Heterogeneity in soil nitrogen within first-order forested catchments at the Turkey Lakes Watershed

2005 ◽  
Vol 35 (4) ◽  
pp. 797-805 ◽  
Author(s):  
Neil Foster ◽  
John Spoelstra ◽  
Paul Hazlett ◽  
Sherry Schiff ◽  
Frederick Beall ◽  
...  
Keyword(s):  
Soil Water ◽  
Organic N ◽  
Net N Mineralization ◽  
Forested Catchments ◽  
N Dynamics ◽  
Turkey Lakes Watershed ◽  
Topographic Positions ◽  
Lower Slope ◽  
Isotopic Effects

Topographic positional regulation of nitrogen (N) dynamics in soil within Canadian Shield headwaters, located in calibrated catchments containing mature, tolerant hardwood forest, was examined to determine how N pools, mineralization, nitrification, and leaching in soil relate to N export in drainage waters. A uniformly high net N mineralization and nitrification potential for surficial soil layers rich in organic N was demonstrated for ridge, upper-middle slope, and lower slope – footslope topographic positions. Results from plot-scale studies revealed that NO3– concentrations in soil water from well-drained soils were very highly variable throughout the catchments, ranging from 25 to 175 µmol·L–1, with a median of 80 µmol·L–1. The isotopic effects of denitrification were not detected in soil water collected from lower slope – footslopes, and in situ rates of N2O production from soils on lower slope – footslopes and valley bottoms were very low and highly variable. Higher N exports from soils than from streams were not explained by differences in soil water N with topographic position or denitrification in lower landscape topographic positions. Using an average soil water N value, based on the replicated plots within catchments, did not reduce the calculated substantial differences in N export between soils and streams.

Soil resources and the growth and nutrition of tree seedlings near harvest gap – forest edges in interior cedar–hemlock forests of British Columbia

2006 ◽  
Vol 36 (1) ◽  
pp. 62-76 ◽  
Author(s):  
Michael B Walters ◽  
Cleo C Lajzerowicz ◽  
K David Coates
Keyword(s):  
Soil Water ◽  
Seedling Growth ◽  
N Mineralization ◽  
Forest Edge ◽  
Organic N ◽  
Tree Seedlings ◽  
Net N Mineralization ◽  
Soil N ◽  
Forest Edges ◽  
Mineral N

Observations of tree seedlings with chlorotic foliage and stunted growth near harvest gap – forest edges in interior cedar–hemlock forests inspired a study addressing the following questions: (1) Do seedling foliar chemistry, foliar nitrogen (N) versus growth relationships, and fertilizer responses suggest N-limited seedling growth? (2) Are patterns in soil characteristics consistent with N limitation, and can interrelationships among these characteristics infer causality? Our results suggest that seedling growth near gap–forest edges was colimited by N and light availability. Soil mineral N and dissolved organic N (DON) concentrations, in situ net N mineralization, and water generally increased from forest to gap, whereas N mineralization from a laboratory incubation and total N and carbon did not vary with gap–forest position. Interrelations among variables and path analysis suggest that soil water and total soil N positively affect DON concentration and N mineralization, and proximity to mature gap–forest edge trees negatively impacts mineral N concentration and water. Collectively, our results suggest that soil N levels which limit seedling growth near gap edges can be partially explained by the direct negative impacts of gap–forest edge trees on mineral N concentrations and their indirect impacts on N cycling via soil water, and not via effects on substrate chemistry.

scholarly journals Temporal and spatial variation of nitrogen transformations in nitrogen-saturated soils of a central Appalachian hardwood forest

2001 ◽  
Vol 31 (10) ◽  
pp. 1768-1785 ◽  
Author(s):  
Frank S Gilliam ◽  
Bradley M Yurish ◽  
Mary Beth Adams
Keyword(s):  
Soil Moisture ◽  
Spatial Variability ◽  
Soil Water ◽  
Spatial Patterns ◽  
N Saturation ◽  
Net N Mineralization ◽  
Nitrogen Transformations ◽  
N Dynamics ◽  
Temporal And Spatial ◽  
Nitrogen Additions

