旱地土壤中残留肥料氮的动向及作物有效性  

Dynamics and Availability to Crops of Residual Fertilizer Nitrogen in Upland Soil

作　　者：王西娜[1,2] 王朝辉[1] 李华[1] 王荣辉[1] 谭军利[1,3] 李生秀[1] 

机构地区：[1]西北农林科技大学资源环境学院,陕西杨凌712100 [2]宁夏大学农学院,银川750021 [3]宁夏大学土木与水利工程学院,银川750021

出　　处：《土壤学报》2016年第5期1202-1212,共11页Acta Pedologica Sinica

基　　金：国家自然科学基金项目(31460546);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)资助~~

摘　　要：氮素是作物生长最重要的必需元素之一。合理施用氮肥能促进作物生长并提高产量,但是,过多施用氮肥则抑制作物生长并导致大量的肥料氮残留在土壤中,这部分氮素不但会引起土壤养分不平衡,而且为生态环境带来潜在威胁,因此,研究残留氮的动向及作物有效性可为合理施用化肥氮、高效利用土壤残留氮素和减少残留氮素的损失提供依据。应用^(15)N示踪技术,通过4年定位试验,研究了黄土高原南部旱地冬小麦/夏玉米轮作过程中土壤残留肥料氮的变化及作物吸收利用。在冬小麦和夏玉米轮作的第一个周期,为了制造高肥料氮残留背景,于冬小麦播种前向微区施入240 kg hm^(-2)的^(15)N标记氮素;在夏玉米拔节期,为了研究氮肥施入对残留肥料氮的影响,设置0和120 kg hm^(-2)两个氮水平,以普通尿素施入微区。在第2至第4个轮作周期内,为了分析残留肥料氮的动向及其对作物的有效性,微区内不施任何肥料。结果发现,冬小麦播种前施用的^(15)N标记氮肥于收获期在0~200 cm土壤剖面中均有残留,但大部分累积在0~40 cm土层中,累积总量达到200.9 kg hm^(-2),占当季施入量的83.7%。在随后的夏玉米生长季残留的肥料氮迅速减少,之后随生长季的后移缓慢减少,然后保持相对稳定。经过4年的冬小麦/夏玉米轮作,0~300 cm土壤剖面仍残留大量的^(15)N肥料,后季不追施氮肥和追施氮肥处理的残留量分别为47.1 kg hm^(-2)和54.0 kg hm^(-2)。可见,有一部分肥料氮被固定在土壤有机质中。作物对残留氮的回收量逐年减少,且因后季追施氮肥与否而异,4年中作物对肥料氮的总利用率不追施氮肥和追施氮肥处理的分别为46.9%和50.4%,其中在第1个轮作周期中,小麦和玉米的总利用率分别41.6%和42.0%,后3年利用率分别仅有5.3%和8.4%;4年中残留^(15)N的损失率分别达38.1%和29.7%,其损失主要发生在第1个轮作周期的夏玉米�【Objective】Nitrogen is one of the most important and essential elements for growth of crops. Reasonable application of nitrogen fertilizer may promote crop growth and increase its yield,while excessive N fertilization may not only inhibit crop growth,but also leave a large amount of fertilizer nitrogen（N）in the soil as residue,which disturbs balance of soil nutrients and poses a potential threat to the ecological environment. So,it is necessary to study dynamics and availability to crops of the residual N to provide a theoretical basis for rationalizing N fertilization,improving N use efficiency and reducing fertilizer N loss. 【Method】To that end,a 4-year stationary field experiment was carried out on a winter wheat and summer maize rotation system,using^15N-tracing technique. During the first cycle of the winter wheat and summer maize rotation,240 kg hm^-2 of nitrogen was applied in the form of ^15N-laballed urea in all the plots before winter wheat was sown,in order to make a background of high N residual,and in the following summer maize season,the plots were divided into two groups applied with 0 and 120 kg hm^-2 of ordinary urea,separately,at the prolonging stage of the crop to explore effect of N fertilizer application on fertilizer N residue in the soil. During the following three cycles of the rotation,no N fertilizer was applied for analysis of dynamic and availability to the crops of the residual fertilizer N in the soil. 【Result】Results show that residue of the ^15N laballed N fertilizer that was applied before sowing of winter wheat during the first cycle of the rotation,was found throughout the whole soil profiles of 0～200 cm,after the crop was harvested,and most of that accumulated in the 0～40 cm soil layers. The residue amounted to 200.9 kg hm^-2 in total,accounting for 83.7% of the total N fertilizer applied. In the subsequent summer maize growth season,the amount of residual fertilizer N first dropped rapidly,and then declined slowly with the season going on,and eventually lev

关 键 词：旱地土壤 ^15N示踪 残留肥料氮 作物有效性 氮素损失 

分 类 号：S138.3[农业科学—农业基础科学]