华北平原春玉米季土壤硝态氮动态及氮素矿化的特征

Characteristics of Soil NO_3^- -N Changing and Nitrogen Mineralization During Spring Maize Seasons in the North China Plain

为进一步明确推荐施氮的优势所在,并为春玉米制定合理的施氮策略,本文在高肥力土壤条件下,通过设计不同氮肥管理模式.研究了春玉米季0—150 cm土体土壤NO_3^-—N动态和氮素矿化的特征。结果表明,经验施氮0—90 cm土层NO_3^-—N含量呈单峰曲线变化,峰值一般在400 kg/hm^2以上,90—150 cm土层则富积了大量的NO_3^-—N,潜在淋洗量很大。不施氮条件下,土壤表现出较强的净矿化势,并且净矿化速率和玉米生长速率有较好的协同性,二者同在大喇叭口至吐丝期达到最大值,但土壤供氮能力逐年下降。推荐施氮使得0—90 cm土层NO_3^-—N总体保持在100～200 kg/hm^2范围内,既确保作物的吸收又减少了氮素淋洗损失。研究表明,三年来推荐施氮共节省氮肥475 kg/hm^2,氮肥利用率提高了14%。

Relating to recommended nitrogen fertilization （RNF）, soil NO3^-- --N dynamics and nitrogen mineralization in the North China Plain, most former research focused on winter wheat and summer maize, whereas almost no research involved spring maize. In order to further understand the advantages of RNF, and make the nitrogen fertilization strategy in spring maize season more reasonable. A field experiment included three nitrogen managements （zero nitrogen fertilization, ZNF; traditional nitrogen fertilization, TNF; recommended nitrogen fertilization, RNF） focusing on characteristics of soil NO3^--N dyna mics and nitrogen mineralization was conducted from 2005 to 2007 in Dongbelwang experimental station. In TNF, NO3^- -N content in 0-90 cm soil level showed a single peak curve, and the peak value was over 400 kg/hm^2. An accumulation of NO3^- --N in 90-150 cm soil level was also found in TNF, that making a great threaten of nitrogen leaching. ZNF presented a strong net nitrogen mineralization tendency, and a cooperativity between net N mineralization rate and plant growth rate was also found, however the soil nitrogen supplying capacity declined annually. In RNF, NO3^- --N content in 0-90 cm soil level was controlled in the range of 90-220 kg/hm^2 , that not only ensured plants uptake normally, but also decreased N-leaching loss. In the three years, RNF saved 475 kg/km^2 nitrogen fertilizer totally, and improved nitrogen use efficiency 14%.