Intercropping affects genetic potential for inorganic nitrogen cycling by root-associated microorganisms in Medicago sativa and Dactylis glomerata

2017 ◽  
Vol 119 ◽  
pp. 260-266 ◽  
Author(s):  
Ming Zhao ◽  
Christopher M. Jones ◽  
Johan Meijer ◽  
Per-Olof Lundquist ◽  
Petra Fransson ◽  
...  
Keyword(s):  
Medicago Sativa ◽  
Nitrogen Cycling ◽  
Inorganic Nitrogen ◽  
Dactylis Glomerata ◽  
Genetic Potential

NITROGENASE ACTIVITY OF ALFALFA GROWN ALONE AND IN MIXTURE WITH GRASS UNDER GREENHOUSE CONDITIONS

1985 ◽  
Vol 65 (3) ◽  
pp. 787-791
Author(s):  
H. A. BURITY ◽  
B. E. COULMAN ◽  
M. A. FARIS
Keyword(s):  
Medicago Sativa ◽  
Nitrogenase Activity ◽  
Dactylis Glomerata ◽  
Phleum Pratense ◽  
Bromus Inermis ◽  
Smooth Bromegrass ◽  
Medicago Sativa L ◽  
Dactylis Glomerata L ◽  
Phleum Pratense L ◽  
Nodule Tissue

A greenhouse experiment has shown that total nitrogenase activity of alfalfa (Medicago sativa L.) is not significantly affected when grown in association with timothy (Phleum pratense L.), smooth bromegrass (Bromus inermis Leyss) or orchardgrass (Dactylis glomerata L.) except after initial harvest when decreased alfalfa activity was associated with smooth bromegrass or orchardgrass. It was concluded that mixed cultures of alfalfa with timothy, smooth bromegrass or orchardgrass have no effect on alfalfa N2 fixation. The results also suggest the occurrence of N transference from alfalfa to associated grasses. It is speculated that this transfer is not primarily due to the death of roots and nodule tissue (after harvest), but involves some degree of N excretion during the period before initial harvest.Key words: Alfalfa-grass mixtures, N2-fixation, nodule activity, N-transference

scholarly journals 92 Brix as an Indicator of Energy Value in Alfalfa and Orchardgrass Herbage

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 77-77
Author(s):  
Kathy J Soder ◽  
Eric D Billman ◽  
Jeff Horst ◽  
Kristi Balk ◽  
Aimee Hafla
Keyword(s):  
Medicago Sativa ◽  
Nutritive Value ◽  
Dactylis Glomerata ◽  
Total Dissolved Solids ◽  
Dissolved Solids ◽  
Total Sugars ◽  
Energy Value ◽  
Freeze Dried ◽  
Forage Species ◽  
Wet Lab

Abstract This study correlated Brix values (measure of total dissolved solids via refractometer) with wet-lab analyses (WLA) of sugar concentrations in fresh herbage of two forage species, alfalfa (ALF; Medicago sativa) and orchardgrass (ORG; Dactylis glomerata) to estimate energy value of pastures. Four monthly samplings occurred from May-August, 2019. At each sampling, eight ALF and ORG samples were collected from established monocultures of each species. Solubles were extracted from fresh herbage using a hand-held garlic press. Triplicate Brix readings were recorded per sample using a digital refractometer. Fresh herbage samples were flash-frozen in liquid N, freeze-dried, and analyzed via WLA for total and individual (glucose and fructose) sugar concentrations, as well as nutritive value (CP, NDF, and ADF; Agri-King, Inc., Fulton, IL). The TDN, RFV, and RFQ were calculated. Brix values were correlated with WLA using the PROC CORR procedure in SAS, with significance established at P < 0.05 and trends at 0.05 < P < 0.10. Brix values were negatively correlated (P < 0.001) with WLA of total sugars (-0.65), glucose (-0.6), and fructose (-0.68) in ORG while no significant correlations (P > 0.10) were detected in ALF. Conversely, Brix values of ORG and ALF were positively correlated (P < 0.01) with NDF (0.57 – 0.58) and hemicellulose (0.42 – 0.55), as well as with ADF in ALF (0.54). Brix was negatively correlated (P < 0.05) with CP in ALF (-0.41), but there was no correlation (P > 0.10) with ORG. No correlations (P > 0.10) were detected between Brix and TDN, RFV, and RFQ. These results indicate that the Brix index does not directly translate to forage quality, particularly sugar concentrations, of ALF and ORG, and may inadvertently select herbage with increased fiber concentrations. Producers should consider more accurate methods, such as WLA, for assessing energy value of pastures.

