红壤水稻土微生物生物量氮与总氮矿化的关系

通过田间采样并布置室内培育试验,研究了红壤水稻土微生物生物量N和总N的矿化动态及其相互关系。结果表明,红壤水稻土微生物生物量N矿化速率和矿化量随培养时间延长而降低,随水稻土肥力水平提高而增加。12周培养期内,红壤水稻土微生物生物量N的一半以上被矿化,其中约1/2的矿化量出现在前4周;不同熟化程度红壤水稻土的累积矿化N量为73.0～127.8mg/kg,平均矿化速率为6.09～10.7mg/(kg·wk)。用双指数方程和一级动力学方程可以很好地模拟红壤水稻土微生物生物量N和总N的矿化过程。微生物生物量N和总N的矿化过程均可分为快速和缓慢2个阶段,培养的前8周是快速矿化阶段。2个模拟方程参数的比较表明,微生物生物量N矿化量占总N矿化量的比例为10.8%～49.5%,其矿化潜力大,持续矿化时间长,对保证土壤N素的持续供应有积极作用。

Relationship between microbial biomass N mineralization and total nitrogen mineralization in paddy soils of subtropical China

The relationship between microbial biomass N and total N mineralization dynamics in paddy soils of subtropical China was investigated by lab incubation experiment. Results showed that the amount and rate of soil microbial biomass N mineralization decreased with the incubation time but increased with the promotion of soil fertility. During 12 weeks incubation, more than half of microbial biomass N was mineralized, in which half was occurred in the first 4 weeks. The cumulative N mineralization in paddy soils ranged from 73.0 to 127.8 mg/kg, and the rates ranged from 6.09 to 10.7 mg/(kg·wk). Two component equation and dynamic equation could simulate microbial biomass N and total N mineralization, respectively. Both the microbial biomass N and total N mineralization processes could be divided into two periods: rapid mineralization period in the first 8 weeks and thereafter slow mineralization period. The comparison between parameters in two equations showed that the proportion of microbial biomass N mineralization in soil total N mineralization varied from 10.8% to 49.5%. Microbial biomass N has a large mineralization potential and continuously-rapid turnover capacity. It plays an important role in maintaining soil nitrogen supply.