Manipulation of buried seed reserves by timing of soil tillage in Mediterranean-type pastures

1986 ◽  
Vol 26 (1) ◽  
pp. 71 ◽  
Author(s):  
F Forcella ◽  
AM Gill

Environmental requirements for seed germination and seedling growth vary appreciably among pasture species. Therefore, it is possible that the botanical composition of pastures may be manipulated by timely seasonal exposure of the soil-seed reserve to conditions that promote germination differentially. This possibility was examined in two Mediterranean type pastures in which plots were tilled once per year, each in a different month, for 2 years. For several pasture species, effects were estimated with respect to numbers of soil seeds, numbers of emergent seedlings and canopy coverage. Individual species showed specific behaviour patterns. Seeds of sorrel (Rumex acetosella) and wireweed (Polygonum aviculare) maintained abundant seed in the soil, those of annual ryegrass (Lolium rigidum) and subterranean clover (Trifolium subterraneum) were less persistent, and seeds of red brome (Bromus rubens) and silvergrass ( Vulpia spp.) occurred only seasonally in the soil-seed pools. Mature plants of red brome, silvergrass and subterranean clover attained dominance only in summer and early autumn-tilled plots. Annual ryegrass was more abundant when soil was cultivated in late autumn and early winter, whereas sorrel and wireweed were significant only in plots ploughed in winter. Thus botanical composition may be altered radically by time of tillage, and this has several practical implications for pasture management and weed control.

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.


2019 ◽  
Vol 70 (9) ◽  
pp. 800
Author(s):  
John W. Piltz ◽  
Simon J. Flinn ◽  
Leslie A. Weston

Barley grass (Hordeum spp.) is a relatively short lived annual that provides high quality grazing early in the season, but its seed heads cause contamination of wool and carcasses, and may irritate the mouth, eyes and nose of sheep. Treatments were imposed on established subterranean clover (Trifolium subterraneum L.) annual pasture in the same plots for three consecutive years (2015 to 2017) to evaluate changes in barley grass content. Treatments included: grazing alone (G), herbicide followed by grazing (HG), or a forage conservation harvest in early October, late October or early November consistent with an early silage harvest (ES), late silage harvest (LS) or hay cut (H). Grazing plus herbicide markedly reduced (P &lt; 0.05) barley grass numbers compared with all other treatments, but increased (P &lt; 0.05) the growth of annual ryegrass (Lolium rigidum L.). ES reduced (P &lt; 0.05) barley grass and increased (P &lt; 0.05) subterranean clover compared with H, but broadleaf weed content benefitted by LS in contrast to either ES or H. Although herbicide application was the most effective method for barley grass control, forage harvest timing could be used to beneficially manipulate pasture composition.


1983 ◽  
Vol 34 (4) ◽  
pp. 403 ◽  
Author(s):  
AC McKay ◽  
JM Fisher ◽  
AJ Dube

To control the nematode Anguina funesta (considered by some to be A. agrostis), the vector in annual ryegrass toxicity, pasture management treatments were applied before and after gall initiation. Before gall initiation, the herbicides paraquat and diclofop methyl were used to remove ryegrass. These treatments gave good control of the nematode, but reduced pasture production in winter when feed is generally scarce. Diclofop methyl had no detrimental effect on legume growth, and was more effective on actively growing ryegrass than was paraquat, which severely retarded subterranean clover. Desiccating the ryegrass heads, with mechanical topping or the desiccant herbicide paraquat, after gall initiation, but before hatching of the second-stage juveniles ( J2s ) , gave good control of the nematode population. The main limitations with mechanical topping are that the ryegrass heads must be tall enough to cut before the J2s hatch and not all paddocks are suitable for topping. With paraquat, the main limitations are that treated material was susceptible to weathering and there was less regrowth to set seed. Oxamyl, a systemic nematicide applied after gall initiation, had no effect on the nematode, nor had spraying pasture with the nematode parasitic fungus Verticillium sp.


