Effects of adding water on seasonal variation of soil nitrogen availability under sandy grasslands in semi-arid region

添加水对半干旱区沙质草地土壤氮有效性季节变化的影响(英文)

Water is usally thought of a limiting factor for the restoration of semi-arid ecosystem. In the growing season of 2006, a study was conducted to determine the effects of modeling precipitation on seasonal patterns in concentrations of soil-available nitrogen and to describe the seasonal patterns in soil nitrogen availability and seasonal variation in the rates of net nitrogen mineralization of topsoil at Daqinggou ecological station in Keerqin sand lands, Inner Mongolia Autonomous Region, China. Manipulation of water （80 mm） was designed to be added to experiment plots of sandy grasslands in dry season. Water addition （W） treatment and control （CK） treatment were separately taken in six replications and randomly assigned in 12 plots （4 m×4 m for each） with 2-m buffers betweens. Results showed that the content of soil inorganic nitrogen and net nitrogen mineralization rate were not affected by adding water in sandy grassland of Keerqin sand lands. Net ni- trogen mineralization rates ranged from 0.5μg·g^-1,month^-1 to 4 μg.g^-1.month^-1. The highest values of soil inorganic nitrogen and net nitrogen mineralization occurred on October 15 in control plots. The seasonal changes of soil inorganic nitrogen contents exhibited ＂V＂ shape pattern that was related to seasonal patterns of soil ammonium-N （ascending trend） and nitrate-N transformation （descending trend）.

水在半干旱地区的生态系统恢复是个限制因素。针对沙质草地干旱期模拟降水对土壤氮有效性影响的问题,采用田间实验添加水的方法,以地处科尔沁沙地的大青沟沙地生态实验站为平台,研究了2006年生长季沙质草地土壤有效氮含量及净氮矿化速率的季节变化。干旱期添加水(80mm)和对照(CK)处理各重复6次,随机分配在12个4m×4m的样方中,样方之间缓冲带宽2m。根据添加水的实验结果,该沙质草地土壤矿质氮含量与净氮矿化速率并未受添加水的影响;净氮矿化速率变化范围在0.5 μg·g-1·month-1至4 μg·g-1·month-1之间;土壤矿质氮含量与净氮矿化速率最高值出现在10月15日的对照处理中。该沙质草地土壤铵态氮的变化随季节上升,硝态氮随时间逐渐降低,而矿质氮的季节变化格局呈"V"型。