PDF《西藏高原日光温室菜地土壤碳、氮矿化特征研究*》

0.05). There was no significant difference between the 1-year greenhouse and 5-year greenhouse soil conditions in terms of carbon mineralization (P >

0.05). This was attributed to soil nutrient and soil microbial environment sensitivity to temperature. Soil CO2-C accumulation in farmland soil was higher than in alpine grassland soil. It was also higher in alpine grassland soil than in the 1-year greenhouse and 5-year greenhouse soils. However, the differences in soil organic carbon mineralization and accumulation among alpine grassland, farmland, 1-year greenhouse and 5-year greenhouse soil conditions were not significant (P >

第11 期 马丽娜等: 西藏高原日光温室菜地土壤碳、氮矿化特征研究

1341 0.05) at

28 days after treatment. Soil nitrogen mineralization mainly happened in different soil types during the first three days (3 d) after treatment. With delayed incubation, the main process of soil nitrogen mineralization was nitrogen fixation. Soil inorganic nitrogen content in alpine grassland, farmland, 1-year greenhouse and 5-year greenhouse soils at

28 days after incubation were 29.04%, 75.94%, 66.86% and 65.70% of that at

0 day, respectively. The results showed that soil nitrogen mineralization capacity of alpine grassland soil was stronger than farmland, 1-year greenhouse and 5-year greenhouse soils. Soil nitrogen mineralization capacity of farmland was weaker than alpine grassland, 1-year greenhouse and 5-year greenhouse. Also soil nitrogen mineralization capacities of 1-year greenhouse and 5-year greenhouse were similar. Moreover, soil mineralization processes were similar among different soil conditions. Key words Alpine region, Grassland, Farmland, Vegetable field under greenhouse, Carbon and nitrogen mineralization (Received May 11, 2013;

accepted Jul. 9, 2013) 近年来随着蔬菜需求量激增和种植业结构调整, 我国西藏地区蔬菜种植面积迅速增加. 截至

2010 年, 西藏地区蔬菜种植面积由

1980 年的

7 700 hm2 增加 至21

300 hm2 , 占农作物总种植面积的百分比由 3.5%提高到 8.9%(全国平均 11%).除露地蔬菜供应 外, 塑料大棚和日光温室等设施蔬菜生产在高原地 区得到推广, 实现了反季节蔬菜的供应[1] . 蔬菜种植 面积的增加与种植技术的提高, 解决了高寒地区吃 菜难的问题.目前西藏市场上 85%左右的蔬菜为本 地产品, 蔬菜供应实现了基本自给.随着人口增加 和城镇化的进程, 西藏地区人民对蔬菜的需求将越 来越大, 这不仅要求继续扩大蔬菜种植面积, 而且 需要进一步提高蔬菜作物单产[1] .增加养分投入是 提高蔬菜单产的一个主要途径.然而, 高寒地区生 态脆弱敏感, 高投入的种植管理体系的迅速介入将 会对土壤质量以及环境造成影响.近30 年来, 由于 耕地面积的增加, 青藏高原草地土壤由于土地利用 变化所释放的 CO2 约有 0.7*108 t[1] .尽管这一值远 远低于由于草地退化所释放的 CO2 29.53*108 t[1] , 但随着人口增加, 耕地面积的继续扩大, 种植模式 的多种多样, 集约化程度的提高, 特别是当低投入 的草地和农田向高投入的菜地转换时, 这部分土壤 有机碳储量的去向及其稳定性机制将变得更加复杂 和不确定. 土壤障碍和环境污染问题是设施蔬菜地产业可 持续发展的瓶颈[2] .土壤碳、氮一直是造成设施菜 地土壤质量和环境问题的核心要素[2] .尽管西藏地 区设施蔬菜地发展历史较短, 由于其自身土壤母质 的中性特质, 在大量氮肥施用和灌溉下, 土壤酸化 程度比石灰性土壤更为突出, 种植