Effects of chronic nitrogen additions on nitrogen cycling in a high-elevation spruce–fir stand

1993 ◽  
Vol 23 (7) ◽  
pp. 1252-1263 ◽  
Author(s):  
S.G. McNulty ◽  
J.D. Aber
Keyword(s):  
N Mineralization ◽  
Forest Floor ◽  
Basal Area ◽  
Ion Exchange Resin ◽  
High Elevation ◽  
N Fertilization ◽  
First Year ◽  
Net N Mineralization ◽  
Living Dead ◽  
A Site

A 3-year low-level (15–31 kg N•ha−1•year−1) fertilization treatment was conducted in a high-elevation spruce–fir stand, on Mount Ascutney, Vermont. Shortly after fertilization, large concentrations (≤ 900 ppm) of both NH4-N and NO3-N were recovered in ion-exchange resin bags buried at the base of the forest floor. Despite an initial loss of added N, we found significant correlations between the amount of fertilizer applied and measured ecosystem parameters. Bulk deposition for the plots equalled 5.1 kg N•ha−1•year−1, of which 50% fell as NO3-N in snow. No correlations were found between the amount of N applied to a site and throughfall N concentration of the site. Increased Basal Area (BA) growth was recorded using two separate techniques, with the greatest increases in living BA occurring on the 25.6 kg N•ha−1year−1 treatment. As N fertilization increased, foliar %N, net forest floor net N mineralization, dead BA, total (living + dead) BA, first year net N mineralization, and coniferous and deciduous litter %N also increased. On plots receiving high rates of fertilization, net N mineralization rates remained constant or decreased during the third year while low N addition plots experienced increased net N mineralization rates, suggesting a possible C limitation. These results indicate that these slow growing, nutrient conserving ecosystems are responsive to even small increases in N inputs.

scholarly journals Incubation methods for assessing mineralizable nitrogen in soils under sugarcane

2013 ◽  
Vol 37 (2) ◽  
pp. 450-461 ◽  
Author(s):  
Eduardo Mariano ◽  
Paulo Cesar Ocheuze Trivelin ◽  
José Marcos Leite ◽  
Michele Xavier Vieira Megda ◽  
Rafael Otto ◽  
...  
Keyword(s):  
N Mineralization ◽  
Standard Technique ◽  
Extraction Methods ◽  
N Fertilization ◽  
Chemical Extraction ◽  
Net N Mineralization ◽  
Anaerobic Incubation ◽  
Aerobic Incubation ◽  
Mineralizable N

Considering nitrogen mineralization (N) of soil organic matter is a key aspect for the efficient management of N fertilizers in agricultural systems. Long-term aerobic incubation is the standard technique for calibrating the chemical extraction methods used to estimate the potentially mineralizable N in soil. However, the technique is laborious, expensive and time-consuming. In this context, the aims of this study were to determine the amount of soil mineralizable N in the 0-60 cm layer and to evaluate the use of short-term anaerobic incubation instead of long-term aerobic incubation for the estimation of net N mineralization rates in soils under sugarcane. Five soils from areas without previous N fertilization were used in the layers 0-20, 20-40 and 40-60 cm. Soil samples were aerobically incubated at 35 ºC for 32 weeks or anaerobically incubated (waterlogged) at 40 ºC for seven days to determine the net soil N mineralization. The sand, silt and clay contents were highly correlated with the indexes used for predicting mineralizable N. The 0-40 cm layer was the best sampling depth for the estimation of soil mineralizable N, while in the 40-60 cm layer net N mineralization was low in both incubation procedures. Anaerobic incubation provided reliable estimates of mineralizable N in the soil that correlated well with the indexes obtained using aerobic incubation. The inclusion of the pre-existing NH4+-N content improved the reliability of the estimate of mineralizable N obtained using anaerobic incubation.

scholarly journals Mid-Term Effects of Forest Thinning on N Mineralization in a Semi-Arid Aleppo Pine Forest

