Field studies of the effects of pre-sowing weed control and time of sowing on tropical perennial grass establishment, North-West Slopes, New South Wales

2010 ◽  
Vol 61 (2) ◽  
pp. 182 ◽  
Author(s):  
G. M. Lodge ◽  
M. A. Brennan ◽  
S. Harden

Two separate experiments on the North-West Slopes of New South Wales investigated: (1) the effects of differing lengths of pre-sowing weed control (2 years, 1 year, and 3–4 months in the spring immediately before sowing) on the soil seed density of liverseed grass (Urochloa panicoides) from November 2005 to November 2007 and its seedling density at establishment (December 2007), as well as on subsequent herbage mass and plant frequency of this species and Panicum coloratum var. makarikariense cv. Bambatsi (Expt 1); and (2) the effects of cultivar, time of sowing (November 2006, January 2007, and March 2007), and defoliation in the autumn after sowing, on the over-wintering ability of 5 tropical perennial grasses (Expt 2). The cultivars sown in Expt 2 were Bambatsi, Dichanthium aristatum cv. Floren, Chloris gayana cv. Katambora, Digitaria eriantha var. eriantha cv. Premier, and Bothriochloa bladhii var. glabra cv. Swann. At sowing (November 2007), liverseed grass seed and seedling densities in Expt 1 were lowest (P < 0.05) in the 2-year pre-sowing weed control treatment (15 and 13/m2, respectively), and the subsequent herbage mass of Bambatsi (January and October 2008) was highest (P < 0.05) in this treatment. In Expt 2, 59 frosts occurred in 2007, and Floren, Bambatsi, and Swann sown in March of that year over-wintered poorly and had lower (P < 0.05) herbage mass and plant frequency in the following spring compared with the other sowing times. These differences were also evident in autumn and spring 2008, up to 23 months after sowing.

1981 ◽  
Vol 29 (2) ◽  
pp. 121 ◽  
Author(s):  
GM Lodge

Emergence and survival of the seedlings of warm-season native perennial grasses Aristida ramosa R.Br., Bothriochloa macra (Steud.) S . T. Blake, Dichanthium sericeum (R.Br.) Camus, Sporobolus elongatus R.Br., Eragvostis leptostachya Steud. and Chloris truncata R.Br. and the cool-season species Stipa variabilis Hughes and Danthonia linkii Kunth were studied in both native pastures and sown monospecific plots on the north- west slopes of New South Wales. The most favourable period for the successful emergence and establishment of warm-season grasses was from mid summer to early autumn. Cool-season native perennial grasses established best from seedlings that appeared from mid autumn to late winter. Few seedlings were observed to germinate in spring, probably as a result of large variations in temperature, low minimum temperatures or intra and interspecific competition. Seedlings growing in native pasture spent long periods in the vegetative phase compared to the early flowering of seedlings in the sown plots. In the pasture studied only two seedlings flowered over 700 days after emergence, and many others after persisting for up to 2 years died without producing seed. These findings indicate that the seedlings in these native pastures were under considerable stress and that the adult populations of the species examined were relatively stable and little recruitment occurred.


2001 ◽  
Vol 23 (2) ◽  
pp. 159 ◽  
Author(s):  
D. T. Vere ◽  
R. E. Jones ◽  
M. H. Campbell

Pastures are the basis of most forms of agricultural production on the New South Wales central and southern tablelands. Pastures occupy the bulk of the region's landmass and pasture-based livestock production annually contributes more than three-quarters of the regional gross value of rural production. Throughout the region, there is substantial variation in pasture composition, ranging from high quality introduced perennial grasses and legumes to pastures comprising mainly low quality native species. This paper examines the economics of the main categories of temperate pastures over a range of soil fertility-rainfall environments on the south-eastern tablelands areas of New South Wales. Using a linear programming model and discounted development budgets, the results demonstrate the strong influence of the environment on the economics of the individual pasture systems. The highest economic returns in both the short and longer-terms were to the introduced perennial grass pastures in most of the environments. Pastures based on introduced legumes and the high quality native species also generated sound economic returns, although there are recognised problems with the persistence of the legume pastures. Over time, the returns to the better quality native pastures compare favourably with the introduced legumes and are better suited to acidic soils than the perennial grasses. Low quality native species produced relatively poor economic returns in all environments and unfortunately, are the main pasture type in the region's less favourable environments.


