Effects of Freezing-Thawing Processes on Net Nitrogen Mineralization in Salinized Farmland Soil
AGRONOMY-BASEL(2022)
摘要
Nitrogen is an indispensable and limiting element for plant and microbial growth. To investigate the combined effects of salinity and freezing-thawing (FT) processes on soil inorganic nitrogen (SIN) transformation in seasonally freezing salinized farmland, laboratory incubation experiments were conducted under five soil salt content (SSC) treatments (0.08%, 0.25%, 0.35%, 0.50%, and 0.70%), four FT temperature treatments (C (5 degrees C), FT (-5 + 5 degrees C), FT (-10 + 5 degrees C), and FT (-15 + 5 degrees C)), and two soil water content (SWC) treatments (40% and 80% of maximum water holding capacity (WHC)). Ammonium (NH4+-N) and nitrate (NO3--N) nitrogen were monitored at the first, second, fifth, and eighth incubation days. The FT processes increased relative NH4+-N content by 13%, 39%, and 77% with the decreasing of freezing temperature from -5 degrees C to -15 degrees C compared with C (5 degrees C) treatments, respectively. FT (-5 + 5 degrees C) and FT (-15 + 5 degrees C) treatments decreased the relative NO3--N contents by 4% and 6% compared with C (5 degrees C) treatments, respectively. Under FT treatments, the increment of relative NH4+-N content was higher in low-SSC treatments and lower in high-SSC treatments. The relationship between relative NO3--N content and SSC gradually changed from a decrease in C (5 degrees C) to an increase in FT (-15+5 degrees C) treatments. SWC decreased NH4+-N content in high-SSC and low-freezing temperature treatments (SSC x freezing temperature < -2.5%center dot degrees C), while NH4+-N increased in low-SSC and unfrozen treatments. The variations of SIN/R-min (nitrogen mineralization rate) were mostly affected by NO3--N/R-nit (net nitrification rate) and NH4+-N/Ra (net ammonification rate) in C (5 degrees C) and FT treatments, respectively. Overall, the results suggested that enhanced salinity inhibited the effects of freezing temperature on NH4+-N and NO3--N formation, respectively. The increase in SWC weakened the NH4+-N formation induced by the decrease in freezing temperature, and this function increased with the increase in salinity.
更多查看译文
关键词
ammonium nitrogen,nitrate nitrogen,salinity,soil water content
AI 理解论文
溯源树
样例
![](https://originalfileserver.aminer.cn/sys/aminer/pubs/mrt_preview.jpeg)
生成溯源树,研究论文发展脉络
Chat Paper
正在生成论文摘要