Effects of Temperature and Humidity on Soil Gross Nitrogen Transformation in a Typical Shrub Ecosystem in Yanshan Mountain and Hilly Region

Abstract

Shrubland is a pivotal terrestrial ecosystem in China. Soil nitrogen transformations play a crucial role in maintaining the productivity of this ecosystem, yet the driving forces underlying it have not been sufficiently addressed, particularly under ongoing climate changes. Herein, by incorporating 15N isotope pool dilution method in laboratory incubation, the rates of gross N ammonification, nitrification, and inorganic N consumption in soils in response to varying temperature and humidity conditions were determined at different depths (SL10: 0–10 cm, and SL20: 10–20 cm) in a typical shrub ecosystem in the Yanshan mountain and hilly region, North China. The gross rates of ammonification and nitrification of soils in SL10 were higher than those in SL20, which was likely affected by the higher soil organic matter and total N contents at a shallower depth. Both temperature and humidity significantly affected the N transformations. The gross ammonification and nitrification were significantly stimulated as the incubation temperature increased from 5 to 35 °C. The gross ammonification increased exponentially, while the gross nitrification increased differently in different temperature ranges. The increment of soil water contents (from 30% WHC to 60% and 100% WHC) promoted the gross nitrification rate more significantly than the gross ammonification rate. The gross nitrification ceased until soil water content reached 60%WHC, indicating that soil water availability between 60% and 100% WHC was not a limiting factor in the nitrification process for the shrubland soils in this study. The ammonium (NH4+) immobilization was significantly lower than nitrification irrespective of varying environmental conditions, even though the NH4+ consumption rate might be overestimated, uncovering two putative processes: (1) heterotrophic nitrification process; (2) and more competitive nitrifying bacteria than NH4+-immobilizing microorganisms. Our study is indispensable for assessing the stability and sustainability of soil N cycling in the shrub ecosystem under climate changes.

The Importance of the Mineral Substrate of the Biofilm in the Process of Low-Temperature Removal of Nitrogen Compounds from Wastewater

“…Research shows that lowering sewage temperatures helps reduce the number of bacteria and archaea. Similar dependencies were obtained for soil, where humidity and temperature affect the rate of ammonification and nitrification [9,10]. Previous research indicates that ammonia-oxidizing bacteria (AOB) dominate in the soil at low temperatures, and ammonia-oxidizing archaea (AOA) dominate at high temperatures [11].…”

“…Mechanically pre-treated sewage gravitationally flows through the separation chamber to the averaging tank (3) from where it is pumped further to two biological reactors of the SBR type (4.1) and (4.2). The phases of reactor operation, aerobic and anaerobic conditions, and filling and decanting of sewage are shown later in the workBiological phosphorus removal is supported using a PIX coagulant dosed into SBR reactors from the PIX dosing station (9). In addition, sludge management is conducted.…”

Unveiling Environmental Influences on Sustainable Fertilizer Production through Insect Farming

“…Previous studies by MacDonald et al [36] also found that the rate of microbial respiration and the mineralization of nitrogen waste degradation are temperature-dependent. In Hu et al [37], it is further highlighted how moisture variation impacts microbial activities, oxygen concentration, and nutrient transport. Excessive moisture potentially leads to nitrogen loss via denitrification and impeding BSF larval growth.…”

Warming Mitigates the Impacts of Degradation on Nitrogen Allocation between Soil Microbes and Plants in Alpine Meadow

“…This makes the impact of climate warming more pronounced in these areas. Research has determined that temperature and humidity are key factors influencing the mineralization of different types of soil N [37,38], with temperature playing a more prominent role [39]. In general, an increase in soil temperature facilitates the N cycle in the soil [40,41], while a reduction in soil moisture content impedes this process [42].…”