黄土高原旱地夏季休闲期土壤硝态氮淋溶与降水年型间的关系  

The Relationship of NO_3^--N Leaching and Rainfall Types During Summer Fallow in the Loess Plateau Dryland

作　　者：夏梦洁 马乐乐 师倩云 陈竹君 周建斌 XIA MengJie;MA LeLe;SHI QianYun;CHEN ZhuJun;ZHOU JianBin(College of Natural Resources and Environment, Northwest A ＆F University~Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, Yangling 712100, Shaanxi)

机构地区：[1]西北农林科技大学资源环境学院/农业部西北植物营养与农业环境重点实验室,陕西杨凌712100

出　　处：《中国农业科学》2018年第8期1537-1546,共10页Scientia Agricultura Sinica

基　　金：国家自然科学基金(31372137)

摘　　要：【目的】冬小麦-夏休闲是旱地重要的轮作模式之一,随着氮肥用量的增加,一季小麦收获后土壤中残留的硝态氮含量不断增加,夏季休闲期间集中降水的特点是否会导致硝态氮淋溶损失,这一问题值得关注。【方法】连续3年(2013—2015年)采集黄土高原南部长武和杨凌两地夏季休闲前后0—200 cm土壤剖面样品,测定土壤硝态氮含量,研究不同降水年和不同施氮量下黄土高原旱地夏季休闲期间土壤剖面硝态氮累积及淋溶特性。【结果】小麦收获后,长武0—200 cm土壤剖面硝态氮累积量在97—328 kg·hm^(-2),平均193 kg·hm^(-2);杨凌施氮量为120kg N·hm^(-2)及240 kg N·hm^(-2)时,土壤剖面硝态氮累积量分别为156 kg·hm^(-2)及366 kg·hm^(-2),增加施氮量土壤剖面累积硝态氮量显著增加。不同降水年夏季休闲前后硝态氮在土壤剖面的淋溶与降水量密切相关,长武降水量高的丰水年2013年(296 mm)休闲前位于40—60 cm深度的硝态氮累积峰在休闲后到达80 cm以下,淋溶作用明显。而降水量少的欠水年2014年(157 mm)休闲后土壤剖面未发生硝态氮的淋溶。降水量一般的平水年2015年(200mm)休闲后在0—100 cm土壤剖面会发生硝态氮向下淋溶,但是迁移深度不大。在降水量高的2013年夏季休闲后100—200 cm土壤剖面增加的硝态氮累积量是0—100 cm的2.5倍,而2014年夏季休闲后土壤剖面增加的硝态氮累积量主要出现在0—100 cm土壤剖面。杨凌2013年试验期间降水量低(仅220 mm,属欠水年),休闲后两个施氮处理的土壤剖面硝态氮累积峰甚至出现轻微上移;同为欠水年,2015年降水量有所增加(288 mm),休闲后0—100 cm土壤剖面中发生硝态氮下移达到20—40 cm。而降水量更高的2014年(346 mm,平水年),休闲后土壤剖面中硝态氮累积峰较休闲前下移了60—80 cm。相比休闲前,降水量低的2013年夏季休闲后土壤剖面增加的硝态氮累积量主要出现在0�【Objective】 Summer fallow after harvesting winter wheat is very common in dryland of the Loess Plateau. Theresidual nitrate in soil profile after wheat harvest was increased with the application of nitrogen（N） fertilizer. Whether the intensive high rainfall during summer fallow will increase NO3--N leaching loss is an important issue deserving study.【Method】Soil profile samples（0-200 cm） were taken before and after summer fallow in three consecutive years（2013 to 2015） in Changwu and Yangling; NO3--N content in soil was analyzed to evaluate the impact of different precipitations and N application rates on NO3--N leaching during summer fallow. 【Result】 The NO3--N in soil profiles of Changwu was in range of 97 to 328 kg·hm-2, averaged 193 kg·hm-2. The average NO3--N content in soil profiles of 120 and 240 kg N·hm-2 treatments in Yangling was 156 and 366 kg·hm-2, respectively, indicating that NO3--N accumulation in soil was increased with N fertilizer rate. There was significant relationship between NO3--N leaching and rainfall during summer fallow. When rainfall was high（296 mm, abundant rainfall） in 2013 in Changwu, NO3--N accumulation peak leached below 80 cm soil depth from 40-60 cm after summer fallow, indicating strong nitrate leaching. But NO3--N peak didn’t change after summer fallow in 2014 due to the low rainfall（157 mm, deficit rainfall）. The rainfall was normal in 2015（200 mm）, so slight nitrate leaching occurred in 0-100 cm soil profile after summer fallow. Soil nitrate has already leached to 100-200 cm soil profile after summer fallow in 2013 and the accumulation increment was 2.5 times than 0-100 cm soil profile due to high rainfall; but in 2014 soil nitrate accumulation increment was mainly in 0-100 cm soil profile. When rainfall in 2013 was low（only 220 mm, deficit rainfall） in Yangling, NO3--N was found slightly move upward of two N applied treatments. It was deficit rainfall but the rainfall increased to 288 mm in 2015, then nitrate leaching occurred t

关 键 词：旱地 夏季休闲 降水 施氮量 硝态氮淋溶 黄土高原 

分 类 号：S153.6[农业科学—土壤学]