苜蓿草地土壤氮矿化的研究  

Nitrogen mineralization in alfalfa stands

作　　者：韩方虎[1] 沈禹颖[1] 王希[1] 周少平[1] 杨晶[1] 耿丽英[1] 

机构地区：[1]兰州大学草地农业科技学院农业部草地农业生态系统学重点实验室,甘肃兰州730020

出　　处：《草业学报》2009年第2期11-17,共7页Acta Prataculturae Sinica

基　　金：973项目(2007CB106804);澳大利亚国际农业中心项目(LWR2/1999/094);中澳政府间科技合作项目(2005DFA30030-6);农业部草地农业生态系统学重点实验室资助

摘　　要：12周温室培养条件下，研究了淋洗起始矿质氮、施N和植被覆盖对庆阳黄土高原5龄和9龄苜蓿草地土壤氮矿化的影响。结果表明，起始无机氮对土壤N矿化有一定的抑制作用，去除起始无机氮后，N净矿化率提高了0．05～0．07mg／（kg·d）。添加外源N肥使5龄苜蓿草地NO3^--N含量增加了56倍，N净矿化率提高了200％；9龄苜蓿草地NO3^--N含量仅增加了2倍，N净矿化率降低了62．5％。植被覆盖对土壤N净矿化率有显著影响，N净矿化率比对照提高了12～18倍。施N肥且覆盖植被使N净矿化率提高了18～25倍。9龄苜蓿土壤的矿化能力显著高于5龄苜蓿土壤。在草田轮作系统中，苜蓿土壤翻耕后不宜休闲，应立即种植后续作物，可减少雨季土壤表层氮的淋失，提高氮素有效性。Greenhouse incubation experiments （12 weeks） were used to explore the influence of leaching initial mineral N, N fertilizers, and vegetation coverage on soil nitrogen mineralization of 5- and 9-year alfalfa （Medicago sativa） grasslands in the Qingyang Loess Plateau. The initial mineral N affected N mineralization and the net N mineralization rate increased by 0.05-0.07 mg/（kg · d） after the initial N was taken away. When N fertilization was adopted, the content of NO3^ --N in 5- and 9-year alfalfa grassland increased by 56 and 2 times respectively and net N mineralization rate increased by 200% in 5-year alfalfa grassland, but decreased by 62.5 % in 9-year alfalfa grassland. Moreover, planting ryegrass （Lolium perenne） significantly affected N mineralization rate. For instance, net N mineralization rates in treatments with ryegrass were 12 to 18 times higher than in the control, and reached the highest values in the treatment N＋Rye, where they were 18 to 25 times higher than in the controls. N mineralization potential in 9-year alfalfa stands was higher than in 5-year alfalfa. In grass-crop rotation systems on the Loess Plateau, succession is removed as dense plant coverage should reduce the risk of los plants should be sowed ing NO^3-and thus enha immediately after alfalfa nce N availability in the rainy season.

关 键 词：黄土高原 淋洗 施N 植被覆盖 土壤N净矿化率 

分 类 号：S541.9[农业科学—作物学]