scholarly journals Effects of snow absence on N pools and enzyme activities within soil aggregates in a spruce forest on the eastern Tibetan Plateau

2021 ◽  
Author(s):  
Zhijie Li ◽  
Zimin Li ◽  
Rüdiger Reichel ◽  
Kaijun Yang ◽  
Li Zhang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Snow Cover ◽  
Enzyme Activities ◽  
N Mineralization ◽  
Soil Aggregates ◽  
Net N Mineralization ◽  
Spruce Forest ◽  
Soil N ◽  
Eastern Tibetan Plateau ◽  
Inorganic N

Abstract Background Snow cover change has a great potential to impact soil nitrogen (N) pools and enzyme activities in boreal forests. Yet, the nature of this biochemical processes within soil aggregates is still limited. We conducted a snow manipulation experiment to investigate the effects of snow absence on N pools and enzyme activities within soil aggregates in a subalpine spruce forest on the eastern Tibetan Plateau of China. Results Snow absence increased extractable inorganic N pools (ammonium and nitrate) and enzyme activities, accompanying with the improvement of N mineralization rate. Regardless of snow manipulations, both soil extractable inorganic N and net N mineralization was higher in macroaggregates than that in the other two aggregates. In contrast, microaggregates had higher urease and nitrite reductase activities compared to macroaggregates and large macroaggregates. Compared with small macroaggregates and large macroaggregates, N pools and enzymes within microaggregates is more sensitive to snow absence. Conclusions Our results indicated that the impacts of snow cover change on soil N dynamic depend on aggregate sizes and winter conditions (e.g., snow cover and temperature). Such findings have important implication for soil N cycling in snow-covered subalpine forests experiencing pronounced winter climate change.

scholarly journals Inorganic Nitrogen Production and Removal along the Sediment Gradient of a Stormwater Infiltration Basin

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 320
Author(s):  
Qianyao Si ◽  
Mary G. Lusk ◽  
Patrick W. Inglett
Keyword(s):  
Removal Efficiency ◽  
N Mineralization ◽  
Inorganic Nitrogen ◽  
Dry Season ◽  
Pollutant Removal ◽  
Net N Mineralization ◽  
Wet Season ◽  
Inorganic N ◽  
N Removal ◽  
Stormwater Infiltration

Stormwater infiltration basins (SIBs) are vegetated depressions that collect stormwater and allow it to infiltrate to underlying groundwater. Their pollutant removal efficiency is affected by the properties of the soils in which they are constructed. We assessed the soil nitrogen (N) cycle processes that produce and remove inorganic N in two urban SIBs, with the goal of further understanding the mechanisms that control N removal efficiency. We measured net N mineralization, nitrification, and potential denitrification in wet and dry seasons along a sedimentation gradient in two SIBs in the subtropical Tampa, Florida urban area. Net N mineralization was higher in the wet season than in the dry season; however, nitrification was higher in the dry season, providing a pool of highly mobile nitrate that would be susceptible to leaching during periodic dry season storms or with the onset of the following wet season. Denitrification decreased along the sediment gradient from the runoff inlet zone (up to 5.2 μg N/g h) to the outermost zone (up to 3.5 μg N/g h), providing significant spatial variation in inorganic N removal for the SIBs. Sediment accumulating around the inflow areas likely provided a carbon source, as well as maintained stable anaerobic conditions, which would enhance N removal.

Empirical relationships between temperature and nitrogen availability across North American forests

1992 ◽  
Vol 22 (5) ◽  
pp. 707-712 ◽  
Author(s):  
Xiwei Yin
Keyword(s):  
N Mineralization ◽  
Regional Scale ◽  
Mineral Soil ◽  
Published Data ◽  
N Availability ◽  
Net N Mineralization ◽  
Soil N ◽  
Litter Fall ◽  
Available N ◽  
N Pool

Published data were analyzed to examine whether nitrogen (N) availability varies along macroclimatic gradients in North America. Extractable N produced during 8-week aerobic laboratory incubation was used as an index of potential net N mineralization. Mean extractable N during the growing season in the forest floor plus top mineral soil was used as an index of the available N pool. Using multiple regression, potential net N mineralization was shown to increase with available N and with litter-fall N (R2 = 0.722). Available N increased with increasing total soil N and with decreasing mean January and July air temperatures (R2 = 0.770). These relationships appeared to hold also for deciduous and coniferous forests separately across regions. Results suggest that net N mineralization output under uniform temperature and moisture conditions can be generally expressed by variations of N input (litter fall) and the available soil N pool, and that the available soil N pool is predictable along a temperature gradient at a regional scale.

scholarly journals Nitrogen Availability and Uptake by Sugarbeet in Years Following a Manure Application

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Rodrick D. Lentz ◽  
Gary A. Lehrsch
Keyword(s):  
N Mineralization ◽  
Dairy Manure ◽  
High Rate ◽  
N Availability ◽  
Net N Mineralization ◽  
Soil N ◽  
Manure Application ◽  
Total N ◽  
Urea Fertilizer ◽  
Low Rate

