Nitrogen in temperate crop and pasture plants

1975 ◽  
Vol 26 (1) ◽  
pp. 103 ◽  
Author(s):  
JS Gladstones ◽  
JF Loneragan
Keyword(s):  
Nitrogen Concentration ◽  
Trifolium Subterraneum ◽  
Lolium Rigidum ◽  
High Nitrogen ◽  
Pasture Legumes ◽  
Ornithopus Compressus ◽  
Nitrogen Concentrations ◽  
Three Stages ◽  
Erodium Botrys ◽  
Pasture Plants

Nitrogen concentrations were determined in the tops of 24 annual crop and pasture varieties grown together in ungrazed plots on a lateritic gravelly sand at Gidgegannup, W.A., and sampled at three stages during growth and at maturity. All legumes had higher nitrogen concentrations in the tops than all non-legumes, but considerable variation was evident within each group. Among pasture legumes, Ornithopus compressus and O. sativus had the highest concentrations, especially towards maturity, and Trifolium subterraneum cv. Yarloop and Clare the lowest. Nitrogen concentrations in all Lupinus spp. fell rapidly towards maturity, and they were unique in suffering substantial net nitrogen losses from the tops. The herb Erodium botrys grew better and took up more nitrogen under conditions of deficiency than did the grasses. Its nitrogen concentration was nevertheless very low. Among the grasses, Bromus rigidus consistently had the highest nitrogen concentration and Lolium rigidum the lowest. There was some evidence among non-legumes of a correlation between high nitrogen concentrations and/or total uptake and observed adaptation to sandy soils. The superior adaptation of legumes in the experimental environment was demonstrated. It is suggested that crop legumes could make a more important agronomic contribution than hitherto in this and similar environments.

Seasonal fluctuations in river bacteria as measured by multivariate statistical analysis of continuous cultures

1982 ◽  
Vol 28 (8) ◽  
pp. 959-975 ◽  
Author(s):  
Colin R. Bell ◽  
Maxine A. Holder-Franklin ◽  
Mervyn Franklin
Keyword(s):  
Statistical Analysis ◽  
Continuous Culture ◽  
Culture Medium ◽  
Nitrogen Concentration ◽  
Diversity Analysis ◽  
Seasonal Fluctuations ◽  
High Nitrogen ◽  
Continuous Cultures ◽  
Multivariate Statistical ◽  
Nitrogen Concentrations

Forty-eight continuous culture enrichments were performed on summer and winter water samples from two contrasting rivers. The cell output from each chemostat was dependant on the temperature and nitrogen concentration of each enrichment. The diversity of the populations from the continuous cultures, as assessed by species diversity analysis, was always greater than populations obtained on agar plates. However, the species isolated exclusively by continuous culture in these experiments were not unique to the chemostat. All of these species had been isolated at some time on plates directly. High nitrogen concentrations were found to decrease diversity. Populations sampled during the winter were influenced primarily by the concentration of nitrogen. Summer isolates were affected mainly by the temperature of the culture medium. The nutritional versatility of the population was not affected by enrichment of the continuous culture.

Growth and ignitability of annual pastures in a Mediterranean environment. 2. Ignitability of swards of various annual species

1970 ◽  
Vol 10 (42) ◽  
pp. 76 ◽  
Author(s):  
RT Parrott ◽  
CM Donald
Keyword(s):  
Soil Surface ◽  
Trifolium Subterraneum ◽  
Individual Species ◽  
Atmospheric Conditions ◽  
Annual Species ◽  
Lolium Rigidum ◽  
Mediterranean Environment ◽  
Desiccation Process ◽  
Hordeum Leporinum ◽  
Pasture Plants

A study was conducted at Adelaide of the ignitability of monospecific swards of four Mediterranean annual pasture plants under windless conditions throughout the normal field desiccation of the swards in the spring. For any individual species the ignitability depended almost wholly on the percentage of water or the very closely correlated percentage of dead herbage. Atmospheric conditions had no measurable influence on ignitability during desiccation. Trifolium subterraneum was much less ignitable at any particular level of moisture content than were the grasses. Lolium rigidum was more inflammable early in the desiccation process than was Hordeum leporinum of equal water content, presumably due to the greater continuity of dry leaf; but H. leporinum was ignitable much earlier in the spring because it matured and dried sooner than did L. rigidum. In the case of the grasses, only those firebrands that fell to or near the soil surface started a fire, whereas the more compact sward of T. subterraneum, when sufficiently dry, lit readily at the upper surface.

