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14 results for “nitrogen amendment”
20-Year Root Mass in Chronic Nitrogen Amendment Experiment at Harvard Forest 2008
Forests typically respond to nitrogen additions with increased productivity, hence a long-held paradigm was that chronic additions of anthropogenically-derived atmospheric deposition would have positive ecosystem effects. However, twenty years of work at the Harvard Forest Chronic N Deposition plots, and in other forest ecosystems as well, has shown that that this simplistic view is incomplete. For example, enhanced ammonium uptake increases soil acidity, leading to mobilization of aluminum, and loss of nutrient cations (e.g. Mg2+, Ca2+, and K+ ) all of which influence root mass, turnover, and activity. To address long-term impacts of N additions on forest root mass, we removed O-horizon (forest floor) samples from the Chronic N hardwood and red pine stands to quantify the total mass of roots. We found that long term N additions had contrasting results in the two forests. In the hardwood plots, total root mass (less than 2mm) increased from 0.167 + 0.026 (S.E.) kg m-2 in the control plot to 0.434 + 0.170 kg m-2 in the high N plots. In contrast, in the red pine stand, roots declined from 0.074 + 0.011 (S.E.) kg m-2 in the control plot to 0.031 + 0.016 kg m-2 in the high N plots. These data are in agreement with data for aboveground productivity at the Chronic N plots, which show stimulated growth in the hardwoods and severe growth declines and enhanced mortality in the pine stand.
Foliar and Soil Chemistry at Harvard Forest Chronic Nitrogen Amendment Experiment 1995-2009
The aim of the chronic N study at Harvard Forest is to increase our understanding of ecosystem nitrogen dynamics in response to elevated nitrogen inputs. In recent, nitrogen deposition in the Northeastern United States has been 10 to 20 times above historic background levels which could possibly saturate the retention capacity of a forest ecosystem. Long-term elevated N deposition typically leads to an increase in the concentration of total foliar N, with or without similar changes in the important base elements such as Ca, Mg and K. This increase in leaf N content also leads to significant shifts in the internal partitioning of N within the leaf. For example, in conifers, N deposition has been shown to significantly increase leaf N present in the form of free amino acids such as arginine. Little is known about N partitioning for hardwoods under these conditions. These changes in N partitioning are possibly connected to leaf function. The present study was conducted to experimentally test whether the alterations in N partitioning do occur due to long-term N deposition and if so do they have a positive or a negative effect on photosynthetic capacity and biomass production. A possible decoupling of the relationship between foliar N and photosynthetic rate may occurs under these conditions. The treatment plots used in this study are part of the Chronic Nitrogen Amendment Study at the Harvard Forest LTER site (42.5°N, 72°W). The site has a temperate climate with monthly temperatures ranging from -7°C in January to 20°C in July. Average annual precipitation is 110 cm (http://harvardforest.fas.harvard.edu). The site averages approximately 8 kg ha-1 year-1 of total N deposition. As reported earlier, the land-use history of the pine and hardwood stands used in this study is very different. Two adjacent stands were chosen for the study: an even-aged red pine (Pinus resinosa Ait.) stand and a 50-year-old mixed hardwood stand that had regenerated naturally after clearcutting i
Chronic Nitrogen Amendment Experiment at Harvard Forest since 1988
The purpose of this study is to increase our understanding of ecosystem nitrogen dynamics in response to elevated nitrogen inputs. With atmospheric nitrogen deposition in the Northeastern United States currently at 10 to 20 times above historic background levels, it is possible that excessive nitrogen inputs could saturate the retention capacity of a forest ecosystem. Potential effects of nitrogen saturation include increased nitrate leaching and simultaneous base cation losses, soil acidification, altered fluxes of trace gases and forest decline. Two adjacent stands were chosen for the study: an even-aged red pine (Pinus resinosa Ait.) stand planted in 1926 and a 50-year-old mixed hardwood stand that had regenerated naturally after clearcutting in approximately 1945. The hardwood stand is dominated by black and red oak (Quercus velutina Lam.; Q. rubra L.) with significant amounts of black birch (Betula lenta L.), red maple (Acer rubrum L.) and American beech (Fagus grandifolia Ehrh.). The dominant soil types are stony- to sandy-loams formed from glacial till, and are classified as Typic Dystrochrepts of the Canton or Montauk series. Four treated plots were established within each stand: control, low N, low N plus sulfur (N+S) and high N. Each plot measures 30 x 30 meters (0.09 ha) and is divided into thirty-six 5 x 5 m subplots.
