Estimates of seasonal nitrogen fixation of annual subterranean clover-based pastures using the15N natural abundance technique

1995 ◽  
Vol 175 (1) ◽  
pp. 57-66 ◽  
Author(s):  
T. P. Bolger ◽  
J. S. Pate ◽  
M. J. Unkovich ◽  
N. C. Turner
Keyword(s):  
Nitrogen Fixation ◽  
Subterranean Clover ◽  
Natural Abundance

An evaluation of 15N methods for estimating nitrogen fixation in a subterranean clover-perennial ryegrass sward

1983 ◽  
Vol 34 (4) ◽  
pp. 391 ◽  
Author(s):  
FJ Bergersen ◽  
GL Turner
Keyword(s):  
Nitrogen Fixation ◽  
Perennial Ryegrass ◽  
N2 Fixation ◽  
Slow Growth ◽  
Subterranean Clover ◽  
Natural Abundance ◽  
Nitrogen Accumulation ◽  
Plant Parts ◽  
Natural Enrichment

Nitrogen (N2) fixation by nodulated subterranean clover, in swards with perennial ryegrass, was studied by using the natural abundance of 15N in sward components compared with a method using artificial enrichment of the soil with small amounts of K15NO3. Significant differences between the 15N concentrations in ryegrass and clover enabled yield-independent estimates of the proportion (P) of clover nitrogen fixed from atmospheric N2. Yield-dependent estimates of P were also made during intervals of growth in autumn and in spring. Values of P increased with time and during spring were close to l00%, when maximum fixation rates were approximately 4 kg N ha-1 day-1. Consistent differences in 15N concentration of shoots and roots had little effect on P. Early in the experiment, natural enrichment gave lower estimates of P than 15NO-3 -enriched treatments. Yield-independent and yield-dependent methods gave similar estimates of P. During winter, when no net growth or nitrogen accumulation was recorded, there appeared to be loss of 15N from the plants, possibly because of loss of highly labelled plant parts, balanced by slow growth of tissue containing a lower 15N concentration. During winter, calculation of P was therefore unreliable.

Studies of seed pelleting as an aid to legume inoculation. 5. Effects of incorporation of molybdenum compounds in the seed pellet on inoculant survival, seedling nodulation and plant growth of lucerne and subterranean clover

1980 ◽  
Vol 20 (102) ◽  
pp. 63 ◽  
Author(s):  
RR Gault ◽  
J Brockwell
Keyword(s):  
Nitrogen Fixation ◽  
Plant Growth ◽  
Nitrogen Content ◽  
Significant Relationship ◽  
Storage Time ◽  
Sodium Molybdate ◽  
Subterranean Clover ◽  
Ammonium Molybdate ◽  
Molybdic Acid ◽  
Molybdenum Disulphide

Four molybdenum compounds were mixed with lime and applied as coatings to inoculated seed of lucerne (Hunter River) and subterranean clover (Mount Barker). The seed was sown immediately in molybdenum-deficient soil in the field or stored for periods up to 84 days before sowing. As storage time lengthened, the survival of both lucerne and clover rhizobia was adversely affected by sodium molybdate but not by molybdic acid, ammonium molybdate or molybdenum disulphide. This effect was reflected in poorer nodulation in the sodium molybdate treatments. Nitrogen fixation, using foliage nitrogen content as an index, was always higher in the molybdenum treatments than in the no-molybdenum controls. Both species appeared able to extract molybdenum from molybdenum disulphide. Otherwise, there were no treatment differences in plant growth, but there was a significant relationship between the proportion of seedlings nodulated by the inoculant strains and the amount of nitrogen fixation. It is concluded that seed-applied molybdenum would benefit pasture establishment in some circumstances and would not interfere with inoculant survival or seedling nodulation provided that sodium molybdate was not used for the purpose.

Rhizosphere relationships of subterranean clover. I. Interactions between strains of Rhizobium trifolii.

1954 ◽  
Vol 5 (2) ◽  
pp. 247 ◽  
Author(s):  
JR Harris
Keyword(s):  
Nitrogen Fixation ◽  
Host Plant ◽  
Root Zone ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Rhizobium Trifolii ◽  
Rhizobial Strain ◽  
Susceptible Host ◽  
Active Elements ◽  
Indigenous Microflora

A study was made of a number of effective and ineffective strains of Rhizobium trifolii in association with subterranean clover (Trifolium subterraneum L.), variety Bacchus Marsh. Where these were inoculated singly into sterilized soils in pot experiments conducted in the greenhouse, typical effective, ineffective, or intermediate plant reactions were obtained. Where more than one strain was inoculated, competition between strains took place and was reflected in nodule pattern and plant reaction. Some strains consistently failed to produce appreciable nodules in the presence of other rhizobia, some showed modification to varying degrees, and some were unaffected. Such behaviour was found to be closely linked with the ability of the strain to proliferate in the rhizosphere of the host plant, and placement of inoculum was shown to influence plant reaction. The concept of "incursion" as a property of a rhizobial strain is suggested. An incursive strain is one able to migrate from the initial site of inoculation and establish an adequate population in the root zone of the susceptible host despite the presence of active elements of the indigenous microflora and microfauna, including antagonistic and predatory forms. The property of incursion is independent of considerations of efficiency of nitrogen fixation or virulence for the host plant. Strains of rhizobia which are poorly incursive may fail to infect the host upon which they have been inoculated if subject to competition from indigenous rhizobia already established in the soil. The necessity of assessing properties of virulence and incursion as well as efficiency of nitrogen fixation in selecting rhizobia for purposes of commercial inoculation is stressed, and the methods of making such tests are discussed.

Differences in contribution of biological nitrogen fixation to yield performance of common bean cultivars as assessed by the 15N natural abundance technique

2020 ◽  
Vol 454 (1-2) ◽  
pp. 327-341
Author(s):  
Rafael Sanches Pacheco ◽  
Robert Michael Boddey ◽  
Bruno José Rodrigues Alves ◽  
Enderson Petrônio de Brito Ferreira ◽  
Rosângela Straliotto ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Common Bean ◽  
Biological Nitrogen Fixation ◽  
15N Natural Abundance ◽  
Natural Abundance ◽  
Yield Performance ◽  
Biological Nitrogen

The cobalt requirement of subterranean clover in the field

1963 ◽  
Vol 14 (1) ◽  
pp. 39 ◽  
Author(s):  
PG Ozanne ◽  
EAN Greenwood ◽  
TC Shaw
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogen Content ◽  
Symbiotic Nitrogen Fixation ◽  
Subterranean Clover ◽  
Applied Nitrogen

Yield increases of 30% were obtained on two subterranean clover pastures in response to dressings of 2 and 10 oz CoSO4.7H2O per acre. A dressing of salts containing chromium, nickel, vanadium, tungsten, aluminium, and iodine had no effect. Applications of cobalt increased the nitrogen content of the clover in all cases. No response to cobalt was obtained in the presence of adequate applied nitrogen. Clover growth was sharply reduced when cobalt contents fell below 0.04 p.p.m. The unfertilized soils on which the experiments were located contained only 0.022 and 0.019 p.p.m. cobalt in the 0–4 in. layer. Applied cobalt was not leached downward but remained in the surface 4 in. However, less than 0.5% of the applied cobalt was taken up by the pasture. To obtain a response to applied cobalt it appears necessary for legumes to be growing in soil containing Rhizobia capable of symbiotic nitrogen fixation; but the soil must also be very low in available cobalt and nitrogen.

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