The use of solid dairy manure for sugarbeet production is problematic because beet yield and quality are sensitive to deficiencies or excesses in soil N, and soil N availability from manure varies substantially depending on the year of application. Experimental treatments included combinations of two manure rates (0.33 and 0.97 Mg total N ha−1) and three application times, and non-manure treatments (control and urea fertilizer). We measured soil net N mineralization and biomass, N uptake, and yields for sprinkler-irrigated sugarbeet. On average, the 1-year-old, low-rate manure, and 1- and 2-year-old, high-rate manure treatments produced 1.2-fold greater yields, 1.1-fold greater estimated recoverable sugar, and 1.5-fold greater gross margins than that of fertilizer alone. As a group the 1-year-old, low-rate manure, and 2- and 3-year-old, high-rate-manure treatments produced similar cumulative net N mineralization as urea fertilizer; whereas the 1-year-old, high-rate manure treatment provided nearly 1.5-fold more N than either group. With appropriate manure application rates and attention to residual N and timing of sugarbeet planting, growers can best exploit the N mineralized from manure, while simultaneously maximizing sugar yields and profits.

scholarly journals The simulated N deposition accelerates net N mineralization and nitrification in a tropical forest soil

2019 ◽  
Vol 16 (21) ◽  
pp. 4277-4291
Author(s):  
Yanxia Nie ◽  
Xiaoge Han ◽  
Jie Chen ◽  
Mengcen Wang ◽  
Weijun Shen
Keyword(s):  
N Deposition ◽  
Functional Genes ◽  
Net N Mineralization ◽  
Soil N ◽  
Wet Season ◽  
Inorganic N ◽  
N Transformations ◽  
N Transformation ◽  
Soil N Transformation ◽  
N Additions

Abstract. Elevated nitrogen (N) deposition affects soil N transformations in the N-rich soil of tropical forests. However, the change in soil functional microorganisms responsible for soil N cycling remains largely unknown. Here, we investigated the variation in soil inorganic N content, net N mineralization (Rm), net nitrification (Rn), inorganic N leaching (Rl), N2O efflux and N-related functional gene abundance in a tropical forest soil over a 2-year period with four levels of N addition. The responses of soil net N transformations (in situ Rm and Rn) and Rl to N additions were negligible during the first year of N inputs. The Rm, Rn, and Rl increased with the medium nitrogen (MN) and high nitrogen (HN) treatments relative to the control treatments in the second year of N additions. Furthermore, the Rm, Rn, and Rl were higher in the wet season than in the dry season. The Rm and Rn were mainly associated with the N addition-induced lower C:N ratio in the dry season but with higher microbial biomass in the wet season. Throughout the study period, high N additions increased the annual N2O emissions by 78 %. Overall, N additions significantly facilitated Rm, Rn, Rl and N2O emission. In addition, the MN and HN treatments increased the ammonia-oxidizing archaea (AOA) abundance by 17.3 % and 7.5 %, respectively. Meanwhile, the HN addition significantly increased the abundance of nirK denitrifiers but significantly decreased the abundance of ammonia-oxidizing bacteria (AOB) and nosZ-containing N2O reducers. To some extent, the variation in functional gene abundance was related to the corresponding N-transformation processes. Partial least squares path modelling (PLS-PM) indicated that inorganic N contents had significantly negative direct effects on the abundances of N-related functional genes in the wet season, implying that chronic N deposition would have a negative effect on the N-cycling-related microbes and the function of N transformation. Our results provide evidence that elevated N deposition may impose consistent stimulatory effects on soil N-transformation rates but differentiated impacts on related microbial functional genes. Long-term experimentation or observations are needed to decipher the interrelations between the rate of soil N-transformation processes and the abundance or expression of related functional genes.

Relationships between soil nitrogen dynamics and natural 15N abundance in plant foliage from Great Smoky Mountains National Park

1994 ◽  
Vol 24 (8) ◽  
pp. 1636-1645 ◽  
Author(s):  
Charles T. Garten Jr. ◽  
Helga Van Miegroet
Keyword(s):  
N Mineralization ◽  
Enrichment Factors ◽  
High Elevation ◽  
N Availability ◽  
Net N Mineralization ◽  
Soil N ◽  
N Dynamics ◽  
Great Smoky Mountains ◽  
Soil N Dynamics ◽  
Mineral Soils

We tested the hypothesis that naturally occurring nitrogen (N) isotope ratios in foliage (from plants that do not symbiotically fix atmospheric N2) are an indicator of soil N dynamics in forests. Replicate plots were established at eight locations ranging in elevation from 615 to 1670 m in Great Smoky Mountains National Park in eastern Tennessee, U.S.A. The locations selected ranged from N-poor (low-elevation) to N-rich (high-elevation) forest stands. Soils were sampled in June 1992; plants, forest floors, and upper mineral soils were sampled in August 1992. Net N mineralization and net nitrification potentials for surface mineral soils and organic matter layers at each site were determined by aerobic laboratory incubations. Soils and organic layers from high-elevation sites had greater net N mineralization and nitrification potentials than soils from low-elevation sites. There were significant (P ≤ 0.05) differences between study sites in soil 15N abundance. Therefore, we examined correlations between measures of soil N availability and both mean foliar δ15N values and mean enrichment factors (εp−s = δ15Nleaf − δ15Nsoil). In evergreens, maples, and ferns, mean foliar δ15N values and mean enrichment factors were positively correlated with net N mineralization and net nitrification potentials in soil. The observed relationships between natural 15N abundance in plant leaves and soil N availability were explained by a simple model of soil N dynamics. The model predicts how the isotopic composition of plant N is affected by the following factors: (i) varying uptake of soil NH4-N and NO3-N, (ii) the isotopic composition of different soil N pools, and (iii) relative rates of soil N transformations.

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