Forests ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1470
Author(s):  
Inmaculada Bautista ◽  
Luis Lado-Monserrat ◽  
Cristina Lull ◽  
Antonio Lidón
Keyword(s):  
N Mineralization ◽  
Nutrient Dynamics ◽  
Pinus Halepensis ◽  
Block Design ◽  
Plant Cover ◽  
Basal Area ◽  
Net N Mineralization ◽  
Mineral N ◽  
Silvicultural Treatments ◽  
Randomized Block Design

In order to assess the sustainability of silvicultural treatments in semiarid forests, it is necessary to know how they affect the nutrient dynamics in the forest. The objective of this paper is to study the effects of silvicultural treatments on the net N mineralization and the available mineral N content in the soil after 13 years following forest clearings. The treatments were carried out following a randomized block design, with four treatments and two blocks. The distance between the two blocks was less than 3 km; they were located in Chelva (CH) and Tuéjar (TU) in Valencia, Spain. Within each block, four experimental clearing treatments were carried out in 1998: T0 control; and T60, T75 and T100 where 60%, 75% and 100 of basal area was eliminated, respectively. Nitrogen dynamics were measured using the resin tube technique, with disturbed samples due to the high stoniness of the plots. Thirteen years after the experimental clearings, T100, T75 and T60 treatments showed a twofold increase in the net mineralization and nitrification rates with respect to T0 in both blocks (TU and CH). Within the plots, the highest mineralization was found in sites with no plant cover followed by those covered by undergrowth. These results can be explained in terms of the different litterfall qualities, which in turn are the result of the proportion of material originating from Pinus halepensis Mill. vs. more decomposable undergrowth residues.

Effect of landscape position on N mineralization and nitrification in a forested watershed in the Adirondack Mountains of New York

1999 ◽  
Vol 29 (4) ◽  
pp. 497-508 ◽  
Author(s):  
Kiyokazu Ohrui ◽  
Myron J Mitchell ◽  
Joseph M Bischoff
Keyword(s):  
New York ◽  
N Mineralization ◽  
Forest Floor ◽  
Landscape Position ◽  
Nitrification Rate ◽  
Forested Watershed ◽  
Net N Mineralization ◽  
Adirondack Mountains ◽  
Net Nitrification ◽  
Intermediate Rate

Within a forest ecosystem in the Adirondack Mountains of New York, net N mineralization and nitrification rates were measured at different landscape positions (zones). Net N mineralization rates (0-15 cm depth) were less (39 kg N·ha-1 per year) within a wetland without alder and with a coniferous overstory than an upland conifer zone (82 kg N·ha-1 per year) and an upland hardwood zone (107 kg N·ha-1 per year). Net N mineralization rates (39 to 82 kg N·ha-1 per year) and the forest floor N concentrations (2.3 to 2.5%) were higher than values reported (1.2-29 kg N·ha-1 and 1.1-2.12%, respectively) for other spruce forests. The net nitrification rates were higher at the upland hardwood zone (29 kg N·ha-1 per year) than the upland conifer zone (2 kg N·ha-1 per year). The wetland conifer zone without alders had an intermediate rate of net nitrification (13 kg N·ha-1 per year) compared with the upland zones. The presence of white alder (Alnus incana (L.) Moench) in the wetland increased the NO3- content and net nitrification rate of the soil.

Different nitrogen sources for fertilizing western hemlock in western Washington

1984 ◽  
Vol 14 (2) ◽  
pp. 155-162 ◽  
Author(s):  
M. A. Radwan ◽  
D. S. DeBell ◽  
S. R. Webster ◽  
S. P. Gessel
Keyword(s):  
Forest Floor ◽  
Mineral Soil ◽  
Volume Growth ◽  
Basal Area ◽  
N Fertilization ◽  
Height Growth ◽  
Growth Responses ◽  
Total N ◽  
Area Growth ◽  
Western Washington