Effects of microarthropod exclusion and water amendments on fluffgrass rhizosphere nitrogen mineralization potential at the Jornada Basin LTER site in 1987
This data package contains data on soil nitrogen mineralization potential in the rhizosphere of fluffgrass (Dasyochloa pulchella) plants from 1987. This study was conducted at the Chihuahuan Desert Rangeland Research Center to test how watering, and changing densities of soil microarthropods and nematodes, impacts fluffgrass growth and nutrient cycling. Twenty 6 x 6 m plots were established with a 3 m buffer between plots. Five plots were randomly assigned to one of four treatments:1) Chlordane (to exclude microarthropods), 2) Chlordane and water, 3) Water, and 4) Control. Three randomly located subsamples were taken from each plot and consisted of the fluff grass plant, a 10 cm in diameter and 15 cm deep soil core centered on each plant. Samples were incubated for 0, 2, 4, or 8 weeks. This data set contains information on the incubation time, soil nitrate (NO3-), soil ammonium (NH4+), and soil water content for each subsample. This data were collected in May 1987 and the study is complete.
Effects of microarthropod exclusion and water amendments on fluffgrass tissue nitrogen at the Jornada Basin LTER site in 1986
This data package contains fluff grass (Dasyochloa pulchella) tissue nitrogen data from plants collected at the Jornada Basin LTER site in southern New Mexico, USA, in 1987. The purpose of this study was to test how watering, and changing densities of soil microarthropods and nematodes, results in changes in fluff grass growth and nitrogen acquisition. Twenty 6 x 6 m plots were established with a 3 m buffer between plots. Five plots were randomly assigned to one of four treatments: 1) Chlordane to exclude microarthropods, 2) Chlordane and water, 3) Water, and 4) Control. For four consecutive months, randomly selected fluff grass plants were collected from each plot and the flowers, green leaves, and grey leaves were separated for total nitrogen digestion analysis and dry weight measurement. This data set consists of sampling date, treatment, plant matter, total nitrogen (mg/g) and dry weight (g). Data was collected in 1987 and the study is complete.
Effects of microarthropod exclusion and water amendments on fluffgrass growth, root nitrogen, and mite and nematode abundance at the Jornada Basin LTER site, 1986-1987
This data package contains data on microarthropods, nematodes, fluff-grass (Dasyochloa pulchella) growth, and root nitrogen in samples from study plots sampled approximately monthly between May 1986 and August 1987 at the Jornada Basin LTER site in southern New Mexico USA. The purpose of this study was to test how watering, and changing densities of soil microarthropods and nematodes, results in changes in fluff grass growth and root nitrogen. Twenty 6 x 6 m plots were established with a 3 m buffer between plots. Five plots were randomly assigned to one of four treatments: 1) Chlordane to exclude microarthropods, 2) Chlordane and water, 3) Water, and 4) Control. At monthly intervals, randomly selected fluff grass plants were collected from each plot. This data set consists of plant diameters (cm), mite soil weight (g), root weight (g), nematode soil weight (g), root total nitrogen (mg/g), and nematode number. This study was completed in November 1987.
Effects of microarthropod exclusion and water amendments on fluffgrass rhizosphere total soil nitrogen at the Jornada Basin, 1986-1987
This data package contains data on soil nitrogen content in the rhizosphere of fluff grass (Dasyochloa pulchella) plants collected from 1986-1987 at the Jornada Basin LTER site. The purpose of this study was to test how watering, and changing densities of soil microarthropods and nematodes, results in changes in fluff grass rhizosphere total nitrogen. Twenty 6 x 6 m plots were established with a 3 m buffer between plots. Five plots were randomly assigned to one of four treatments: 1) Chlordane to exclude microarthropods, 2) Chlordane and water, 3) Water, and 4) Control. Every three months from June 1986 to January 1987, randomly selected fluff grass plants were harvested from each plot and rhizosphere soil samples were collected for total nitrogen digestion analysis. This data set consists of sampling date, treatment, subsample number, and total nitrogen (mg/kg). This study was completed in January 1987.
