火烧对草地土壤氮总矿化、硝化及无机氮消耗速率的影响

Effect of prescribed burning on grassland nitrogen gross mineralization and nitrification.

采用同位素15N库稀释技术结合扰动较小的管型取样法 ,测定了羊草草地火烧区与未烧区不同季节土壤氮的总矿化速率、总硝化速率、无机氮消耗速率 .结果表明 ,火烧地的氮总矿化与硝化速率在牧草返青后的 4、5月份均高于未烧地 ,7月份差异不显著 ,到生长季末的 9月份又低于未烧地 ;火烧地NH4 + N的消耗速率 7月份以前均高于未烧地 ,9月份低于未烧地 ,NO3- N的消耗 4、5份火烧地要高于未烧地 ,7、9月份又低于未烧地 ;火烧地土壤NH4 + N含量在 4、5和 7月份均高于未烧地 ,9月份基本没有差别 ,而NO3- N在 4、5月份无大差别 ,7。

The seasonal dynamics of nitrogen gross mineralization, nitrification,and mineral nitrogen consumption rates in burned and unburned Leymus chinensis grasslands were studied with 15 N pool dilution technique . The results indicated that the gross mineralization and nitrification rates in burned area were higher than those in unburned area in April and May, and lower than those in unburned area in September. NH 4 + N consumption rates were higher than unburned area in April and May, and lower in September. NO 3 - N consumption rates were higher than control in April and May, and lower than control in July and September. The NH 4 + N concentrations were higher in burned area in April, May and July, and no difference in September.NO 3 - N concentrations were no difference between burned and unburned areas in April and May, and higher in burned areas in July and September.