Effects of different sources of fertilizer N on selected chemical characteristics of soils and foliage, and on growth of western hemlock (Tsugaheterophylla (Raf.) Sarg.) were compared at three different sites in western Washington. Treatments were the following: untreated control (O), ammonium nitrate (AN), ammonium sulfate (AS), calcium nitrate (CN), urea (U), and urea – ammonium sulfate (US). Fertilizers were applied in the spring (April–May) at 224 kg N/ha. Forest floor and mineral soil, to a depth of 5 cm, and foliage were sampled periodically for 2 years. Height and diameter of selected trees were measured periodically for 4 years. Results are reported mostly for two sites, one in the Cascade Range and one in the coastal zone in western Washington. The pH of forest floor and mineral soil varied by treatment, and the two urea fertilizers caused substantial initial rise. Effects on soil and foliar nutrients varied by fertilizer, sampling date, and location. In general, all fertilizers increased NH4 N, N03 N, and total N in the forest floor and mineral soil, and total N in the foliage. Also, with some exceptions, especially with foliar P in the Cascade site, fertilization reduced foliar content of important nutrients. At the Cascade site, 4-year growth responses in height, basal area, and volume averaged over all fertilizers were 30, 34, and 32%, respectively. AN, AS, CN, and urea resulted in height growth significantly (P < 0.20) higher than that of the control. Significant basal area growth and volume-growth responses were produced by AN, CN, and US. No significant height-growth response to any fertilizer occurred in the coastal stand; basal area growth and volume-growth responses averaged 27 and 21%, respectively, and best response occurred with urea. These results suggest that the low and inconsistent response of hemlock to N fertilization cannot be improved by applying some N fertilizer other than urea. Factors limiting response to N fertilization may be associated with availability of native N and other nutrients or other characteristics of hemlock sites and stands.

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.

Nitrogen availability in forest floors of three tree species on the same site: the role of litter quality

2000 ◽  
Vol 30 (11) ◽  
pp. 1698-1706 ◽  
Author(s):  
K D Thomas ◽  
C E Prescott
Keyword(s):  
Nitrogen Mineralization ◽  
Tree Species ◽  
N Mineralization ◽  
Forest Floor ◽  
Lodgepole Pine ◽  
Douglas Fir ◽  
Net N Mineralization ◽  
N Concentration ◽  
Paper Birch ◽  
Forest Floors

Forest floor samples from a 25-year-old plantation of three tree species (Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.), and paper birch (Betula papyrifera Marsh.)) growing on the same site were incubated (aerobically) in the laboratory for 29 days. Rates of N mineralization in the forest floors of Douglas-fir (165.1 µg/g) was significantly greater than either birch (72.9 µg/g) or lodgepole pine (51.2 µg/g). Douglas-fir forest floors also had the highest N concentration, lowest C/N ratio, and highest NH4-N concentrations, followed by paper birch and lodgepole pine. Douglas-fir forest floors also mineralized more N per unit of either N or C than the other species. There were no differences in rates of CO2-C mineralization in forest floors among the three species. Nitrogen mineralization rates were positively correlated with the N concentration of the forest floor (r2 = 0.81) and also with the C/N and NH4-N concentration of the forest floor. Nitrogen concentration, C/N, and lignin/N of foliar litter were poor predictors of N mineralization rates resulting from Douglas-fir litter having the lowest N concentrations in litter but the highest rates of net N mineralization in the forest floor. Nitrogen mineralization in the forest floor was negatively correlated (r2 = 0.67) with the lignin concentration in foliar litter. Douglas-fir litter had low lignin concentrations, which may allow more of the mineralized N to remain in inorganic forms rather than being bound in humus. Our results suggest that a component of Douglas-fir might improve N availability in coniferous forest floors.