2003 ◽  
Vol 43 (4) ◽  
pp. 357 ◽  
Author(s):  
W. S. Semple ◽  
I. A. Cole ◽  
T. B. Koen

Thirty perennial grass accessions were evaluated for emergence, growth and persistence at 6 severely salinised seepage scalds on the western slopes of New South Wales. Warm-season accessions were sown or planted in spring 1996 and 1997, and cool-season types in autumn 1996 and 1997. Control species, tall wheat grass (Thinopyrum ponticum) and puccinellia (Puccinellia ciliata) were sown in spring and autumn. Plants were monitored over 2 growing seasons. None of the accessions, including the controls, performed well at all sites. Of the accessions established from seed, tall wheat grass was the most reliable in terms of the number of successful establishments but its growth potential was only achieved at a few sites. Some warm-season species (Panicum coloratum, Chloris gayana and Cynodon dactylon) approached their growth potential at some sites but overall rates of establishment were very low. The performance of puccinellia appeared to be adversely affected by low pH. It was concluded that on severely scalded sites, vegetative propagation of stoloniferous–rhizomatous plants, e.g. Pennisetum clandestinum, Paspalum vaginatum and C. gayana, may be the best option.


2000 ◽  
Vol 40 (6) ◽  
pp. 831 ◽  
Author(s):  
G. A. Wicks ◽  
W. L. Felton ◽  
R. D. Murison ◽  
R. J. Martin

Four experiments in northern New South Wales comparing fallow management treatments of no-tillage, cultivated with the stubble retained, and cultivated with the stubble burned, from 1981 to 1990, were sampled for weeds between wheat harvest and seeding on a number of occasions during this period. Eighty weed species were identified, 23 of which were found at all 4 sites but only 13 were recorded in the samples taken. These were dwarf amaranth, wild turnip, spear thistle, Australian bindweed, fleabane, bladder ketmia, prickly lettuce, turnip weed, variegated thistle, common sowthistle, dandelion, wild oats and native millet. The density of weeds during the fallow period decreased by 97% from 1981 to 1990 with some species eliminated, probably because of the herbicides used, particularly glyphosate and chlorsulfuron. These included Boggabri and redroot amaranth, button grass, caustic weed, dense crassula, fat hen, legumes, common peppercress, hedge mustard, London rocket, shepherd’s purse, wild mustard, sorghum-almum, paradoxa grass, wild zinnia, and wireweed. Twenty-four weed species were classified as a problem or a potential problem in the future at 1 or more sites. Seventeen weed species, including perennial grasses, often were tolerant to glyphosate at the rates used. The densities of common sowthistle and wild oat were reduced after 10 years, but still remained at all 4 sites. Plant density of species with wind-blown seeds was greater in no-tillage plots than stubble-retained or stubble-burned plots. Weeds whose seeds are dispersed by wind and weeds tolerant to glyphosate were the most troublesome. The perennial grass native millet increased at all 4 sites.


2001 ◽  
Vol 23 (2) ◽  
pp. 204 ◽  
Author(s):  
G. M. Lodge

Total and germinable soil seedbanks (litter and soil) were studied for a native pasture and three sown pastures (dominated by Phalaris aquatica L. cv. Sirosa) in northern New South Wales from 1993 to 1996. Soil core samples were taken from continuously grazed plots for both pasture types and two oversown treatments in the native pasture and from a spring-autumn rest treatment at the sown pasture sites. At each site above ground herbage mass was also estimated regularly as part of the Temperate Pasture Sustainability Key Program. For all sites and treatments, the proportion of germinable seeds as a percentage of the total (dormant and germinable) seedbank ranged from 1–26% for the native pasture and 1–39% for the sown pastures. Germinable seed numbers ranged from 280 to 26,110 seeds per m2, while total seedbank numbers were from 6700 to 178,360 seeds per m2. Native pasture herbage mass was dominated by native perennial grasses, but seeds of these species were less than 20% of the total seed bank in all treatments in 1994 and 1995. At the sown pasture sites, most of the germinable (51–92%) and total (65–97%) seedbanks were either barnyard grass (Echinochloa crus-galli (L.) Beauv, annual ryegrass (Lolium rigidum Gaudin), subterranean clover (Trifolium subterraneum L.) or wireweed (Polygonum aviculare L.). Since seeds of annuals and other forbs generally dominated both the total and germinable seedbanks of these perennial grass-based pastures, these species were likely to increase over time. Seeds of the sown perennial grass Phalaris aquatica L, cv. Sirosa were less than 1% of the total seedbanks in pastures sown in 1990 and less than 3% of those sown in 1979. With above average summer rainfall at the native pasture site in 1996 and prolific growth of redgrass, seeds of this species were 38–63% of the total and 11–29% of the germinable seedbank in May 1996. Except at this site and time, the species composition of the total and germinable seedbanks did not generally reflect the dominance of the above ground herbage mass of these pastures by perennial grasses.


