作　　者： ; ; ; ; ; ;

机构地区： 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开放实验室

出　　处： 《草业学报》 2009年第2期11-17,共7页

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 植被覆盖 土壤 净矿化率

领　　域： [农业科学] [农业科学] [农业科学]