scholarly journals Nitrogen Fertilization and Native C4 Grass Species Alter Abundance, Activity, and Diversity of Soil Diazotrophic Communities

2021 ◽  
Vol 12 ◽  
Author(s):  
Jialin Hu ◽  
Jonathan D. Richwine ◽  
Patrick D. Keyser ◽  
Lidong Li ◽  
Fei Yao ◽  
...  
Keyword(s):  
Population Size ◽  
Community Composition ◽  
Nitrogen Fertilization ◽  
N Fertilization ◽  
Equation Modeling ◽  
Grass Species ◽  
N Fixation ◽  
N Availability ◽  
The Impact ◽  
Diazotrophic Community

Native C4 grasses have become the preferred species for native perennial pastures and bioenergy production due to their high productivity under low soil nitrogen (N) status. One reason for their low N requirement is that C4 grasses may benefit from soil diazotrophs and promote biological N fixation. Our objective was to evaluate the impact of N fertilization rates (0, 67, and 202 kg N ha–1) and grass species (switchgrass [Panicum virgatum] and big bluestem [Andropogon gerardii]) on the abundance, activity, diversity, and community composition of soil diazotrophs over three agricultural seasons (grass green-up, initial harvest, and second harvest) in a field experiment in East Tennessee, United States. Nitrogen fertilization rate had a stronger influence on diazotroph population size and activity (determined by nifH gene and transcript abundances) and community composition (determined by nifH gene amplicon sequencing) than agricultural season or grass species. Excessive fertilization (202 kg N ha–1) resulted in fewer nifH transcripts compared to moderate fertilization (67 kg N ha–1) and decreased both richness and evenness of diazotrophic community, reflecting an inhibitory effect of high N application rates on soil diazotrophic community. Overall, cluster I and cluster III diazotrophs were dominant in this native C4 grass system. Diazotroph population size and activity were directly related to soil water content (SWC) based on structural equation modeling. Soil pH, SWC, and C and N availability were related to the variability of diazotrophic community composition. Our results revealed relationships between soil diazotrophic community and associated soil properties, adding to our understanding of the response of soil diazotrophs to N fertilization and grass species in native C4 grass systems.

scholarly journals Insights into mechanisms governing forest carbon response to nitrogen deposition: a model–data comparison using observed responses to nitrogen addition

2013 ◽  
Vol 10 (6) ◽  
pp. 3869-3887 ◽  
Author(s):  
R. Q. Thomas ◽  
G. B. Bonan ◽  
C. L. Goodale
Keyword(s):  
Plant Uptake ◽  
Temperate Forest ◽  
Growth Response ◽  
N Fertilization ◽  
N Deposition ◽  
Forest Carbon ◽  
Biogeochemical Model ◽  
N Fixation ◽  
N Availability ◽  
Fertilization Experiments

Abstract. In many forest ecosystems, nitrogen (N) deposition enhances plant uptake of carbon dioxide, thus reducing climate warming from fossil fuel emissions. Therefore, accurately modeling how forest carbon (C) sequestration responds to N deposition is critical for understanding how future changes in N availability will influence climate. Here, we use observations of forest C response to N inputs along N deposition gradients and at five temperate forest sites with fertilization experiments to test and improve a global biogeochemical model (CLM-CN 4.0). We show that the CLM-CN plant C growth response to N deposition was smaller than observed and the modeled response to N fertilization was larger than observed. A set of modifications to the CLM-CN improved the correspondence between model predictions and observational data (1) by increasing the aboveground C storage in response to historical N deposition (1850–2004) from 14 to 34 kg C per additional kg N added through deposition and (2) by decreasing the aboveground net primary productivity response to N fertilization experiments from 91 to 57 g C m−2 yr−1. Modeled growth response to N deposition was most sensitive to altering the processes that control plant N uptake and the pathways of N loss. The response to N deposition also increased with a more closed N cycle (reduced N fixation and N gas loss) and decreased when prioritizing microbial over plant uptake of soil inorganic N. The net effect of all the modifications to the CLM-CN resulted in greater retention of N deposition and a greater role of synergy between N deposition and rising atmospheric CO2 as a mechanism governing increases in temperate forest primary production over the 20th century. Overall, testing models with both the response to gradual increases in N inputs over decades (N deposition) and N pulse additions of N over multiple years (N fertilization) allows for greater understanding of the mechanisms governing C–N coupling.

