N supply and nitrogen uptake by winter wheat. 【Method】The field experiment was initiated in October 2012 and ended in May 2013 at Zhongnan town, Zhouzhi county in Shaanxi Province. Some little nylon net bags containing the air dried maize straw were buried between the rows after local winter wheat sowing. The experiment was conducted by a combination of net bag buried in the field and 15 N isotope cross labeled maize straw and N fertilizer with four replications. The changes of residual N from the straw and N content in different organs of wheat at harvest were measured for studying the N release of maize straw during the wheat growing season, the fate of straw N and fertilizer N, and their contributions to N uptake in the above-ground part of winter wheat by using two treatments, which were no nitrogen and 200 kg N·hm-2 fertilization under returning straw to soil condition. 【Result】 The amount of total N remained in the straw was decreased from seeding to the period before the winter dormant stage of wheat, then increased until reviving stage and declined gradually later. From sowing to harvest of wheat, the amounts of net N release to soil were 9.4 and 7.2 kg·hm-2 by the returned straw under no and 200 kg N·hm-2 fertilization, respectively, and they were the balance of the N release of 19.7 and 18.3 kg N·hm-2 from the straw, and the N capture of 10.4 and 7.5 kg·hm-2 from the soil and 3.6 kg N·hm-2 from fertilizer into the straw. At harvest, it was found that 65.1% and 67.7% of the straw N were still left in the returned straw, 31.5% and 30.4% were released into the soil or lost, and only a few, 3.4% and 1.9% were absorbed and used by winter wheat, at respectively no N and 200 kg N·ha-1 fertilization. Also, 25.0%, 73.2% and 1.8% of fertilizer N were observed respectively to be absorbed and used by winter wheat, left in the soil or lost, and captured by the returned maize straw under straw returning condition, when the N application rate was 200 kg N·hm-2. Under straw returning condition, soil N was shown to contribute the most to the above-ground part N uptake of wheat, and then was the fertilizer N, while the straw N contributed the least, of which they were 98.3% and 69.2%, 0 and 30.1%, 1.7% and 0.6%, at no N and 200 kg N·hm-2 fertilization, respectively. In the above-ground part of wheat, N derived from soil, fertilizer and straw were mainly distributed in the grain of wheat, and they were respectively 98.1%, 0 and 1.9% at no N fertilization, and 68.8%, 30.5% and 0.7% as N fertilizer was applied into the soil.【Conclusion】In the winter wheat-summer maize rotation region of Shaanxi Guanzhong Plain, more than 65% in straw N was still left in the straw after one winter wheat growing season, also as high as 70% of fertilizer N was mainly immobilized by soil or lost under maize straw returning condition. And soil N contributed the most to the above-ground part N uptake of wheat, which approximated 70%.
出处
《中国农业科学》
CAS
CSCD
北大核心
2015年第14期2785-2795,共11页
Scientia Agricultura Sinica
基金
国家现代农业产业技术体系建设专项(CARS-3-1-31)
国家公益性行业(农业)科研专项(201303104
201103003)
农业科研杰出人才及其创新团队培养计划
西北农林科技大学基本科研业务费专项(Z109021202)
作者简介
联系方式：黄婷苗，E—mail：woshitmiao@163．com。
通信作者 郑险峰，E-mailz．hengxf@nwsuaf．edu．en