scholarly journals Changes of Soil Microbes Related with Carbon and Nitrogen Cycling after Long-Term CO2 Enrichment in a Typical Chinese Maize Field

2020 ◽  
Vol 12 (3) ◽  
pp. 1250 ◽  
Author(s):  
Tiantian Diao ◽  
Zhengping Peng ◽  
Xiaoguang Niu ◽  
Rongquan Yang ◽  
Fen Ma ◽  
...  
Keyword(s):  
16S Rrna ◽  
Nitrogen Cycling ◽  
Relative Abundance ◽  
Soil Microbes ◽  
Inorganic Nitrogen ◽  
Ammonia Oxidizing Bacteria ◽  
Rhizospheric Soil ◽  
Carbon And Nitrogen ◽  
Carbon And Nitrogen Cycling ◽  
Maize Field

Elevated atmospheric CO2 concentration (eCO2) has been the most important driving factor and characteristic of climate change. To clarify the effects of eCO2 on the soil microbes and on the concurrent status of soil carbon and nitrogen, an experiment was conducted in a typical summer maize field based on a 10-year mini FACE (Free Air Carbon Dioxide Enrichment) system in North China. Both rhizospheric and bulk soils were collected for measurement. The soil microbial carbon (MBC), nitrogen (MBN), and soil mineral N were measured at two stages. Characteristics of microbes were assayed for both rhizospheric soil and bulk soils at the key stage. We examined the plasmid copy numbers, diversities, and community structures of bacteria (in terms of 16s rRNA), fungi (in terms of ITS-internal transcribed spacer), ammonia oxidizing bacteria (AOB) and denitrifiers including nirK, nirS, and nosZ using the Miseq sequencing technique. Results showed that under eCO2 conditions, both MBC and MBN in rhizospheric soil were increased significantly. The quantity of ITS was increased in the eCO2 treatment compared with that in the ambient CO2 (aCO2) treatment, while the quantity of 16s rRNA in rhizospheric soil showed decrease in the rhizospheric soil in the eCO2 treatment. ECO2 changed the relative abundance of microbes in terms of compositional proportion of some orders or genera particularly in the rhizospheric soil-n particular, Chaetomium increased for ITS, Subgroups 4 and 6 increased for 16s rRNA, Nitrosospira decreased for AOB, and some genera showed increase for nirS, nirK, and nosZ. Nitrate N was the main inorganic nitrogen form at the tasseling stage and both quantities of AOB and denitrifiers, as well as the nosZ/(nirS+nirK) showed an increase under eCO2 conditions particularly in the rhizospheric soil. The Nitrosospira decreased in abundance under eCO2 conditions in the rhizospheric soil and some genera of denitrifiers also showed differences in abundance. ECO2 did not change the diversities of microbes significantly. In general, results suggested that 10 years of eCO2 did affect the active component of C and N pools (such as MBC and MBN) and both the quantities and relative abundance of microbes which are involved in carbon and nitrogen cycling, possibly due to the differences in both the quantities and component of substrate for relevant microbes in the rhizospheric soils.

Msma and Dsma for Removing Grass Weeds From Grass-Legume Seedlings

Weed Science ◽  
1974 ◽  
Vol 22 (6) ◽  
pp. 578-583
Author(s):  
E. J. Peters ◽  
S. A. Lowance
Keyword(s):  
Medicago Sativa ◽  
Weed Control ◽  
Butyric Acid ◽  
Dactylis Glomerata ◽  
Birdsfoot Trefoil ◽  
Digitaria Sanguinalis ◽  
Reed Canarygrass ◽  
Elemental Arsenic ◽  
Panicum Dichotomiflorum ◽  
Forage Mixtures

MSMA (monosodium methanearsonate) and DSMA (disodium methanearsonate) were applied to seedling orchardgrass (Dactylis glomerata L.) – alfalfa (Medicago sativa L. ‘WL-304′) and reed canarygrass (Phalaris arundinacea L. ‘Ioreed’)-birdsfoot trefoil (Lotus corniculatus L. ‘Dawn’) mixtures before grasses were beyond the three-leaf stage. MSMA and DSMA controlled foxtails (Setaria spp.), large crabgrass [Digitaria sanguinalis (L.) Scop.] and fall panicum (Panicum dichotomiflorum Michx.), but were not effective on barnyardgrass [Echinochloa crus-galli (L.) Beauv.]. The addition of 2,4-DB [4-(2,4-dichlorophenoxy)butyric acid] or bromoxynil (3,5-dibromo-4-hydroxybenzonitrile) to MSMA or DSMA increased broadleaf weed control over that obtained with MSMA or DSMA alone. The forage mixtures tolerated 2 to 3 kg/ha of MSMA or DSMA and increased in yield when weeds were controlled. Elemental arsenic found in the forage increased in forage as the rates of MSMA or DSMA increased. Eighty-six to 96% less arsenic was found in early-than in late-treated forage.

