西藏草地开垦后土壤表层氮素及有机碳特征研究

选取西藏琼结县和江孜县2个地区不同开垦年限耕地表层的土壤作为研究对象,分析其土壤中氮素及有机碳(SOC)含量特征变化状况。结果表明,草地开垦为耕地后,土壤表层全氮(TN)及有机碳(SOC)含量前2年内先降低,而后随着开垦年限增加有逐渐增高的趋势,大体呈"V"字型变化趋势,铵态氮(NH4+-N)大体上也呈相似的变化趋势,而硝态氮(NO3--N)随着开垦年限增加则无明显变化规律。2个地区耕地表层铵态氮、全氮与有机碳之间均呈显著正相关关系(P0.01),而硝态氮与有机碳相关性不显著(P0.05)。

Study on the dynamics of nitrogen and organic carbon in soil of cultivated grassland in Tibet

Surface soil of arable land in different reclamation duration in Qiongjie and Jiangzi of Tibet was sampled to study the dynamics of nitrogen and organic carbon. The results showed that the total nitrogen and soil organic carbon (SOC) content of the topsoil of the farmland decreased within the first two years and then increased in the following years, which presented roughly a V shaped trend. Generally the ammonium nitrogen (NH4+ N) showed same trend, but the nitrate nitrogen (NO3- N) had no significant variation with increasing of arable years. Ammonium nitrogen, total nitrogen and SOC in the surface soil of both regions showed a significant positive correlation (P<0.01), but no significant correlation (P>0.05) between nitrate nitrogen and SOC.