scholarly journals Insights into mechanisms governing forest carbon response to nitrogen deposition: a model-data comparison using observed responses to nitrogen addition

2013 ◽  
Vol 10 (1) ◽  
pp. 1635-1683 ◽  
Author(s):  
R. Q. Thomas ◽  
G. B. Bonan ◽  
C. L. Goodale
Keyword(s):  
Plant Uptake ◽  
Temperate Forest ◽  
Growth Response ◽  
N Fertilization ◽  
N Deposition ◽  
Forest Carbon ◽  
Biogeochemical Model ◽  
N Fixation ◽  
N Availability ◽  
Fertilization Experiments

Abstract. In many forest ecosystems, nitrogen (N) deposition enhances plant uptake of carbon dioxide, thus reducing climate warming from fossil fuel emissions. Therefore, accurately modeling how forest carbon (C) sequestration responds to N deposition is critical for understanding how future changes in N availability will influence climate. Here, we use observations of forest C response to N inputs along N deposition gradients and at five temperate forest sites with fertilization experiments to test and improve a~global biogeochemical model (CLM-CN 4.0). We show that the CLM-CN plant C growth response to N deposition was smaller than observed and the modeled response to N fertilization was larger than observed. A set of modifications to the CLM-CN improved the correspondence between model predictions and observational data (1) by increasing the aboveground C storage in response to historical N deposition (1850–2004) from 14 to 34 kg C per additional kg N added through deposition and (2) by decreasing the aboveground net primary productivity response to N fertilization experiments from 91 to 57 g C m−2 yr−1. Modeled growth response to N deposition was most sensitive to altering the processes that control plant N uptake and the pathways of N loss. The response to N deposition also increased with a more closed N cycle (reduced N fixation and N gas loss) and decreased when prioritizing microbial over plant uptake of soil inorganic N. The net effect of all the modifications to the CLM-CN resulted in greater retention of N deposition and a greater role of synergy between N deposition and rising atmospheric CO2 as a mechanism governing increases in temperate forest primary production over the 20th century. Overall, testing models with both the response to gradual increases in N inputs over decades (N deposition) and N pulse additions of N over multiple years (N fertilization) allows for greater understanding of the mechanisms governing C-N coupling.

Mineralization and immobilization of soil nitrogen in two Douglas-fir stands 15 and 22 years after nitrogen fertilization

1989 ◽  
Vol 19 (6) ◽  
pp. 798-801 ◽  
Author(s):  
Russell H. Strader ◽  
Dan Binkley
Keyword(s):  
Nitrogen Fertilization ◽  
N Fertilization ◽  
Douglas Fir ◽  
Soil Samples ◽  
N Availability ◽  
Microbial Immobilization ◽  
Mineral N ◽  
Net Mineralization ◽  
Infertile Soils

Additions of 15N-labelled ammonium chloride were used to examine the role of microbial immobilization in long-term growth response of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) plantations to nitrogen fertilization. Soil samples were collected in the summer of 1986 from fertilized (448 or 470 kg N/ha) and nonfertilized plots at previously established N fertilization experiments near Shawnigan Lake, British Columbia, and the Wind River Experimental Forest near Carson, Washington. Douglas-fir on these sites were reported to still be responding to N fertilization after 12 and 18 years. Less than 2% of the added 15N was recovered as mineral N after a 14-day laboratory incubation of soil samples from the fertilized and nonfertilized plots. This indicates that gross mineralization could be over 50 times greater than net mineralization in these infertile soils if the remaining 98% of the added 15N was all biologically immobilized. Net mineralization was significantly greater (p ≤ 0.10) in soils from the fertilized plots than in those from the non-fertilized plots at the Wind River site. Though the current differences in N availability did not appear to be related to differences in microbial immobilization, such large rates of immobilization warrant closer scrutiny as a factor in long-term response to fertilization.