Clearcut harvesting effects on soil and creek inorganic nitrogen in high elevation forests of southern interior British Columbia

2009 ◽  
Vol 89 (1) ◽  
pp. 35-44 ◽  
Author(s):  
Graeme D Hope
Keyword(s):  
British Columbia ◽  
N Mineralization ◽  
Stream Water ◽  
Inorganic Nitrogen ◽  
High Elevation ◽  
Net N Mineralization ◽  
Engelmann Spruce ◽  
Annual Peak ◽  
Clearcut Harvesting ◽  
Exchange Resins

Responses of both soil and stream inorganic nitrogen (N) after operational clearcut harvesting were explored in two high elevation British Columbia Engelmann spruce-Subalpine fir (ESSF) forests. At one study site, net N mineralization was measured between 1 and 11 yr after harvest. At a second site, for 3 yr after harvesting, available soil ammonium and nitrate were measured using ion exchange resins, and drainage losses of N were estimated using tension lysimeters and soil water balance models. Stream water N concentrations were also measured in one unlogged, and two logged watersheds at the second study area for 12 yr, both pre- and post-clearcut harvesting. Growing season as well as over-winter increases in post-harvest soil nitrate were detected after 3 yr, and the increases were apparent for up to 11 yr. Seasonal losses of N in drainage were greater in clearcut soils than in the forest soils in year 2 for ammonium and in years 2 and 3 for nitrate. A high proportion of the N was lost in drainage during snowmelt. Stream water ammonium in all three streams and nitrate in the unlogged and one harvested creek remained at or below the detection level. In the third creek, the frequency of detection and concentrations of nitrate peaked 2 to 3 yr after 30 to 57% of the watershed was harvested. The annual peak in NO3-N concentrations occurred immediately before the snowmelt-driven stream flow peak. Drainage losses and stream N fluxes were both small, relative to the total soil N content. Key words: Nitrogen, N mineralization, nitrate, harvesting, leaching, stream N, snowmelt

scholarly journals Factors Influencing Spatial Variability in Nitrogen Processing in Nitrogen-Saturated Soils

2001 ◽  
Vol 1 ◽  
pp. 505-513 ◽  
Author(s):  
Frank S. Gilliam ◽  
Frank C.C. Somerville ◽  
Frank N.L. Lyttle ◽  
Frank M.B. Adams
Keyword(s):  
Spatial Variability ◽  
N Mineralization ◽  
Forest Floor ◽  
Mineral Soil ◽  
Nitrifying Bacteria ◽  
Saturated Soils ◽  
N Saturation ◽  
Net N Mineralization ◽  
Net Nitrification ◽  
Floor Material

Nitrogen (N) saturation is an environmental concern for forests in the eastern U.S. Although several watersheds of the Fernow Experimental Forest (FEF), West Virginia exhibit symptoms of N saturation, many watersheds display a high degree of spatial variability in soil N processing. This study examined the effects of temperature on net N mineralization and nitrification in N-saturated soils from FEF, and how these effects varied between high N-processing vs. low N-processing soils collected from two watersheds, WS3 (fertilized with [NH4]2SO4) and WS4 (untreated control). Samples of forest floor material (O1 horizon) and mineral soil (to a 5-cm depth) were taken from three subplots within each of four plots that represented the extremes of highest and lowest rates of net N mineralization and nitrification (hereafter, high N and low N, respectively) of untreated WS4 and N-treated WS3: control/low N, control/high N, N-treated/low N, N-treated/high N. Forest floor material was analyzed for carbon (C), lignin, and N. Subsamples of mineral soil were extracted immediately with 1 N KCl and analyzed for NH4+ and NO3-to determine preincubation levels. Extracts were also analyzed for Mg, Ca, Al, and pH. To test the hypothesis that the lack of net nitrification observed in field incubations on the untreated/low N plot was the result of absence of nitrifier populations, we characterized the bacterial community involved in N cycling by amplification of amoA genes. Remaining soil was incubated for 28 d at three temperatures (10, 20, and 30°C), followed by 1 NKCl extraction and analysis for NH4+and NO3-. Net nitrification was essentially 100% of net N mineralization for all samples combined. Nitrification rates from lab incubations at all temperatures supported earlier observations based on field incubations. At 30°C, rates from N-treated/high N were three times those of N-treated/low N. Highest rates were found for untreated/high N (two times greater than those of N-treated/high N), whereas untreated/low N exhibited no net nitrification. However, soils exhibiting no net nitrification tested positive for presence of nitrifying bacteria, causing us to reject our initial hypothesis. We hypothesize that nitrifier populations in such soil are being inhibited by a combination of low Ca to Al ratios in mineral soil and allelopathic interactions with mycorrhizae of ericaceous species in the herbaceous layer.

