Nitrogen Fixation and N Balance in Subterranean Clover Pasture Associated with Annual and Perennial Grasses

Author(s):  
D. Chen ◽  
J. Evans ◽  
P. M. Chalk ◽  
R. E. White
2000 ◽  
Vol 51 (3) ◽  
pp. 377 ◽  
Author(s):  
G. M. Lodge

Seedlings of 3 perennial grasses, Danthonia linkii Kunthcv. Bunderra, D. richardsonii Cashmore cv. Taranna(wallaby grasses), and Phalaris aquatica L. cv. Sirosa,were each grown in replacement series mixtures with seedlings ofTrifolium repens L. (white clover),Trifolium subterraneum L. var. brachycalycinum (Katzn.et Morley) Zorahy & Heller cv. Clare (subterraneanclover), and Lolium rigidum L. (annual ryegrass). Plantswere sown 5 cm apart in boxes (45 by 29 by 20 cm) at a density of 307plants/m2. Maximum likelihood estimates were usedto derive parameters of a non-linear competition model using the dry matterweights of perennial grasses and competitors at 3 harvests, approximately 168,216, and 271 days after sowing. Intra-plant competition was examined inmonocultures of each species, grown at plant spacings of 2, 5, and 8 cm apartwith plants harvested at the above times.Competition occurred in all perennial grass–competitor mixtures, exceptin those of each perennial grass with white clover and thephalaris–subterranean clover mixture (Harvest 1) and those withD. richardsonii and phalaris grown with white clover(Harvest 2). For D. richardsonii (Harvests 1 and 2) andD. linkii (Harvest 1 only) grown with white clover andthe phalaris–subterranean clover (Harvest 1), the two species in themixture were not competing. In the phalaris–white clover mixture, eachspecies was equally competitive (Harvests 1 and 2). These differences incompetition and aggressiveness reflected differences in individual plantweights in monocultures where there was an effect (P < 0.05) of species ondry matter weight per box, but no significant effect of plant spacing.These data indicated that for successful establishment,D. richardsonii and D. linkiishould not be sown in swards with either subterranean clover or white clover,or where populations of annual ryegrass seedlings are likely to be high.Phalaris was more compatible with both white clover and subterranean clover,but aggressively competed with by annual ryegrass.


1980 ◽  
Vol 20 (102) ◽  
pp. 63 ◽  
Author(s):  
RR Gault ◽  
J Brockwell

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.


2009 ◽  
Vol 49 (8) ◽  
pp. 654 ◽  
Author(s):  
Geoffrey Saul ◽  
Gavin Kearney ◽  
Dion Borg

Two pasture systems were compared at five on-farm sites across south-western Victoria between 1990 and 1996. The ‘typical’ pasture treatment mimicked the pasture and grazing management common in the region, with volunteer annual-based pastures fertilised with around 5 kg/ha phosphorus (P) each year. The ‘upgraded’ pasture treatments were resown to phalaris, perennial ryegrass and subterranean clover, and higher rates of fertiliser (13–25 kg P/ha.year) plus other nutrients were applied. Both pastures were set stocked with the participating farmers breeding ewes. Stocking rate was an emergent variable on each plot. The stocking rate on the typical treatments was based on normal farm practise. Initially, the stocking rate of the upgraded pastures was 15% higher than for the typical pastures and increased over time depending if the ewes in the upgraded pastures were heavier than those in the typical pastures. Measurements included soil fertility, pasture production, nutritive value and composition, and animal production. Net annual pasture production of the upgraded pastures was 10 500 kg/ha compared with 8700 kg/ha for the typical pastures. This average difference (18%) between the treatments was greatly influenced by the large advantage (40%) of the upgraded pasture in the wet year of 1992. Upgraded pastures had higher pasture production than typical pastures in spring but the reverse occurred in autumn. In a separate small plot experiment, the response of each pasture to higher P fertiliser applications was tested. In autumn and winter, there was a significant interaction between pasture type and P rate, with higher responses on the upgraded pastures. In spring, both pastures responded to increased P applications but the upgraded pastures were more responsive at all P rates. The upgraded pastures contained significantly higher legume content (30–50%) than the typical pastures (10–20%). The proportion of sown perennial grasses in the upgraded pasture declined from around 30 to 10% after 6 years displaced by annual grasses and broad-leaf weeds. Herbage from upgraded pastures had significantly higher crude protein content (2–7 units) and digestibility (1–10 units) than the typical pastures with the difference between the treatments increasing over time. The set stocking policy used in this experiment is likely to have exacerbated the decline in sown perennial grasses and implementation of some form of strategic or rotational grazing may have improved persistence. The experiment also highlights the importance of selecting perennial grasses able to cope with the local environment and grazing conditions. Despite the decline in perennials, these results show significant potential to improve pasture productivity and quality in south-western Victoria.


1954 ◽  
Vol 5 (2) ◽  
pp. 247 ◽  
Author(s):  
JR Harris

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.