scholarly journals The Effect of Nitrogen Fertilization on Tree Growth, Soil Organic Carbon and Nitrogen Leaching—A Modeling Study in a Steep Nitrogen Deposition Gradient in Sweden

Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 298
Author(s):  
Klas Lucander ◽  
Giuliana Zanchi ◽  
Cecilia Akselsson ◽  
Salim Belyazid
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Nitrogen Deposition ◽  
Tree Growth ◽  
Nitrogen Fertilization ◽  
Dynamic Models ◽  
N Fertilization ◽  
N Leaching ◽  
N Availability ◽  
N Saturation

Nitrogen (N) fertilization in forests has the potential to increase tree growth and carbon (C) sequestration, but it also means a risk of N leaching. Dynamic models can, if the important processes are well described, play an important role in assessing benefits and risks of nitrogen fertilization. The aim of this study was to test if the ForSAFE model is able to simulate correctly the effects of N fertilization when considering different levels of N availability in the forest. The model was applied for three sites in Sweden, representing low, medium and high nitrogen deposition. Simulations were performed for scenarios with and without fertilization. The effect of N fertilization on tree growth was largest at the low deposition site, whereas the effect on N leaching was more pronounced at the high deposition site. For soil organic carbon (SOC) the effects were generally small, but in the second forest rotation SOC was slightly higher after fertilization, especially at the low deposition site. The ForSAFE simulations largely confirm the N saturation theory which state that N will not be retained in the forest when the ecosystem is N saturated, and we conclude that the model can be a useful tool in assessing effects of N fertilization.

scholarly journals Salinity as a key control on the diazotrophic community composition in the Baltic Sea

2021 ◽  
Author(s):  
Christian Furbo Reeder ◽  
Ina Stoltenberg ◽  
Jamileh Javidpour ◽  
Carolin Regina Löscher
Keyword(s):  
Baltic Sea ◽  
Community Composition ◽  
N2 Fixation ◽  
Statistical Testing ◽  
Functional Marker ◽  
The Baltic Sea ◽  
Heterocystous Cyanobacteria ◽  
The Baltic ◽  
The Impact ◽  
Diazotrophic Community

Abstract. Over the next decade, the Baltic Sea is predicted to undergo severe changes including a decrease in salinity due to altering precipitation. This will likely impact the distribution and community composition of Baltic Sea N2 fixing microbes, of which especially heterocystous cyanobacteria are adapted to low salinities and may expand to waters with currently higher salinity, including the Danish Strait and Kattegat, while other high-salinity adapted N2 fixers might decrease in abundance. In order to explore the impact of salinity on the distribution and activity of different diazotrophic clades, we followed the natural salinity gradient from the Eastern Gotland and Bornholm Basins through the Arkona Basin to the Kiel Bight and combined N2 fixation rate measurements with a molecular analysis of the diazotrophic community using the key functional marker gene for N2 fixation nifH, as well as the key functional marker genes anf and vnf, encoding for the two alternative nitrogenases. We detected N2 fixation rates between 0.7 and 6 nmol N L-1 d-1, and the diazotrophic community was dominated by the cyanobacterium Nodularia and the small unicellular, cosmopolitan cyanobacterium UCYN-A. Nodularia was present in abundances between 8.07 x 105 and 1.6 x 107 copies L-1 in waters with salinities of 10 and below, while UCYN-A reached abundances of up to 4.5 x 107 copies L-1 in waters with salinity above 10. Besides those two cyanobacterial diazotrophs, we found several clades of proteobacterial N2 fixers and alternative nitrogenase genes associated with Rhodopseudomonas palustris, a purple non-sulfur bacterium. Based on statistical testing, salinity was identified as the primary parameter describing the diazotrophic distribution, while pH and temperature did not have a similarly significant influence on the diazotrophic distribution. While this statistical analysis will need to be explored in direct experiments, it gives an indication for a future development of diazotrophy in a freshening Baltic Sea with UCYN-A retracting to more saline North Sea waters and heterocystous cyanobacteria expanding as salinity decreases.