Effect of grazing intensity and number of grazings on herbage production and seed yields of Trifolium subterraneum, Medicago murex, and Ornithopus compressus

1994 ◽  
Vol 34 (2) ◽  
pp. 181 ◽  
Author(s):  
DJ Conlan ◽  
BS Dear ◽  
NE Coombes
Keyword(s):  
Seed Production ◽  
Seed Yield ◽  
Grazing Intensity ◽  
Trifolium Subterraneum ◽  
Grazing Pressure ◽  
Early Spring ◽  
Pasture Legumes ◽  
Heavy Grazing ◽  
Ornithopus Compressus ◽  
The Impact

The impact of grazing intensity and number of grazings was assessed on the growth and seed production of 5 annual pasture legumes [Trifoliunz subterraneum var. subterraneum cv. Karridale, var. brachycalycinum cv. Clare, var. yanninicum cv. Trikkala; Medicago murex (murex medic) cv. Zodiac; Ornithopus compressus L. (yellow serradella) cv. Avila]. There were 7 grazing treatments: an ungrazed control; and 2 grazing intensities (light and heavy), each for 3 periods of grazing (winter, winter-early spring, winter-late spring). Tethered sheep in small experimental plots were used to provide controlled herbage removal across all cultivars through winter and winter-spring grazing. This grazing system resulted in significantly different levels of herbage being present in the light and heavy grazing treatments following each grazing period. Grazing had variable effects on seed production: <35% increase for Trikkala, and no significant effect for Karridale. Both cultivars continued growth and seed production late in the season after grazing pressure was removed on 8 November. Seed yield of Clare was reduced by 46-49% by heavy grazing treatments. Seed yield of murex medic was not significantly affected by grazing, while that of serradella was reduced by 30-55% by grazing late in the season. The seed yield responses show that cultivar and species responses to grazing may be highly variable. Under favourable spring conditions, Trikkala, Karridale, and murex medic can be grazed heavily until late in the season without adversely affecting seed yield, whilst Clare and Avila cannot.

A Quantitative Study of the Spores and Anatomy of Mycorrhizas Formed by a Species of Glomus, With Reference to Its Taxonomy

1979 ◽  
Vol 27 (4) ◽  
pp. 363 ◽  
Author(s):  
LK Abbott ◽  
AD Robson
Keyword(s):  
Size Range ◽  
Trifolium Subterraneum ◽  
Arbuscular Mycorrhizas ◽  
Nitrogen Supply ◽  
Lolium Rigidum ◽  
Anatomical Characteristics ◽  
Vesicular Arbuscular ◽  
Identification Of Species ◽  
The Relationship ◽  
Erodium Botrys

The development of spores and sporocarps was studied in two isolates of a species of Glomus collected in Western Australia. The isolates, which had been maintained in pot culture, differed slightly in the size range of spores and in the relationship between spore size and the development of the peridium. Anatomical characteristics of mycorrhizas of three pasture species (Trifolium subterraneum, Erodium botrys and Lolium rigidum) formed with this species of Glomus were essentially the same and were largely unaffected by nitrogen supply. The hyphae in nitrogen-deficient plants were slightly wider than those in nitrogen-adequate plants of T. subterraneum and E. botrys. The effect of phosphorus supply on the anatomy of mycorrhizas formed by this fungus and T. subterraneum was studied with time. Phosphorus supply had no effect on the formation of arbuscles, the density of hyphae within infected roots, or the morphology of the branching pattern of the endophyte hyphae within the root. However, phosphate added above that required for maximum plant yield eliminated vesicle formation. Anatomical characteristics of the mycorrhizas changed little with time except for arbuscle number, which decreased markedly between 29 and 50 days after sowing. We concluded that the anatomy of vesicular arbuscular mycorrhizas formed by a particular endophyte species grown under a range of conditions may not be as variable as has been generally assumed. There is scope for identification of species of endophyte within plant roots. Furthermore, some features of infection morphology could prove to be useful for taxonomic purposes.

Field responses to cobalt and molybdenum by different legume species, with inferences on the role of cobalt in legume growth

1977 ◽  
Vol 28 (4) ◽  
pp. 619 ◽  
Author(s):  
JS Gladstones ◽  
JF Loneragan ◽  
NA Goodchild
Keyword(s):  
Nitrogen Concentration ◽  
Haemoglobin Concentration ◽  
Trifolium Subterraneum ◽  
Lupinus Luteus ◽  
Lateritic Soil ◽  
Legume Species ◽  
Molybdenum Addition ◽  
Nitrogen Concentrations ◽  
Yield Responses