1973 ◽  
Vol 13 (64) ◽  
pp. 556
Author(s):  
DW Barrett ◽  
GW Arnold ◽  
NA Campbell

Pastures containing subterranean clover (Trifolium subterraneum) and either Vulpia spp. or Bromus rigidus as the other major species were sprayed at 0, 0.07, 0.14 and 0.21 kg a.i. ha-1 of paraquat ion between June and early October in Western Australia. Spraying removed the grasses and produced pastures containing up to 95 per cent clover. Mid-winter applications were more effective in increasing clover content than those made in spring. These changes in botanical composition were evident in the year following spraying, but were less marked. Yields of dry matter were reduced by paraquat, especially 'in the period immediately following spraying. These losses tended to decline as the growing season progressed, but at the close they were still evident on the Bromus rigidus pasture sprayed in July. Yields at the end of the subsequent season were similar on all treatments. Paraquat applied in mid-August at 0.14 kg a.i. ha-1 to both pastures produced the greatest change in botanical composition with the minimum loss of yield. The concentrations of nitrogen, phosphorus, calcium and magnesium were higher in mature herbage on paraquat treatments. Total yields of nutrients were similar between treatments because of reduced dry matter yield.


2003 ◽  
Vol 43 (1) ◽  
pp. 61 ◽  
Author(s):  
G. D. Li ◽  
K. R. Helyar ◽  
C. M. Evans ◽  
M. C. Wilson ◽  
L. J. C. Castleman ◽  
...  

Two permanent pastures (annual pasture v. perennial pasture) were established in 1992 as part of the long-term field experiment, MASTER — Managing Acid Soils Through Efficient Rotations. The primary objective of the experiment was to develop an agricultural system that is economically viable and environmentally sustainable on the highly acidic soils in south-eastern Australia. This paper reports on the effects of lime on the botanical composition changes of annual and perennial pastures over 9 years. In general, lime increased the proportion of the desirable species, such as phalaris (Phalaris aquatica) in perennial pasture and subterranean clover (Trifolium subterraneum) in annual pastures, and decreased the proportion of the undesirable species, such as Vulpia spp., in both annual and perennial pastures, ultimately improving the quality of feed-on-offer to animals. As a result, the limed pastures carried 24% more sheep than the unlimed pastures, while maintaining individual animal performance similar for both limed and unlimed pastures. The phalaris-based perennial pasture was more stable in terms of maintaining the sown species than the annual pasture. Lime improved the persistence of phalaris and the longevity of the phalaris-based pasture should be at least 10 years. Lime changed the direction of plant succession of annual pastures. Without lime, Vulpia spp. gradually became more dominant while ryegrass and subterranean clover became less dominant in annual pastures. With lime, barley grass (Hordeum leporinum) gradually invaded the sward at the expense of ryegrass, thus reducing the benefits of lime, but this effect was less for the perennial pastures than for annual pastures. Liming perennial pastures should be more beneficial than liming annual pastures because of the beneficial effects on pasture composition. In addition, previously published work reported that liming perennial pastures improved sustainability through better use of water and nitrogen.


2011 ◽  
Vol 62 (3) ◽  
pp. 236 ◽  
Author(s):  
S. A. Conning ◽  
M. Renton ◽  
M. H. Ryan ◽  
P. G. H. Nichols

Biserrula (Biserrula pelecinus L.) is a recently domesticated annual pasture legume developed for ley farming systems that have traditionally relied upon subterranean clover (Trifolium subterraneum L.). This study examined competitive interactions between biserrula and subterranean clover and the common broad-leaf weed capeweed (Arctotheca calendula L.) during seedling establishment and vegetative growth, in order to develop guidelines for successful legume pasture management. Two glasshouse experiments were conducted to investigate the allocation of biomass to roots and shoots in biserrula, capeweed, and subterranean clover and its relationship with competitive ability in the first 100 days after sowing. In Experiment 1, capeweed had a higher relative growth rate of shoots and roots than the two legumes and developed a more extensive root system. Experiment 2 consisted of growing binary mixtures of the three species at different densities. The effect of competition on the biomass of biserrula, capeweed, and subterranean clover was best modelled by a power–exponential model. Increasing capeweed densities suppressed the biomass production of both biserrula and subterranean clover, whereas capeweed biomass increased with increasing densities of subterranean clover. This study suggests that the competitive advantage of capeweed is mainly conferred during the seedling stage. It also suggests that biserrula and subterranean clover germinating at the same time can co-exist as a mixed sward, at least up until flowering, if biserrula density is high relative to subterranean clover.