2003 ◽  
Vol 25 (1) ◽  
pp. 56 ◽  
Author(s):  
D. Vere ◽  
P. Dowling

The latter part of the 20th century has seen a persistent decline in the productivity of some types of sown pastures on the central and southern tablelands of New South Wales. Currently, much research effort is directed to stabilising the perennial grass component of these pastures. This paper evaluates the economic justification of that emphasis. It is argued that trends in livestock production can usefully represent increases or decreases in the stocks of three broad categories of sown pastures that are defined as being those pastures sown to introduced perennial grasses and legumes (perennial grasses), introduced legumes only (legumes), and the total of both these categories. Regression methods were used to determine the changes that have occurred in the livestock production from these pastures that could be explained by changes in a range of economic and other variables. The estimated models were then used to forecast wool, beef and lamb production from each pasture type. The results indicate that changes in prices and costs have influenced the trends in animal production from these pastures and that the structures of these influences have changed over time. Production from perennial grass-legume pastures has remained high relative to production from legume pastures despite adverse cost-price trends. The forecasts indicated a continuation of present levels of perennial grass-legume pasture areas but a decline in production from the legume pastures. The results support the concerns about the continued deterioration in the legume only pastures and the thrust of R&D programs that promote the benefits of perennial grass-legume pastures. The use and analysis of public data to improve understanding of the economic factors that influence the long-term stability of intensively grazed rangelands is highlighted.


1996 ◽  
Vol 18 (1) ◽  
pp. 80 ◽  
Author(s):  
CA Booth ◽  
F Sanchez-Bayo ◽  
GW King

Growth and survival of hopbush (Dodonaea attenuata), turpentine (Eremophila sturtii) and punty bushes (Cassia eremophila and C. artemisioides) were studied in relation to the effects of grazing and shrub density, at four sites in the Bourke-Wanaaring region of western New South Wales during 1979 to 1982. Hopbush shrubs grew faster than turpentine and punty bushes. Small hopbush grew better on open areas, while mature shrubs grew better in dense stands. Turpentine showed better performance in open areas, and punty bush growth was unaffected by shrub population density. All these species showed a high survival rate, particularly in height classes greater than 25 cm, and they kept growing even during drought periods. The effects of grazing on survival were inconclusive. Hopbush and turpentine root development was rapid, attaining depths of over 1.1 m in wet soils, 14 weeks after germination. Mature plants in the field, both hopbush and turpentine, were observed to have extensive lateral root networks at either 22 cm or 30-70 cm soil depth respectively, as well as a tap root system. The characteristics of both species help explain the competitive advantage of these shrubs over herbaceous species, and their survival capability in times of drought. Competition of hopbush with the perennial grass woollybutt (Eragrostis eriopoda) and annual herbage was also examined. In spring, survival of hopbush seedlings was favoured within woollybutt tussocks, this situation being reversed in autumn. Woollybutt biomass was negatively affected by the proximity of hopbush shrubs. Annual herbage seemed not to have any effect on hopbush survival, although shrub seedlings grew better under conditions of moderate herbage cover. Microtopography affected the establishment of both grasses and shrubs, with depressions favouring the growth of grasses at the expense of shrubs during periods of adequate moisture, and the growth of shrubs during drier times. The findings suggest that the woody weed problem is unlikely to wax and wane and that turpentine may be particularly difficult to control. Maintenance of high levels of pasture cover from perennial grasses and annuals may slow down recruitment and growth in open areas with scattered parent shrubs, where control will be less costly, and may contain future spread.


