草原火烧后土壤养份含量的变化

Burning Effects on Soil Nutrients in a Hulunbeier Grassland

草原不同时间、不同频次火烧后，土壤的金属元素和营养物质发生很大变化．火烧后，土壤中大多数金属元素和表层水解性氮含量有所增加，而速效钾、全氮和金属铜含量有所降底．火烧后，铁、钾和镁在土壤中有一明显积累层，该层随时间推移而下移．

Following grassland burning in Hulunbeier steppe,the soil nutrients changed. Different burning time and different burning frequency caused different results.In general,metal elements in soil and hydrolysis nitrogen in soil surface increased.But total nitrogen ,instant potassium and cooper decreased.In burned site, iron, potassium and magnesium had obvious accumulative layer on profile.