2001 ◽  
Vol 41 (8) ◽  
pp. 1109 ◽  
Author(s):  
R. A. Waller ◽  
P. W. G. Sale ◽  
G. R. Saul ◽  
G. A. Kearney

A 4-year field experiment was carried out in south-western Victoria to determine whether tactical stocking might improve perennial ryegrass (Lolium perenne L.) persistence and prime lamb production, compared with the more common practice of continuous stocking. Tactical stocking consisted of variable-length summer, autumn and winter rotations and continuous stocking in spring. The 2 grazing strategies were compared on 2 contrasting pastures: an upgraded pasture, sown with newer cultivars of perennial ryegrass and subterranean clover (Trifolium subterraneum L.) with 26 kg phosphorus/ha.year, and a more typical naturalised perennial ryegrass pasture receiving 6 kg phosphorus/ha.year. Paddocks were grazed by Border Leicester x Merino ewes, which were mated to a terminal sire to lamb in September. The effects of the grazing systems and pasture treatments on ryegrass persistence and pasture botanical composition are presented in this paper. The perennial ryegrass component of the sward decreased from an average mass of 1000 kg dry matter/ha on the upgraded pasture and 400 kg dry matter/ha on the typical pasture in spring 1996 to 100 kg dry matter/ha and <50 kg/ha for the 2 pasture types, respectively, in spring 1998. This occurred irrespective of the grazing system imposed. The decline of ryegrass was attributed to several factors including the very dry 3-year period, summer rainfall events that caused ryegrass buds to break dormancy then die when dry conditions resumed, the gravelly soil type where the experiment was located, and the high grazing pressure used. A number of species became more prevalent in the pastures as the ryegrass disappeared. Silver grass (Vulpia spp.) increased 4–5-fold on all treatments. By the fourth year, barley grass (Hordeum leporinum) and Bromus spp. had increased significantly with tactical stocking compared with continuous stocking. Capeweed (Arctotheca calendula L.) and Erodium spp. increased on both the continuously stocked and upgraded pastures. The subterranean clover component was maintained across all treatments over the 4 years, indicating that tactical stocking did not adversely affect clover persistence. Since ryegrass declined irrespective of treatment, the tactical stocking system used in this study cannot be recommended for improving ryegrass persistence.


1961 ◽  
Vol 1 (2) ◽  
pp. 81
Author(s):  
KD McLachlan

Superphosphate was applied in summer (December) or in autumn (March) to an existing mixed pasture of subterranean clover (Trifolium subterraneum L.) and phalaris (Phalaris tuberosa L.), growing on apodsolic soil of p H 5.8. Time of application effects were recorded at the lowest level of applied phosphate. The main effect was on the botanical composition of the pasture. The summer application favoured clover, the autumn one grass. This effect is explained as a change in the relative ability of the species to compete for superphosphate. These results suggest how time and rate of application of superphosphate may be used to manage pasture composition. In the first year, when clover growth was encouraged, the earlier application also increased the total yield of pasture. In the second and third years, changes in the yield of grass were offset by changes ill the yield of clover and the effect of time of application on total pasture yield was not significant.


1968 ◽  
Vol 8 (35) ◽  
pp. 706 ◽  
Author(s):  
DF Smith

The effects of three grazing treatments and three mowing treatments on the dominance of barley grass (Hordeum leporinum) in an annual pasture were examined. Different spring grazing patterns did not markedly alter the amount of seed. Mowing favoured the legume component; topping less so than cutting lower as for hay or silage. However, none of these practices totally prevented barley grass from setting seed, and their effects were partly offset by late irrigation. Oversowing with subterranean clover (Trifolium subterraneum) did reduce barley grass seed setting but alone u-as not effective in changing botanical composition. Compared with Wimmera ryegrass (Lolium rigidum), barley grass showed greater persistence.


1973 ◽  
Vol 13 (65) ◽  
pp. 669 ◽  
Author(s):  
JG McIvor ◽  
DF Smith

The effects of deferred autumn grazing on a pasture comprising nearly equal proportions of subterranean clover (Trifolium subterraneum), capeweed (Arctotheca calendula) and annual grasses were measured over two growing seasons. Autumn deferment increased the survival of capeweed seedlings in both years and of clover in one year but had little effect on the annual grasses. Although there was more herbage present on the deferred plots in early winter, under later set stocking at normal levels by spring the amount of herbage present, plant density, botanical composition and seed numbers were similar on all plots. The accumulation of herbage under deferred grazing caused an elevation of shoot apex height in capeweed, but not in clover. When combined with subsequent intensive grazing, the number of capeweed plants surviving to flowering was sharply reduced. However, this management also resulted in a reduction in herbage production in spring.


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