Six legume species were sown over two seasons on a sandy lateritic soil of marginal cobalt and molybdenum status, with varying rates and combinations of applied cobalt and molybdenum. The seeds were from plants previously grown on the same soil without cobalt or molybdenum addition. Species differed in their responses. Lupinus angustifolius responded strongly to cobalt, which increased dry matter yield by nearly 50%, but at most only marginally to molybdenum. Lupinus cosentinii, Vicia atropurpurea and Trifolium subterraneum responded to molybdenum but not to cobalt. Lupinus luteus, and more doubtfully Trifolium hirtum, responded to neither element. Yield responses to molybdenum were always accompanied by increased nitrogen concentrations in the tops. Cobalt application resulted in either no change or a reduction ir, nitrogen concentration in the tops, even when yield was increased. No interaction was evident between the two elements. Neither element increased nodule numbers, which were ample in all treatments, but in L. angustfolius cobalt markedly increased both nodule size and to a lesser extent crown nodule incidence and slightly increased leg-haemoglobin concentration. Possible reasons are discussed for the unexpectedly unchanged or reduced nitrogen concentrations in the tops of L. angustifolius showing yield responses to cobalt. One suggestion is that enhanced rhizobium and nodule growth resulted in greater cytokinin production, with a greater effect on top growth under the conditions of the experiments than that stemming from increased nitrogen fixation.

Effects of subterranean, rose and cupped clovers on soil nitrogen and on a subsequent cereal crop

1980 ◽  
Vol 20 (104) ◽  
pp. 354 ◽  
Author(s):  
ER Watson ◽  
P Lapins ◽  
RJW Barron
Keyword(s):  
Soil Nitrogen ◽  
Nitrogen Uptake ◽  
Dry Matter ◽  
Inorganic Nitrogen ◽  
Nitrogen Concentration ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Wheat Crop ◽  
Cereal Crop ◽  
Nitrogen Concentrations

Three annual clover species : subterranean clover, Trifolium subterraneum (cv. Geraldton), rose clover, T. hirtum (cv. Kondinin), and cupped clover, T. cherleri (cv. Yamina) were compared for yield of dry matter, for their effects on soil nitrogen, dry matter yield, and nitrogen uptake by a subsequent cereal crop. In one experiment, the three clover species and annual ryegrass (Lolium rigidum), were grown in lysimeters to provide measurements of dry matter and nitrogen yields of plant tops and roots. Half of the lysimeters, from which the plant roots had not been removed, were later sown with wheat. Rose clover produced the highest yield of root nitrogen, and this was reflected in higher nitrogen uptake in the succeeding wheat crop. Nitrogen yield of wheat after ryegrass was 60% of the average yield after clovers. The three clover species were also included in a pasture experiment, which was grazed by sheep for five years. Samples were taken from the field plots to provide soil for a glasshouse pot experiment, and for chemical analysis. In the pasture experiment, build up of soil nitrogen over six years did not differ significantly between the subterranean and rose clover treatments, although there were large differences in clover plant numbers and herbage production, and botanical composition of the pastures. However, inorganic nitrogen concentrations were much higher in soil from the subterranean clover plots than in soil from the rose or cupped clover plots, particularly in the later stages of the field experiment. Total nitrogen increase and mineral nitrogen concentration were lowest in soil from the cupped clover plots, although herbage yield was comparable with that of rose clover

Infection studies with Cercospora zebrina on pasture legumes in Western Australia

1985 ◽  
Vol 25 (4) ◽  
pp. 850 ◽  
Author(s):  
MJ Barbetti
Keyword(s):  
Medicago Sativa ◽  
Western Australia ◽  
White Clover ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Disease Development ◽  
High Humidity ◽  
Inoculum Level ◽  
Pasture Legumes ◽  
Ornithopus Compressus

The effects of inoculum level, and temperature and humidity regimes on the development of Cercospora blackstem disease (caused by Cercospora zebrina) in subterranean clover (Trifolium subterraneum) were investigated. Mycelial fragments were an effective and reliable inoculum. The incidence, severity, and the rate of disease development increased with increasing period of high humidity after inoculation and with increasing concentrations of inoculum. Disease was greatest at 18/13� (12/12 h, day/ night), followed by 21/16�C, and then l5/10�C While all cultivars of T. subterraneum sprayed with hyphal fragments of C. zebrina became infected, Trikkala and Larisa showed some resistance. Of the alternative pasture legumes, lucerne (Medicago sativa), medic (M. littoralis, M. truncatula), drooping-flowered clover (T. cernuum), strawberry clover (T. fragiferum), rose clover (T. hirtum) and white clover (T. repens) were all susceptible; only serradella (Ornithopus compressus) was resistant.