scholarly journals Shovelomics root traits assessed on the EURoot maize panel are highly heritable across environments but show low genotype-by-nitrogen interaction

Euphytica ◽  
2019 ◽  
Vol 215 (10) ◽  
Author(s):  
Chantal A. Le Marié ◽  
Larry M. York ◽  
Alexandre Strigens ◽  
Marcos Malosetti ◽  
Karl-Heinz Camp ◽  
...  
Keyword(s):  
Root System ◽  
Root Traits ◽  
N Fertilization ◽  
N Availability ◽  
Stay Green ◽  
N Application ◽  
Growth Environment ◽  
Root Stock ◽  
Horizontal Expansion ◽  
The Impact

Abstract The need for sustainable intensification of agriculture in the coming decades requires a reduction in nitrogen (N) fertilization. One opportunity to reduce N application rates without major losses in yield is breeding for nutrient efficient crops. A key parameter that influences nutrient uptake efficiency is the root system architecture (RSA). To explore the impact of N availability on RSA and to investigate the impact of the growth environment, a diverse set of 36 inbred dent maize lines crossed to the inbred flint line UH007 as a tester was evaluated for N-response over 2 years on three different sites. RSA was investigated by excavating and imaging of the root crowns followed by image analysis with REST software. Despite strong site and year effects, trait heritability was generally high. Root traits showing the greatest heritability (> 0.7) were the width of the root stock, indicative of the horizontal expansion, and the fill factor, a measure of the density of the root system. Heritabilities were in a similar range under high or low N application. Under N deficiency the root stock size decreased, the horizontal expansion decreased and the root stock became less dense. However, there was little differential response of the genotypes to low N availability. Thus, the assessed root traits were more constitutively expressed rather than showing genotype-specific plasticity to low N. In contrast, strong differences were observed for ‘stay green’ and silage yield, indicating that these highly heritable traits are good indicators for responsiveness to low N.

Fertilizer and rhizobial inoculant responses of chickpea on fallow and stubble sites in southern Alberta

2006 ◽  
Vol 86 (3) ◽  
pp. 685-692 ◽  
Author(s):  
R. H. McKenzie ◽  
A. B. Middleton ◽  
E. Bremer
Keyword(s):  
Cicer Arietinum ◽  
Water Use ◽  
Seed Yield ◽  
N Fertilization ◽  
N Fertilizer ◽  
N Availability ◽  
Minimum Requirement ◽  
Seed Protein Concentration ◽  
Southern Alberta ◽  
The Impact

Agronomic practices for chickpea (Cicer arietinum L.) production on the Canadian prairies are not well established. The objective of this study was to evaluate the impact of fallow on chickpea yield and response to rhizobia inoculation and fertilization. Field trials were conducted at nine fallow sites and nine stubble sites in southern Alberta over a 4-yr period (2000–2003). In the N experiment, N fertilizer was applied to rhizobia-inoculated and uninoculated desi (cv. Myles) and kabuli (cv. Sanford) chickpea at five N rates (0, 20, 40, 60 and 80 kg N ha-1). In the P experiment, P fertilizer was applied to desi chickpea at 0, 6.5 and 13 kg P ha-1. Growing season precipitation was well below normal during 3 of the 4 yr of this study, and fallow yields were more than double stubble yields. Desi seed yield increased 15.8 kg ha-1 for each millimetre increase in water use above a minimum requirement of 84 mm. Although nodulation of uninoculated chickpea was absent or very low at all sites, the benefits of inoculation were modest. On average, inoculation increased seed yield by 12%, seed protein concentration by 11%, and seed N yield by 24%. Inoculation responses were similar for fallow and stubble sites. Yield gains due to application of N fertilizer were also small at most sites, with no difference in yield gain between fallow and stubble sites. Yield benefits due to inoculation and N fertilization were often small because either moisture availability was low or soil N availability was high. Desi was more responsive to N fertilization than kabuli. Phosphorus fertilizer had a minimal impact on desi chickpea yield. Fallow had a large impact on chickpea yields, but did not affect rhizobia or fertilizer response. Key words: Cicer arietinum, yield, nitrogen, phosphorus, water use efficiency