scholarly journals Photoproduction of ammonium in the Southeastern Beaufort Sea and its biogeochemical implications

2012 ◽  
Vol 9 (4) ◽  
pp. 4441-4482 ◽  
Author(s):  
H. Xie ◽  
S. Bélanger ◽  
G. Song ◽  
R. Benner ◽  
A. Taalba ◽  
...  
Keyword(s):  
Nitrogen Cycling ◽  
Dissolved Organic Nitrogen ◽  
Organic Nitrogen ◽  
Inorganic Nitrogen ◽  
River Estuary ◽  
Beaufort Sea ◽  
Canada Basin ◽  
Molar Ratio ◽  
Entire Study ◽  
Mackenzie River

Abstract. Photochemistry of dissolved organic matter (DOM) plays an important role in marine biogeochemical cycles, including the regeneration of inorganic nutrients. DOM photochemistry affects nitrogen cycling by converting bio-refractory dissolved organic nitrogen to labile inorganic nitrogen, mainly ammonium (NH4+). During the August 2009 Mackenzie Light and Carbon (MALINA) Program, the absorbed photon-based efficiency spectra of NH4+ photoproduction (i.e. photoammonification) were determined using water samples from the SE Beaufort Sea, including the Mackenzie River estuary, shelf, and Canada Basin. The photoammonification efficiency decreased with increasing wavelength across the ultraviolet and visible regimes and was higher in offshore waters than in shelf and estuarine waters. The efficiency was positively correlated with the molar nitrogen : carbon ratio of DOM and negatively correlated with the absorption coefficient of chromophoric DOM (CDOM). Combined with collateral measurements of CO2 and CO photoproduction, this study revealed a stoichiometry of DOM photochemistry with a CO2:CO:NH4+ molar ratio of 165:11:1 in the estuary, 60:3:1 on the shelf, and 18:2:1 in the Canada Basin. The NH4+ efficiency spectra, along with solar photon fluxes, CDOM absorption coefficients and sea ice concentrations, were used to model the monthly surface and depth-integrated photoammonification rates in 2009. The summertime (June–August) rates at the surface reached 6.6 nmol l−1 d−1 on the Mackenzie Shelf and 3.7 nmol l−1 d−1 further offshore; the depth-integrated rates were correspondingly 8.8 μmol m−2 d−1 and 11.3 μmol m−2 d−1. The offshore depth-integrated rate in August (8.0 μmol m−2 d−1) was comparable to the missing dissolved inorganic nitrogen (DIN) source required to support the observed primary production in the upper 10-m layer of that area. The yearly NH4+ photoproduction in the entire study area was estimated to be 1.4 × 108 moles, with 85 % of it being generated in summer when riverine DIN input is low. Photoammonification could mineralize 4 % of the annual dissolved organic nitrogen (DON) exported from the Mackenzie River and provide a~DIN source corresponding to 7 % of the riverine DIN discharge and 1400 times the riverine NH4+ flux. Under a climate warming-induced ice-free scenario, these quantities would increase correspondingly to 6 %, 11 %, and 2100 times. Photoammonification is thus a significant nitrogen cycling term and may fuel previously unrecognized autotrophic and heterotrophic production pathways in the surface SE Beaufort Sea.

scholarly journals Microbial nitrogen cycling on the Greenland Ice Sheet

2011 ◽  
Vol 8 (5) ◽  
pp. 10423-10457 ◽  
Author(s):  
J. Telling ◽  
M. Stibal ◽  
A. M. Anesio ◽  
M. Tranter ◽  
I. Nias ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogen Cycling ◽  
Microbial Growth ◽  
Inorganic Nitrogen ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Available Nitrogen ◽  
Microbial Nitrogen ◽  
Nitrogen Demand