Nitrogen enrichment stimulates wetland plant responses whereas salt amendments alter sediment microbial communities and biogeochemical responses
<p>Freshwater wetlands of the temperate north are exposed to a range of pollutants that may alter their function, including nitrogen (N)-rich agricultural and urban runoff, seawater intrusion, and road salt contamination, though it is largely unknown how these drivers of change interact with the vegetation to affect wetland carbon (C) fluxes and microbial communities. We implemented a full factorial mesocosm (378.5 L tanks) experiment investigating C-related responses to three common wetland plants of eastern North America (<i>Phragmites australis</i>, <i>Spartina pectinata</i>, <i>Typha latifolia</i>), and four water quality treatments (fresh water control, N, road salt, sea salt). During the 2017 growing season, we quantified carbon dioxide (CO<sub>2</sub>) and methane (CH<sub>4</sub>) fluxes, above- and below-ground biomass, root porosity, light penetration, pore water chemistry (NH<sub>4</sub><sup>+</sup>, NO<sub>3</sub><sup>-</sup>, SO<sub>4</sub><sup>-</sup>², Cl<sup>-</sup>, DOC), soil C mineralization, as well as sediment microbial communities via 16S rRNA gene sequencing. Relative to freshwater controls, N enrichment stimulated plant biomass, which in turn increased CO<sub>2</sub> uptake and reduced light penetration, especially in <i>Spartina</i> stands. Root porosity was not affected by water quality, but was positively correlated with CH<sub>4 </sub>emissions,<sub> </sub>suggesting that plants can be important conduits for CH<sub>4</sub> from anoxic sediment to the atmosphere. Sediment microbial composition was largely unaffected by N addition, whereas salt amendments induced structural shifts, reduced sediment community diversity, and reduced C mineralization rates, presumably due to osmotic stress. Methane emissions were suppressed by sea salt, but not road salt, providing evidence for the additional chemical control (SO<sub>4</sub><sup>-2</sup> availability) on this microbial-mediated process. Thus, N may have stimulated plant activity while salting treatments preferentially enriched specific microbial populations. Together our findings underpin the utility of combining plant and microbial responses, and highlight the need for more integrative studies to predict the consequences of a changing environment on freshwater wetlands. </p>
Nitrogen enrichment stimulates wetland plant responses whereas salt amendments alter sediment microbial communities and biogeochemical responses
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Data from: Phosphorus amendment mitigates nitrogen addition-induced phosphorus limitation in two plant species in a desert steppe, China
Background and aims: The increasing deposition of atmospheric nitrogen (N) due to anthropogenic activities has significantly enhanced N inputs to ecosystems, resulting in an imbalance in the N: phosphorus (P) ratios in plants and soils. This study aimed to determine whether, and to what extent, P addition alleviates N-induced P limitation in a desert steppe ecosystem. Methods: We conducted a multi-level N:P supply experiment (i.e., constant N with varied P-addition levels) for a grass species, Pennisetum centrasiaticum, and a N-fixing species, Glycyrrhiza uralensis. Results: With increasing amounts of P addition (thereby decreasing the N:P ratio), green-leaf P concentrations of the two species studied tended to increase, while P-resorption proficiency and efficiency tended to decrease. There were no consistent trends in green-leaf N concentrations in response to P addition. However, both species exhibited high N-resorption proficiency, especially in G. uralensis, with high P addition. Generally, the carbon (C):P and N:P ratios both in soils and in green leaves had positive relationships with green-leaf N concentration and P-resorption proficiency of P. centrasiaticum as well as P-resorption traits of G. uralensis, but negative relationships with green-leaf P concentrations in both species. Conclusions: Our study indicates that P addition can alter P-conservation strategy and thereby releasing plant species from the N-induced imbalance of N:P ratios. However, large amounts of P addition could overcompensate and pose a risk of N limitation in desert steppe ecosystems.
Data from: Annual ryegrass (Lolium multiflorum Lam.) growth response to nitrogen in a sandy soil amended with acidified manure and municipal sludge after "Quick Wash" treatment
<p>The Quick Wash (QW) treatment extracts phosphorus (P) from manure and municipal sludge (MS), producing an organic acidified by-product with adequate nitrogen (N):P ratio to meet crop N requirements. Yet, data on crop response to N using QW by-products are lacking. We evaluated the response of annual ryegrass (<span class="html-italic">Lolium multiflorum</span> Lam.) and potential N leaching in sandy soil to N applications using raw wastes, their corresponding QW by-products, and ammonium sulfate (AMS) fertilizer. Treatments included a control (no amendment added), raw and acid-washed chicken litter, dairy and swine manure, MS, and AMS at 100, 200, and 400 kg N ha<sup>−1</sup>.</p>
Data from: Phosphorus amendment mitigates nitrogen addition-induced phosphorus limitation in two plant species in a desert steppe, China
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Data from: Annual ryegrass (Lolium multiflorum Lam.) growth response to nitrogen in a sandy soil amended with acidified manure and municipal sludge after “Quick Wash” treatment
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Expression analysis from glass-bead cultures of Paxillus involutus (ATCC200175) after amendments of nitrogen (+/-NH4) to substrate followed by incubation for different periods of time
GEO Series GSE47839. Paxillus involutus ATCC 200175; Paxillus involutus. 12 samples. Type: Expression profiling by array.
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