We studied temporal and spatial patterns of soil nitrogen (N) dynamics from 1993 to 1995 in three watersheds of Fernow Experimental Forest, W.V.: WS7 (24-year-old, untreated); WS4 (mature, untreated); and WS3 (24-year-old, treated with (NH4)2SO4 since 1989 at the rate of 35 kg N·ha–1·year–1). Net nitrification was 141, 114, and 115 kg N·ha–1·year–1, for WS3, WS4, and WS7, respectively, essentially 100% of net N mineralization for all watersheds. Temporal (seasonal) patterns of nitrification were significantly related to soil moisture and ambient temperature in untreated watersheds only. Spatial patterns of soil water NO3– of WS4 suggest that microenvironmental variability limits rates of N processing in some areas of this N-saturated watershed, in part by ericaceous species in the herbaceous layer. Spatial patterns of soil water NO3– in treated WS3 suggest that later stages of N saturation may result in higher concentrations with less spatial variability. Spatial variability in soil N variables was lower in treated WS3 versus untreated watersheds. Nitrogen additions have altered the response of N-processing microbes to environmental factors, becoming less sensitive to seasonal changes in soil moisture and temperature. Biotic processes responsible for regulating N dynamics may be compromised in N-saturated forest ecosystems.

Modelling stream and soil water nitrate dynamics during experimentally increased nitrogen deposition in a coniferous forest catchment at Gårdsjön, Sweden

2009 ◽  
Vol 40 (2-3) ◽  
pp. 187-197
Author(s):  
M. N. Futter ◽  
R. A. Skeffington ◽  
P. G. Whitehead ◽  
F. Moldan
Keyword(s):  
Soil Water ◽  
Stream Water ◽  
Inorganic Nitrogen ◽  
Coniferous Forest ◽  
Water Dynamics ◽  
N Leaching ◽  
N Addition ◽  
Catchment Scale ◽  
Forested Catchments ◽  
N Dynamics

Increased atmospheric deposition of inorganic nitrogen (N) may lead to increased leaching of nitrate (NO3−) to surface waters. The mechanisms responsible for, and controls on, this leaching are matters of debate. An experimental N addition has been conducted at Gårdsjön, Sweden to determine the magnitude and identify the mechanisms of N leaching from forested catchments within the EU funded project NITREX. The ability of INCA-N, a simple process-based model of catchment N dynamics, to simulate catchment-scale inorganic N dynamics in soil and stream water during the course of the experimental addition is evaluated. Simulations were performed for 1990–2002. Experimental N addition began in 1991. INCA-N was able to successfully reproduce stream and soil water dynamics before and during the experiment. While INCA-N did not correctly simulate the lag between the start of N addition and NO3− breakthrough, the model was able to simulate the state change resulting from increased N deposition. Sensitivity analysis showed that model behaviour was controlled primarily by parameters related to hydrology and vegetation dynamics and secondarily by in-soil processes.

scholarly journals Nitrogen fertilizer value of animal slurries with different proportions of liquid and solid fractions: A 3-year study under field conditions

2021 ◽  
pp. 1-11
Author(s):  
Betina Nørgaard Pedersen ◽  
Bent T. Christensen ◽  
Luca Bechini ◽  
Daniele Cavalli ◽  
Jørgen Eriksen ◽  
...  
Keyword(s):  
Solid Fraction ◽  
Liquid Fraction ◽  
N Fertilizer ◽  
Organic N ◽  
First Year ◽  
Net N Mineralization ◽  
Pig Slurry ◽  
Total N ◽  
Plant Availability ◽  
Loamy Sand Soil

Abstract The plant availability of manure nitrogen (N) is influenced by manure composition in the year of application whereas some studies indicate that the legacy effect in following years is independent of the composition. The plant availability of N in pig and cattle slurries with variable contents of particulate matter was determined in a 3-year field study. We separated cattle and a pig slurry into liquid and solid fractions by centrifugation. Slurry mixtures with varying proportions of solid and liquid fraction were applied to a loamy sand soil at similar NH4+-N rates in the first year. Yields and N offtake of spring barley and undersown perennial ryegrass were compared to plots receiving mineral N fertilizer. The first year N fertilizer replacement value (NFRV) of total N in slurry mixtures decreased with increasing proportion of solid fraction. The second and third season NFRV averaged 6.5% and 3.8% of total N, respectively, for cattle slurries, and 18% and 7.5% for pig slurries and was not related to the proportion of solid fraction. The estimated net N mineralization of residual organic N increased nearly linearly with growing degree days (GDD) with a rate of 0.0058%/GDD for cattle and 0.0116%/GDD for pig slurries at 2000–5000 GDD after application. In conclusion NFRV of slurry decreased with increasing proportion of solid fraction in the first year. In the second year, NFRV of pig slurry N was significantly higher than that of cattle slurry N and unaffected by proportion between solid and liquid fraction.

