不同温湿度条件下杨树人工林土壤氮矿化特征研究

为了掌握不同温度和湿度条件下杨树人工林土壤的氮矿化过程,探明土壤在干旱条件下的氮矿化特征,采用室内培养法,将含水量分别为田间持水量的20%(重度干旱处理)、40%(轻度干旱处理)和70%(对照处理)的杨树人工林表层土壤(0~10 cm),分别置于15、20、25、30℃恒温条件下进行了8周培养试验,研究不同温湿度条件下的土壤氮矿化特征。结果表明:(1)土壤净氮矿化量与温度呈极显著正相关关系(P0.01);(2)在较低温度条件下(15、20℃),不同湿度土壤净氮矿化量表现为轻度干旱重度干旱对照,而在较高温度条件下(25、30℃),培养前期的氮矿化量变化规律与低温处理一致,但至培养后期,则表现为对照轻度干旱重度干旱;(3)各种处理土壤矿质氮主要以硝态氮为主;(4)土壤电导率与土壤硝态氮含量、净氮矿化量呈极显著正相关关系(P0.01)。研究表明适度干旱能够促进土壤氮的早期矿化,但适宜的湿度更有利于土壤氮的长期矿化。

Study on the Effects of Temperature and Moisture on Nitrogen Mineralization of Soil in Poplar Plantations

In order to understand the nitrogen mineralization characteristics of poplar plantation soil in different temperature and moisture conditions, especially under drought condition, the author used laboratory incubation method, incubated poplar plantation topsoil from 0-10 cm layer of three soil moisture 20% (severe drought), 40% (mild drought) and 70% (control) of field moisture capacity for 8 weeks at 15, 20, 25 and , respectively. The results showed that:(1) the net nitrogen mineralization accumulation of soil was positively related to temperature (P<0.01); (2) at 15 and , the net nitrogen mineralization accumulation of soil in different moisture showed the order of mild drought>severe drought>control treatment; at 25 and , the sequence was the same as that at 15 and in early incubation, while the order was control>mild drought>severe drought in the subsequent incubation time; (3) the net nitrogen mineralization accumulation was mainly nitrate nitrogen in the soil; (4) soil electrical conductivity was significantly positively related to soil nitrate nitrogen and net nitrogen mineralization accumulation (P<0.01). It was suggested that slight drought condition was conducive to soil nitrogen mineralization in the early incubation period, however, the appropriate moisture condition could promote soil nitrogen mineralization in the long-term incubation period.