Growth and nitrogen fixation by subterranean clover in response to inoculation, molybdenum application and soil amendment with lime

1985 ◽  
Vol 17 (6) ◽  
pp. 791-796 ◽  
Author(s):  
D.R. Coventry ◽  
J.R. Hirth ◽  
T.G. Reeves ◽  
V.F. Burnett
Keyword(s):  
Nitrogen Fixation ◽  
Soil Amendment ◽  
Subterranean Clover

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.

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.

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

Effects of Nitrate and Ammonium on Nitrogenase (C2H2 Reduction) Activity of Swards of Subterranean Clover, Trifolium subterraneum L

1986 ◽  
Vol 13 (2) ◽  
pp. 257 ◽  
Author(s):  
JH Silsbury ◽  
DW Catchpoole ◽  
W Wallace
Keyword(s):  
Nitrogen Fixation ◽  
Nitrate Reductase ◽  
Root System ◽  
N2 Fixation ◽  
Nitrogenase Activity ◽  
Alternative Hypothesis ◽  
Subterranean Clover ◽  
Mineral Nitrogen ◽  
Soluble Nitrogen ◽  
Split Root System

Small swards of subterranean clover plants were grown under controlled conditions without mineral nitrogen and allowed to establish an effective nitrogen fixation system. Nutrient solutions containing nitrate from 0 to 16 mM or of ammonium from 0 to 5 mM were then applied and changes in nitrogenase activity (NA) estimated by acetylene reduction assay (AR) and the rate of hydrogen evolution (HE) for periods of up to 35 days. In two experiments a split-root system was used to enable mineral nitrogen to be applied to only one-half of a nodulated root system whilst the NA of both halves was monitored. NA by subterranean clover was very sensitive to exogenous mineral nitrogen, concentrations as low as 0.5 mM NO3- suppressing activity significantly, and 3-5 mM stopping it almost completely within 7 days. The degree of inhibition induced by concentrations between 0.5 and 3 mM NO3- was less at a photon irradiance of 1000 compared with 300 �mol quanta s-1 m-2 . Under some conditions NA continued at a reduced but steady rate in the presence of nitrate. NH4+ also markedly depressed NA but a concentration greater than 5 mM was needed to effect the same response. After NO3- was applied to an active symbiosis, nitrate reductase activity increased as NA decreased. Our results do not support the hypothesis of a direct effect of NO3- on nitrogenase due to the accumulation of toxic NO2-. Although our results allow that assimilate might be diverted from the nodules after the application of NO3- thus reducing N2-fixation, an alternative hypothesis is proposed: that nitrogenase and nitrate reductase work in a complementary manner in supplying reduced nitrogen to whole plants, and NO3- depresses N2-fixation through a regulatory system involving the level of soluble nitrogen in the plant. We conclude that nitrogen fixation by subterranean clover in the field may be depressed below its potential due to the presence of soil mineral nitrogen.

Nitrogen Fixation by Subterranean Clover at Varying Stages of Nodule Dehydration

1990 ◽  
Vol 41 (9) ◽  
pp. 1189-1197 ◽  
Author(s):  
ALLAN G. DAVEY ◽  
RICHARD J. SIMPSON
Keyword(s):  
Nitrogen Fixation ◽  
Subterranean Clover

Nitrogen and water flows under pasture - wheat and lupin - wheat rotations in deep sands in Western Australia. 1. Nitrogen fixation in legumes, net N mineralisation,and utilisation of soil-derived nitrogen

1998 ◽  
Vol 49 (3) ◽  
pp. 329 ◽  
Author(s):  
G. C. Anderson ◽  
I. R. P. Fillery ◽  
P. J. Dolling ◽  
S. Asseng
Keyword(s):  
Nitrogen Fixation ◽  
Western Australia ◽  
N2 Fixation ◽  
Supply And Demand ◽  
Subterranean Clover ◽  
High Rate ◽  
Organic N ◽  
N Mineralisation ◽  
Soil Cores ◽  
Inorganic N

Detailed studies on the eciency with which pastures and crops use soil-derived nitrogen (N) in southern Australia are limited. Inefficiencies in the N cycle are indicated by wide spread soilacidification and low N status in wheat grain. The aims of this study were to document rates of N2 fixation by subterranean clover-based pastures and narrow-leaf lupin, plant uptake of soil-derived N, mineralisation of organic N during legume and cereal phases, and export of N from pastures, lupin,and wheat in relation to climate and soil water. These measurements were undertaken in a rotation experiment conducted on a deep sand located in the northern wheat belt of Western Australia at a site with a long-term average rainfall of 460 mm. The rotations examined over 3 years were 2 years pasture-wheat and lupin-wheat. The 15N natural abundance technique was used to differentiate soil-derived N from atmospheric Nin legumes. Biomass production, grain yields, and N contents were standard plant measurements in all treatments. Net N mineralisation between growing seasons was as certained by measuring changes in soil inorganic N to 1·5 m. Growing season net N mineralisation was determined using an in situ method in which soil cores were isolated from plant roots. Anion exchange resin was used to trap NO-3 leached below the depth of the soil cores. Nitrogen fixation by subterranean clover in a mixed pasture ranged from 29 to 162 kg N/ha whereas N2 fixation by lupins was less variable, ranging from 90 to 151 kg N/ha. Pastures were large consumers of soil-derived N (range 58-154 kg N/ha), with capeweed being the most important sink (range 38-120 kg N/ha). In comparison, wheat and lupins were inefficient users of soil N, removing 29-51 kg N/ha within a season. Another 31-67 kg N/ha of inorganic N in soil was not utilised by wheat or lupin. Annual net N mineralisation ranged from 80 to 130 kg N, confirming the high rate of decomposition of organic matter in the sandy soil. Mineralisation over summer and autumn, when crop and pastures were not grown, supplied ~25% of the inorganic N produced in soil profiles in 1995 and 20-40% in1996. The study indicated that legumes used in rotations with cereals on deep sands were able to add adequate organic N to soil to insure rates of net N mineralisation sufficient to support cereal yieldsin excess of current shire averages. However, in practice, the asynchrony in supply and demand for N resulted in the inefficient use of soil-derived N by wheat.

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