1972 ◽  
Vol 12 (59) ◽  
pp. 608 ◽  
Author(s):  
RC Rossiter ◽  
GB Taylor ◽  
GW Anderson

Pasture swards of the annual clovers Trifolium subterraneum (CV. Geraldton), T. hirtum (CV. Kondinin), and T. cherleri (CV. Yamina), and a mixture of all three were sown on a gravelly soil at Bakers Hill, Western Australia, in 1964. All pastures were set-stocked at 5 sheep ha-l from April 1965-April 1968, and at 8 sheep ha-1 from April 1968-March 1970. From 1966 onwards the amount of pasture dry matter on offer in July and September was two to four times as great on the subterranean clover pasture as on rose or cupped clover pastures. Moreover, the subterranean clover pasture resisted invasion by volunteer annuals more strongly. The mixed clover pasture was dominated by subterranean clover by 1966, and remained so thereafter. For the first four seasons of grazing, wool production was consistently higher (on average, 14 per cent higher) on rose clover than on subterranean clover pasture, and slightly lower still on cupped clover. In the fifth season, when grazing pressure was higher than previously, the rose and cupped clovers 'crashed', and subterranean clover produced most wool. We argue that the higher wool production on rose clover during 1965-1969 was due to some factor additional to digestible organic matter intake.


1972 ◽  
Vol 12 (56) ◽  
pp. 240 ◽  
Author(s):  
KFM Reed ◽  
RW Snaydon ◽  
A Axelsen

Young sheep were rotationally grazed, at two stocking rates, on pasture sown to combinations of two legume species (lucerne or subterranean clover) and two grass species (a mixture of annual and biennial ryegrass or phalaris) at Canberra. Liveweight gains were 45 per cent greater, and wool production was 10 per cent greater, on the lucerne dominant pasture (87 per cent lucerne) than on the grass dominant subterranean clover pasture (8 per cent subterranean clover). The differences were maximum during summer, but also occurred during spring. Mortality and supplementary feed requirement on grass dominant pasture was double that on lucerne pasture. Liveweight gains were 13 per cent greater on pasture sown to ryegrass than on pasture sown to phalaris. Sheep mortality was eight times greater on the phalaris than on the ryegrass pasture, and survival feed requirements at least double. The superior animal production from lucerne pasture was due mainly to the ability of lucerne to grow during periods of low rainfall and to maintain a high production of legume in the pasture.


1975 ◽  
Vol 15 (77) ◽  
pp. 795 ◽  
Author(s):  
JA Thompson

A range of temperate annual and perennial legumes, naturalized or commonly sown in the area, was examined at three field sites in low fertility soils derived from granite on the south western slopes of the New England Region, New South Wales. They were compared over a four year period in terms of their persistence, dry matter and nitrogen production and their compatibility with associated temperate perennial grasses, The response of sown grass to nitrogen fertilizer application was also examined in the absence of legume. Ten legumes were examined at one site and six of these at the other two sites. In general, nitrogen yields were ranked similarly to total dry matter yields of all treatments, including grasses in the absence of legume. However, the legumes were ranked differently in terms of productivity of the legume component and productivity of associated grass. At all sites lucerne gave the highest yields of total dry matter and of legume and the lowest yield and persistence of associated grass-comparable to grass growing in the absence of legume or applied nitrogen. Subterranean clover was ranked second or third in total dry matter yield, depending on site, but provided the highest yield of associated grasscomparable to grass receiving high levels of applied nitrogen. Under this legume soil nitrogen levels tended to be highest. Rose clover, sown at one site only, yielded more legume dry matter than subterranean clover but grass yield was comparable to that with lucerne. The results suggest that subterranean clover is the superior legume for successful mixed sowings although inclusion of white clover could be justified. Lucerne appears to be best sown as a pure sward.


1963 ◽  
Vol 3 (8) ◽  
pp. 35 ◽  
Author(s):  
VR Squires

Three herbicides, 2,2- DPA (2,2-dichloropropzonzc acid), diquat dibromide (9, l0-dihydro-8a, 10a-dizonia phenanthrene dibromide) and paraqmt di (methyl sulphate) (1,l-dimethl-4,4,-bipryridylium di (methyl sulphate) ) were tested with a view to controlling barley grass (Hordeum leporinum Link) in clover pastures. The tolerance of white clover (Trifolium repens L.) and subterranean clover (T. subterraneum L.) to sodium 2,2-DPA was determined. 2,2-DPA caused severe damage to subterranean clover (resulting in the loss of one season's production) and slight damage to white clover at a rate which controlled the grass-2 lb an acre acid equivalents. Diquat dibromide applied at 2 lb an acre (active cation) in mid winter gave complete control of barley grass in a subterranean clover pasture. Springfields of clover on treated plots were double those of the unseated control. Paraquat di (methyl sulphate) gave satisfactory control of barley, grass at 0.5 lb an acre, as an early post emergence spray, with no increase in subterranean clover yields, At the 1 lb an acre rate barley grass control was complete.


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