Nitrogen budget for fertilized carrot cropping systems in a Quebec organic soil

2014 ◽  
Vol 94 (2) ◽  
pp. 139-148 ◽  
Author(s):  
Jean Caron ◽  
Guillaume Théroux Rancourt ◽  
Carl Bélec ◽  
Nicolas Tremblay ◽  
Léon-Étienne Parent
Keyword(s):  
Crop Yield ◽  
Nitrate Leaching ◽  
N Mineralization ◽  
Cropping Systems ◽  
Organic Soil ◽  
N Fertilization ◽  
Nitrogen Budget ◽  
Nitrate Content ◽  
Net N Mineralization ◽  
Soil N

Caron, J., Rancourt, G. T., Bélec, C., Tremblay, N. and Parent, L.-É. 2014. Nitrogen budget for fertilized carrot cropping systems in a Quebec organic soil. Can. J. Soil Sci. 94: 139–148. After reclamation, organic soils tend to shift from net N immobilization to net N mineralization. The N amounts mineralized annually can be sufficient to cover the N needs of the crop, reducing the need for supplemental N fertilization. The objective of this study was to assess N budgets and to infer the apparent N mineralization in fertilized and unfertilized carrot (Daucus carota L.) crops in an organic soil in southwestern Quebec. Five pre-plant N fertilization treatments (0, 25, 50, 75, and a split 25+25 kg N ha−1) were applied over a 3-yr period to non-irrigated carrots. Crop yield and plant and soil N contents were measured. Apparent net N mineralization was an important source of N, averaging 117 kg N ha−1yr−1. Crop yield was not affected by the N fertilization rate, by splitting of the fertilizer application or by the previous year’s crop. Increasing the N fertilizer rate increased the soil nitrate content below the root zone (∼40 cm below the surface), enhancing the risk of nitrate leaching. Thus, because soil N mineralization was sufficient for the carrots’ requirements in this organic soil, supplemental N fertilization was found to be unnecessary and could exacerbate the environmental risk of nitrate leaching.

Nitrogen mineralization and decomposition in forest floors in adjacent plantations of western red cedar, western hemlock, and Douglas-fir

1994 ◽  
Vol 24 (12) ◽  
pp. 2424-2431 ◽  
Author(s):  
C.E. Prescott ◽  
C.M. Preston
Keyword(s):  
Mass Loss ◽  
N Mineralization ◽  
Forest Floor ◽  
Douglas Fir ◽  
Western Hemlock ◽  
N Availability ◽  
Net N Mineralization ◽  
Red Cedar ◽  
Western Red Cedar ◽  
Forest Floors

To determine if western red cedar (Thujaplicata Donn) litter contributes to low N availability in cedar–hemlock forests, we measured concentrations of N and rates of net N mineralization in forest floors from single-species plantations of cedar, western hemlock (Tsugaheterophylla (Raf.) Sarg.), and Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) on the same site in coastal British Columbia. Concentrations of total and extractable N and rates of net N mineralization during laboratory incubations were lowest in the cedar forest floor and highest in Douglas-fir. Less C was mineralized in the cedar forest floor during incubation, and the amount of N mineralized per unit C was least in cedar. Rates of mass loss of foliar litter of the three species were similar during the first 50 weeks of a 70-week laboratory incubation, but cedar lost mass more quickly during the final 20 weeks. Rates of net N mineralization in the forest floors were significantly correlated with the initial percent N, C/N, % Klason lignin, and lignin/N of foliar litter. Foliar litter of cedar had lower concentrations of N and greater proportions of alkyl C (based on 13C NMR spectroscopy) than Douglas-fir litter. These characteristics of cedar litter may contribute to low N availability in cedar–hemlock forest floors. Concentrations of alkyl C (waxes and cutin) may be better than lignin for predicting rates of mass loss and N mineralization from litter.

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