scholarly journals Energy Use Efficiency of Biogas Production Depended on Energy Crops, Nitrogen Fertilization Level, and Cutting System

2020 ◽  
Vol 13 (4) ◽  
pp. 1069-1081
Author(s):  
Marta Oleszek ◽  
Mariusz Matyka
Keyword(s):  
Nitrogen Fertilization ◽  
Energy Use ◽  
Biogas Production ◽  
N Fertilization ◽  
Energy Crops ◽  
Energy Use Efficiency ◽  
Use Efficiency ◽  
Fertilization Level ◽  
The Impact ◽  
Cutting System

Abstract The paper evaluates the relation between energy input (Ei) and output (Eo) of biogas production from six energy crops: maize, sorghum, sunflower, triticale, reed canary grass (RCG), and Virginia mallow (VM), cultivated in three different nitrogen fertilization levels. Furthermore, in the case of RCG, the impact of cutting system was examined. The results showed that raised N fertilization dose (in the range of 40–120 kg ha−1 and 80–160 kg ha−1, depending on the crops) increased biomass yield and methane productivity (MP) but simultaneously caused also the increase in Ei. Nonetheless, the application of higher N doses did not cause drastic decrease in energy use efficiency (EUE). The Ei was significantly lower for perennials than for annual crops. For this reason, EUE for RCG harvested in two cuts (5.0–5.2 GJ GJ−1) was close to EUE for maize (5.7–6.8 GJ GJ−1), despite the much lower MP (2027–2903 m3 ha−1 and 4409–5692 m3 ha−1, respectively) and Eo (73–105 GJ ha−1 and 159–205 GJ ha−1, respectively). Furthermore, the collection of RCG in more than two cuts turned out to be unjustified, due to increase in Ei and, simultaneously, decrease in MP.

scholarly journals Long-Term Warming in Alaska Enlarges the Diazotrophic Community in Deep Soils

mBio ◽  
2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Jiajie Feng ◽  
C. Ryan Penton ◽  
Zhili He ◽  
Joy D. Van Nostrand ◽  
Mengting M. Yuan ◽  
...  
Keyword(s):  
Community Composition ◽  
Plant Biomass ◽  
Soil Depth ◽  
Global Climate ◽  
N Availability ◽  
Available N ◽  
Soil C ◽  
Winter Warming ◽  
Tundra Ecosystem ◽  
Diazotrophic Community