High Nitrogen Concentration in Fe-Cr-Ni Alloys

1991 ◽  
Vol 251 ◽  
Author(s):  
James C. Rawers ◽  
Nev A. Gokcen ◽  
Robert D. Pehlke
Keyword(s):  
High Pressure ◽  
Nitrogen Concentration ◽  
Weight Percent ◽  
Published Data ◽  
High Nitrogen ◽  
Concentration Data ◽  
Statistical Correlations ◽  
Nitrogen Concentrations ◽  
Pressure Melting ◽  
Percent Nitrogen

ABSTRACTIncreasing the nitrogen concentration in iron and iron alloys significantly improves their mechanical properties. A recent technique for melting in a hot-isostatic pressure furnace using nitrogen as the pressurizing gas has been developed by U.S. Bureau of Mines researchers for making massive nitrogen additions to iron (up to 1.6 weight percent nitrogen) and iron-chromium-nickel alloys (up to 6.6 weight percent nitrogen). The total nitrogen concentration measured at atmospheric pressure and room temperature was determined to be the equilibrium nitrogen concentration in the molten alloy. Statistical correlations were derived to explain the effects of melt pressure and alloy composition on the resulting nitrogen concentration. Nitrogen concentrations measured in solidified alloys made by high pressure melting techniques at lower pressures are consistent with previous published data. Computer generated phase diagrams for high nitrogen-chromium concentrations are also consistent with nitride microstructure observed after high-pressure melting. Extension of existing atmospheric nitrogen concentration data to higher pressure nitrogen concentrations shows Sievert's law (nitrogen concentration is proportional to the square root of the nitrogen melt pressure) to be valid for pure iron. However, substantial deviations from Sievert's law are observed for higher alloy compositions. Statistical fits of thermodynamic concentration data to the high-pressure melt nitrogen data requires evaluating element concentration terms, interaction effect terms, pressure terms, and pressure-composition effects terms. Examination of the nitrogen concentration data suggests several methods of correlation.

Selection by grazing sheep of pasture plants at low herbage availability and responses of the plants to grazing

1986 ◽  
Vol 37 (5) ◽  
pp. 527 ◽  
Author(s):  
DM Broom ◽  
GW Arnold
Keyword(s):  
Dry Matter ◽  
Growth Form ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Growing Season ◽  
Abundant Species ◽  
Ecological Implications ◽  
Wimmera Ryegrass ◽  
Erodium Botrys ◽  
Pasture Plants

Merino sheep grazing annual pasture at the beginning of the growing season when the amount of herbage on offer was small, preferred to graze Wimmera ryegrass Lolium rigidum or subterranean clover Trifolium subterraneum rather than capeweed Arctotheca calendula, and Erodium botrys was avoided completely. Behaviour observations showed that capeweed plants were usually avoided. When the plants were grasped they were sometimes pulled up by the roots and then dropped so that the number of capeweed plants in the pasture declined. Supplementation with oats reduced grass intake. Harvesting behaviour changed with pasture conditions: as grass height declined in the pasture, the rates of biting, stepping and head swinging increased. Pasture measurements showed that, whilst capeweed plants continued to increase in height during grazing, as did ungrazed controls, ryegrass and clover plants decreased or remained short. Herbage dry matter increased in all species, owing especially to basal growth. The proportion of shoots and petioles which were erect increased in ungrazed plants, but the proportion which were prostrate was much greater in grazed plants. Individual plants adapted their growth form in a way which counteracted the depredations of grazers. The ecological implications of these findings are important. Firstly, the sheep were not foraging optimally in terms of maximising rate of intake, since two abundant species were largely ignored even though food availability was low. Secondly, because of their selectivity the sheep were giving the capeweed and Erodium a competitive advantage which, in these pastures, will persist through the growing season.

Nitrogen cycling in a Venezuelan tropical seasonally flooded forest: soil nitrogen mineralization and nitrification

1994 ◽  
Vol 10 (3) ◽  
pp. 399-416 ◽  
Author(s):  
Barrios E. ◽  
Herrera R.
Keyword(s):  
Soil Nitrogen ◽  
Nitrogen Availability ◽  
Inorganic Nitrogen ◽  
Nitrogen Concentration ◽  
Ammonium Nitrogen ◽  
Wet Season ◽  
Flooded Forest ◽  
Nitrogen Concentrations ◽  
Minimum Stress ◽  
Seasonally Flooded

ABSTRACTSeasonally flooded forests represent a transition between terrestrial and aquatic ecosystems. The Mapire river, a tributary of the Orinoco river, floods its surrounding forests during the wet season (May–December). The soils are very acid and the total nitrogen concentration (0.1%) is only half that found in nearby soils flooded by Orinoco waters. Ammonium-nitrogen predominates in the soil during the flooded period while nitrate-nitrogen concentrations are higher in the dry period. Wide fluctuations in the inorganic nitrogen fractions did not considerably affect the annual course of soil nitrogen.The predominance of mineralization versus nitrification (56 and 5 μgsoil month−1respectively) and possibly the synchronization of nitrogen availability with plant demand could be considered as nitrogen conserving mechanisms.In synchrony with the hydrologic cycle, the seasonally flooded forest studied shows a nitrogencycle where inputs and accumulation are maximized when the system is under minimum stress (dry season). During flooding, the system enters a period of dormancy making minimal use of nutrient and energy to avoid or tolerate anaerobiosis.

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