1996 ◽  
Vol 18 (2) ◽  
pp. 309 ◽  
Author(s):  
PM Dowling ◽  
DR Kemp ◽  
DL Michalk ◽  
TA Klein ◽  
GD Millar

The influence of grazing management, herbicide and fertiliser on botanical change in two perennial grass based pastures was assessed over six years at two sites in central New South Wales. Ten treatments at both sites compared continuous grazing, three seasonal rests from grazing (autumn, winter, summer), and herbicide application for seedling grass control, each at two levels of fertiliser addition (nil, recommended). These treatments were designed to screen options for management rather than devise complete systems. In a degraded perennial pasture dominated by annual grasses, the proportion of perennial grasses and forbs increased with summer rests, especially at the recommended fertiliser level. Legumes increased with herbicide application, and annual grasses remained high in the continuously grazed control and other treatments. There were no significant effects on composition from autumn or winter rests. On the summer rest treatment at the recommended fertiliser level, perennial grasses (mostly cocksfoot) increased from 11% to 30% compared with the control where perennial grass declined below 5%. The increase was due to both recruitment and increase in size of existing plants, as a consequence of resting the perennial grasses when actively growing, flowering and setting seed, in favourable seasons. In contrast, on the better quality perennial pasture dominated by phalaris, there were limited management effects and perennial grasses increased on all treatments over time. The absence of a response at this site was attributed to a lenient stocking rate, dominant perennial grasses and limited rainfall during periods when active growth might be expected. Summer rests in this case also led to a small increase in forbs. The data suggest that perennial grasses can be encouraged with a conservative stocking policy that maintains the available feed-on-offer above 1 t DM/ha through seasons of active growth.


1978 ◽  
Vol 18 (92) ◽  
pp. 361 ◽  
Author(s):  
GE Robards ◽  
DL Michalk ◽  
RJ Pither

A four year experiment is reported during which breeding Merino ewes grazed two natural pasture types at three stocking rates at Trangie in central-western New South Wales. Initially, the pasture on a red brown soil was dominated by cool season annual species, particularly Hordeum leporinum, Erodium species and Medicago species. The pasture on a heavier grey soil was dominated by the perennial grasses Chloris acicularis, C. truncata and Stipa variabilis. Clean wool production of ewes grazing the annual-dominated pasture was significantly (P< 0.05) higher than that of ewes grazing the perennial grass-dominated pasture even though the wool of the ewes grazing perennial pasture had a higher percentage clean yield (P < 0.05). The ewes on the annual-dominated pasture were significantly heavier in autumn and winter, and had a faster rate of wool growth in each season except spring, than ewes grazing perennial pasture. Number of lambs born per ewe, lamb birth weight and lamb growth rate were not affected by pasture type or stocking rate. Stocking rate had a small but statistically significant effect on clean wool production and only small effects on ewe liveweight, regardless of pasture type. When hand feeding of the pregnant ewes became necessary in the poor winters of 1971 and 1972 all stocking rates had to be commenced simultaneously. The significance of perennial grasses in these natural pastures is discussed in relationship to animal production, stocking rate, pasture and soil stability, and regeneration of grasses following favourable seasons.


1997 ◽  
Vol 37 (1) ◽  
pp. 19 ◽  
Author(s):  
M. Freer ◽  
J. R. Donnelly ◽  
A. Axelsen ◽  
L. F. Myers ◽  
J. L Davidson ◽  
...  

Summary. In 2 field experiments on the southern highlands of New South Wales, the short-lived perennial grass secale (Secale montanum Guss. cv. Black Mountain) was grazed by Merino wether weaners at stocking rates of 10–17 animals/ha to test the suggestion that persistence might be enhanced by occasional deferment of grazing to encourage seedling germination. In the first of these experiments (experiment 1), designed to compare secale and phalaris, when accompanied by white and subterranean clovers, growth and survival of both grasses was poor, despite the application of >600 kg/ha superphosphate and the experiment was abandoned after 2 years. A subsequent pot trial (experiment 2) with secale grown in soil from the experimental site, where the fertiliser had been applied, showed a large growth response to additional phosphorus. Because inadequate soil fertility may have been the cause of poor grass persistence in experiment 1, a second field experiment (experiment 3) was established on the same site to compare secale, perennial ryegrass and cocksfoot, each accompanied by white and subterranean clovers and with the application of a further 850 kg/ha superphosphate over 3 years. Initial growth of all the grasses was good and animal production on the secale and ryegrass plots was high (up to 100 kg/ha greasy wool and 300 kg/ha liveweight gain). Secale failed to survive more than 3 years, despite deferment of grazing and it may be that persistence depends more on the reliability of autumn rainfall. However, mean weight gain from the clovers and volunteer grasses on the secale plots in the fourth year was as high as from the ryegrass plots and double that from the cocksfoot plots, which became increasingly cocksfoot-dominant. While the results indicate a need for more work on the fertiliser requirements of perennial grasses on these soils, they also raise questions about whether these grasses benefit animal production sufficiently to justify the cost of establishing them.


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