scholarly journals Effects of experimental freezing on soil nitrogen dynamics in soils from a net nitrification gradient in a nitrogen-saturated hardwood forest ecosystem

2010 ◽  
Vol 40 (3) ◽  
pp. 436-444 ◽  
Author(s):  
Frank S. Gilliam ◽  
Adam Cook ◽  
Salina Lyter
Keyword(s):  
N Mineralization ◽  
Soil Freezing ◽  
N Saturation ◽  
Net N Mineralization ◽  
N Dynamics ◽  
Net Nitrification ◽  
Soil Nitrogen Dynamics ◽  
Soil N Cycle ◽  
N Mineralization Potential ◽  
Fernow Experimental Forest

This study examined effects of soil freezing on N dynamics in soil along an N processing gradient within a mixed hardwood dominated watershed at Fernow Experimental Forest, West Virginia. Sites were designated as LN (low rates of N processing), ML (moderately low), MH (moderately high), and HN (high). Soils underwent three 7-day freezing treatments (0, –20, or –80 °C) in the laboratory. Responses varied between temperature treatments and along the gradient. Initial effects differed among freezing treatments for net N mineralization, but not nitrification, in soils across the gradient, generally maintained at LN < ML ≤ MH < HN for all treatments. Net N mineralization potential was higher following freezing at –20 and –80 °C than control; all were higher than at 0 °C. Net nitrification potential exhibited similar patterns. LN was an exception, with net nitrification low regardless of treatment. Freezing response of N mineralization differed greatly from that of nitrification, suggesting that soil freezing may decouple two processes of the soil N cycle that are otherwise tightly linked at our site. Results also suggest that soil freezing at temperatures commonly experienced at this site can further increase net nitrification in soils already exhibiting high nitrification from N saturation.

In situ arsenic speciation at the soil/water interface of saline-alkaline lakes of the Pantanal, Brazil: A DGT-based approach

2021 ◽  
pp. 150113
Author(s):  
José Lucas Martins Viana ◽  
Adriana Felix de Souza ◽  
Amauris Hechavarría Hernández ◽  
Lucas Pellegrini Elias ◽  
Carlos Eduardo Eismann ◽  
...  
Keyword(s):  
Soil Water ◽  
Arsenic Speciation ◽  
Water Interface ◽  
Alkaline Lakes

scholarly journals From near-surface to root-zone soil moisture using an exponential filter: an assessment of the method based on in-situ observations and model simulations

2008 ◽  
Vol 12 (6) ◽  
pp. 1323-1337 ◽  
Author(s):  
C. Albergel ◽  
C. Rüdiger ◽  
T. Pellarin ◽  
J.-C. Calvet ◽  
N. Fritz ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Surface Soil ◽  
Root Zone ◽  
Synthetic Data ◽  
Surface Soil Moisture ◽  
Data Set ◽  
Water Index ◽  
In Situ Observations

Abstract. A long term data acquisition effort of profile soil moisture is under way in southwestern France at 13 automated weather stations. This ground network was developed in order to validate remote sensing and model soil moisture estimates. In this paper, both those in situ observations and a synthetic data set covering continental France are used to test a simple method to retrieve root zone soil moisture from a time series of surface soil moisture information. A recursive exponential filter equation using a time constant, T, is used to compute a soil water index. The Nash and Sutcliff coefficient is used as a criterion to optimise the T parameter for each ground station and for each model pixel of the synthetic data set. In general, the soil water indices derived from the surface soil moisture observations and simulations agree well with the reference root-zone soil moisture. Overall, the results show the potential of the exponential filter equation and of its recursive formulation to derive a soil water index from surface soil moisture estimates. This paper further investigates the correlation of the time scale parameter T with soil properties and climate conditions. While no significant relationship could be determined between T and the main soil properties (clay and sand fractions, bulk density and organic matter content), the modelled spatial variability and the observed inter-annual variability of T suggest that a weak climate effect may exist.

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