ABSTRACTTundra ecosystems are typically carbon (C) rich but nitrogen (N) limited. Since biological N2fixation is the major source of biologically available N, the soil N2-fixing (i.e., diazotrophic) community serves as an essential N supplier to the tundra ecosystem. Recent climate warming has induced deeper permafrost thaw and adversely affected C sequestration, which is modulated by N availability. Therefore, it is crucial to examine the responses of diazotrophic communities to warming across the depths of tundra soils. Herein, we carried out one of the deepest sequencing efforts of nitrogenase gene (nifH) to investigate how 5 years of experimental winter warming affects Alaskan soil diazotrophic community composition and abundance spanning both the organic and mineral layers. Although soil depth had a stronger influence on diazotrophic community composition than warming, warming significantly (P < 0.05) enhanced diazotrophic abundance by 86.3% and aboveground plant biomass by 25.2%. Diazotrophic composition in the middle and lower organic layers, detected bynifHsequencing and a microarray-based tool (GeoChip), was markedly altered, with an increase of α-diversity. Changes in diazotrophic abundance and composition significantly correlated with soil moisture, soil thaw duration, and plant biomass, as shown by structural equation modeling analyses. Therefore, more abundant diazotrophic communities induced by warming may potentially serve as an important mechanism for supplementing biologically available N in this tundra ecosystem.IMPORTANCEWith the likelihood that changes in global climate will adversely affect the soil C reservoir in the northern circumpolar permafrost zone, an understanding of the potential role of diazotrophic communities in enhancing biological N2fixation, which constrains both plant production and microbial decomposition in tundra soils, is important in elucidating the responses of soil microbial communities to global climate change. A recent study showed that the composition of the diazotrophic community in a tundra soil exhibited no change under a short-term (1.5-year) winter warming experiment. However, it remains crucial to examine whether the lack of diazotrophic community responses to warming is persistent over a longer time period as a possibly important mechanism in stabilizing tundra soil C. Through a detailed characterization of the effects of winter warming on diazotrophic communities, we showed that a long-term (5-year) winter warming substantially enhanced diazotrophic abundance and altered community composition, though soil depth had a stronger influence on diazotrophic community composition than warming. These changes were best explained by changes in soil moisture, soil thaw duration, and plant biomass. These results provide crucial insights into the potential factors that may impact future C and N availability in tundra regions.

scholarly journals Protein and Carbohydrate Fractions in Warm-Season Pastures: Effects of Nitrogen Management Strategies

Agronomy ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 847
Author(s):  
Andressa S. Berça ◽  
Abmael da S. Cardoso ◽  
Vanessa Z. Longhini ◽  
Luís O. Tedeschi ◽  
Robert Michael Boddey ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Nitrogen Fertilization ◽  
Accumulation Rate ◽  
Management Strategies ◽  
N Fertilization ◽  
Neutral Detergent Fiber ◽  
Source Control ◽  
True Protein ◽  
N Management ◽  
The Impact

Nitrogen (N) management affects herbage production and chemical composition; however, information on the impact of tropical herbage on N and carbohydrate fractions is scarce. A two-year study was conducted to investigate the potential use of pintoi peanut (Arachis pintoi) compared with N fertilization of palisade grass (Brachiariabrizantha cv. Marandu) by evaluating the herbage chemical composition (fractionation of protein and carbohydrate), herbage mass and accumulation rate, herbage disappearance rate, and stocking rate of pastures. The experiment was conducted in a completely randomized design with three treatments, and four replications (paddocks) were used with twenty-one non-lactating crossbred dairy heifers. Treatments consisted of pastures of palisade grass without a N source (control), fertilized with urea (150 kg/ha/year; fertilized), or mixed with pintoi peanut (mixed). Inclusion of the legume increased concentrations of fractions A (p = 0.009), which is the soluble N compound, and B3 (p < 0.001), which is slowly degraded true protein, compared with pastures fertilized with N and non-fertilized pastures. Nitrogen fertilization increased fraction B1 + B2 (p = 0.046), mainly true proteins, and decreased fraction C (p = 0.0007), indigestible protein, and neutral detergent fiber concentrations (p = 0.0003), contributing to increasing the nutritive value of the herbage. Additionally, N fertilization increased herbage mass (p = 0.004) and herbage allowance (p = 0.0001). Both N fertilization and biologically fixed N increased herbage allowance (p = 0.02) and accumulation rate (p = 0.02), as well as the crude protein content of herbage (p < 0.0001) compared with non-fertilized pastures. Nitrogen fertilization increased true protein and decreased indigestible protein of herbage and promoted a greater herbage mass production, while the inclusion of legumes increased soluble protein and decreased the slowly degraded true protein of herbage. Both N management strategies increased herbage allowance and accumulation rate.

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