Abstract. Microbial nitrogen cycling was investigated along a 79 km transect into the Greenland Ice Sheet (GrIS) in early August 2010. The depletion of dissolved nitrate and production of ammonium (relative to icemelt) in cryoconite holes within 7.5 km of the ice sheet margin suggested microbial uptake and ammonification respectively. Nitrogen fixation (<4.2 μmoles C2H4 m−2 day−1 to 16.3 μmoles C2H4 m−2 day−1) was active in some cryoconite holes at sites up to 5.7 km from the ice sheet margin, with nitrogen fixation inversely correlated to concentrations of inorganic nitrogen. There may be the potential for the zone of nitrogen fixation to progressively extend further into the interior of the GrIS as the melt season progresses as reserves of available nitrogen are depleted. Estimated annual inputs of nitrogen from nitrogen fixation along the transect were at least two orders of magnitude lower than inputs from precipitation, with the exception of a 100 m long marginal debris-rich zone where nitrogen fixation could potentially equal or exceed that of precipitation. The average estimated contribution of nitrogen fixation to the nitrogen demand of net microbial growth at sites along the transect ranged from 0% to 17.5%.

scholarly journals Dynamic seasonal nitrogen cycling in response to anthropogenic N-loading in a tropical catchment, Athi–Galana–Sabaki River, Kenya

2013 ◽  
Vol 10 (5) ◽  
pp. 8637-8683
Author(s):  
T. R. Marwick ◽  
F. Tamooh ◽  
B. Ogwoka ◽  
C. Teodoru ◽  
A. V. Borges ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Stable Isotope ◽  
Nitrogen Cycling ◽  
Residence Time ◽  
Inorganic Nitrogen ◽  
Dry Season ◽  
N Cycling ◽  
Cyanobacterial Blooms ◽  
Data Set ◽  
Rain Season

Abstract. As part of a broader study on the riverine biogeochemistry in the Athi–Galana–Sabaki (A–G–S) River catchment (Kenya), we present data constraining the sources, transit and transformation of multiple nitrogen (N) species as they flow through the A–G–S catchment (~47 000 km2). The data-set was obtained in August–September 2011, November 2011, and April–May 2012, covering the dry season, short-rain season and long-rain season respectively. Release of, largely untreated, waste water from the city of Nairobi had a profound impact on the biogeochemistry of the upper Athi river, leading to low dissolved oxygen (DO) saturation levels (67–36%), high ammonium (NH4+) concentrations (1193–123 μmol L−1), and high dissolved methane (CH4) concentrations (6729–3765 nmol L−1). Total dissolved inorganic nitrogen (DIN) concentrations entering the study area were highest during the dry season (1195 μmol L−1), while total DIN concentration was an order of magnitude lower during the short and long rain seasons (212 and 193 μmol L−1, respectively). During the rain seasons, low water residence time led to relatively minimal instream N-cycling prior to discharge to the ocean. Conversely, increased residence time during the dry season creates two differences comparative to wet season conditions, where (1) intense cycling and removal of DIN in the upper- to mid-catchment leads to significantly less DIN export during the dry season, and (2) as a result of the intense DIN cycling, dry season particulate N export is significantly enriched in the N stable isotope ratio (δ15NPN), strongly reflecting the dominance of organic matter as the prevailing source of riverine nitrogen. The rapid removal of NH4+ in the upper study area during the dry season was accompanied by a quantitatively similar production of NO3− and nitrous oxide (N2O) downstream, pointing towards strong nitrification over this reach during the dry season. Nitrous oxide produced was rapidly degassed downstream, while the elevated NO3− concentrations steadily decreased to levels observed elsewhere in more pristine African river networks. Low pelagic primary production rates over the same reach suggest that benthic denitrification was the dominant process controlling the removal of NO3−, although large cyanobacterial blooms further downstream highlight the significant role of DIN assimilation by primary producers in the drainage network. The intense upper- to mid-catchment N-cycling leads to a significantly enriched δ15NPN during the dry season (mean: +16.5 ± 8.2‰ but reaching as high as +31.5‰) compared to the short (+7.3 ± 2.6‰) and long (+7.6 ± 5.9‰) rain seasons. A strong correlation found between seasonal δ15NPN and oxygen stable isotope ratios (δ18OH2O; as a proxy of freshwater discharge) presents the possibility of employing a combination of proxies, such as δ15NPN of sediments, bivalves and near-shore corals, to reconstruct how historical land-use changes have influenced nitrogen cycling within the catchment, whilst potentially providing foresight in the impacts of future land management decisions.

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