模拟干湿条件下鄱阳湖灰化薹草生长区土壤氮含量

Nitrogen Content in Soil of Carex cinerascens Distribution Area in Poyang Lake under the Simulated Dry and Wet Conditions

于2015年11月25日,在鄱阳湖湿地灰化薹草（Carex cinerascens）集中生长区,采集0-10 cm深度土壤和植物样品。于2015年12月15日-2016年3月21日,在河南大学环境科学实验室,进行室内模拟实验,研究恒干、恒湿、干湿交替、水位上升、水位下降及添加灰化薹草碎末处理下,土壤中不同形态氮的含量。结果表明,土壤全氮初始平均质量比为1403.7 mg/kg,实验结束时,在未添加灰化薹草碎末的恒干、恒湿、干湿交替、水位上升和水位下降处理下,土壤全氮平均质量比分别为1413.3 mg/kg、1358.0 mg/kg、1325.0 mg/kg、1414.7 mg/kg和1446.0 mg/kg;添加灰化薹草碎末的干湿交替、水位上升和水位下降处理下,土壤全氮平均质量比分别为1612.3 mg/kg、1329.3 mg/kg和1395.7 mg/kg。与实验初始相比,添加灰化薹草的恒湿和干湿交替处理下,0-2 cm深度土壤全氮含量减小了10.9%,恒湿处理下,0-2 cm深度土壤铵态氮含量增幅最大。在灰化薹草分解过程中,2-5 cm深度土壤全氮、铵态氮和硝态氮含量都增大,但是,在添加灰化薹草碎末的各处理下,0-2 cm深度土壤全氮和有机氮含量小于未添加处理,灰化薹草分解提供了丰富的碳源,使土壤中微生物的活性增强。

On Novermber 25, 2015, the samples of surface soil and plant were collected in Carex cinerascens distribution area in Poyang Lake, and the simulation experiments were carried out at the environmental science laboratory of Henan University from December 15, 2015 to March 21, 2016. Variations of different nitrogen forms in the soil were analyzed under different culture conditions. The results showed that mean content of total nitrogen was 1403.7 mg/kg. In the end of the experiment, mean contents of total nitrogen in the soil under constant dry, constant humidity, dry and wet alternation, raising of water level, and decline of the water level treatments without Carex cinerascens were 1413.3 mg/kg, 1358.0 mg/kg, 1325.0 mg/kg, 1414.7 mg/kg and 1446.0 mg/kg. Mean contents of total nitrogen in the soil under dry and wet alternation, raising of water level, and decline of the water level treatments were 1612.3 mg/kg, 1329.3 mg/kg and 1395.7 mg/kg.The contents of total nitrogen under constant humidity and dry and wet alternation treatments decreased by 10.9%. Under the constant humidity treatment, the content of ammonium nitrogen increased at the depth of 0-2 cm, and reached 24.8 mg/kg at the end of culture. The total nitrogen, ammonia nitrogen and nitrate nitrogen in the soil increased with the decomposition of Carex cinerascens in the 2-5 cm soil, but the contents of the 0-2 cm soil in the adding Carex cinerascens treatment were less than unsupplemented groups. Under different culture treatments, variation of soil nitrogen under the constant humidity and dry and wet alternation treatments was the most obvious, and the abundance of carbon sources provided by the decomposition of Carex cinerascens increased microbial activity.