Trade-offs between productivity and ground cover in mixed farming systems in the Murrumbidgee catchment of New South Wales

2009 ◽  
Vol 49 (10) ◽  
pp. 837 ◽  
Author(s):  
J. M. Lilley ◽  
A. D. Moore
Keyword(s):  
Management Practices ◽  
New South ◽  
Ground Cover ◽  
Stocking Rate ◽  
Farm Productivity ◽  
South Wales ◽  
Wheat Stubble ◽  
The Mean ◽  
The Impact

Inadequate ground cover because of over-grazing of pastures, fallowing and stubble burning or excessive cultivation exposes land to degradation, yet maintaining cover can constrain productivity. We used long-term simulation analysis to investigate the impact of modifying stock and crop management practices on the trade-off between farm productivity (grain, meat and wool) and ground cover levels. Management of mixed farms at five locations (426–657 mm mean annual rainfall) in the Murrumbidgee catchment of New South Wales was represented for simulated farms that included permanent pastures, crop–pasture rotations, and a meat/wool sheep enterprise. Locations varied in their stocking rate, soil characteristics and proportion of land area allocated to various crops and pastures. At each location we investigated the impact on ground cover and farm productivity of (1) retention of wheat stubble, (2) altering stocking rate (up to ±25%) and (3) moving stock elsewhere on the farm when the mean value of ground cover fell below a given threshold (50, 60, 70, 80 or 90%) for either, all pasture on the farm or an individual paddock. The analysis showed that seasonal conditions were the dominant effect on the mean farm cover (mean range 64–98%); cover fell as low as 43–57% in severe droughts, depending on location. Retention of wheat stubble increased long-term mean cover by 1–4%, with little impact on grain yield. Altering stocking rate had the largest impact on cover at all locations (up to 4%), although there was a trade-off with productivity. Maintaining a constant stocking rate, although moving stock within the farm, had a small, positive effect on the whole-farm cover, although it reduced gross margin because of the cost of supplementary feeding. Confining stock to a 3 ha feeding lot was the most effective strategy for maintaining ground cover and minimising financial loss. Our analysis did not account for the benefits of maintaining high levels of ground cover on the long-term productive capacity of the farm through on-farm or off-farm environmental benefits. We conclude that ground cover is dominated by climatic effects, and that within the range of stock management practices examined in the present study, practices that increase minimum cover levels also reduce farm productivity. Reducing total stocking rate, or removing stock from the farm during periods of low cover, will have the greatest impact on maintaining cover, although it will reduce whole-farm profit.

Surface soil water dynamics in pastures in northern New South Wales. 2. Surface runoff

2004 ◽  
Vol 44 (3) ◽  
pp. 283 ◽  
Author(s):  
S. R. Murphy ◽  
G. M. Lodge ◽  
S. Harden
Keyword(s):  
Soil Water ◽  
Surface Runoff ◽  
New South ◽  
Ground Cover ◽  
Simulation Modelling ◽  
Runoff Generation ◽  
Grazed Pastures ◽  
South Wales ◽  
Runoff Events

Surface runoff can represent a significant part of the hydrological balance of grazed pastures on the north-west slopes of New South Wales, and is influenced by a range of rainfall characteristic, soil property, and pasture conditions. Runoff plots were established on grazed pastures at 3 sites as part of the Sustainable Grazing Systems National Experiment (SGS NE). Pastures were either native (redgrass, wallaby grass and wire grass) or sown species (phalaris, subterranean clover and lucerne) and a range of grazing management treatments were imposed to manipulate pasture herbage mass, litter mass and ground cover. Rainfall and runoff events were recorded using automatic data loggers between January 1998 and September 2001. Stored soil water in the surface layer (0–22.5 cm) was monitored continuously using electrical resistance sensors and automatic loggers. Pasture herbage mass, litter mass and ground cover were estimated regularly to provide information useful in interpreting runoff generation processes.Total runoff ranged from 6.6 mm at Manilla (0.3% of rainfall) to 185 mm at Nundle (5.7% of rainfall) for different grazing treatments, with the largest runoff event being recorded at Nundle (46.7 mm). Combined site linear regression analyses showed that soil depth, rainfall depth and rainfall duration explained up to 30.3% of the variation in runoff depth. For individual sites, these same variables were also important, accounting for 13.3–33.6% of the variation in runoff depth. Continuous monitoring of stored soil water in relation to these runoff events indicated that the majority of these events were generated by saturation excess, with major events in winter contributing substantially to regional flooding. Long-term simulation modelling (1957–2001) using the SGS Pasture Model indicated that most runoff events were generated in summer, which concurred with the number of flood events recorded at Gunnedah, NSW, downstream of the SGS sites. However, floods also occurred frequently in winter, but the simulations generated few runoff events at that time of the year. These results have important implications for sustainability of grazed pastures and long-term simulation modelling of the hydrological balance of such systems, since runoff generation processes are likely to vary both spatially and temporally for different rainfall events.

The impact of livestock grazing on the persistence of a perennial forb in a temperate Australian grassland

2003 ◽  
Vol 9 (4) ◽  
pp. 302 ◽  
Author(s):  
Josh Dorrough ◽  
Julian Ash
Keyword(s):  
Plant Species ◽  
Management Practices ◽  
Livestock Grazing ◽  
Grazing Management ◽  
Population Growth Rates ◽  
Perennial Plant ◽  
South Wales ◽  
Recent Occurrence ◽  
The Impact

The presence of perennial plant species in grazed habitats may be an imperfect predictor of their long-term ability to persist under grazing by livestock. This is particularly the case in landscapes where grazing by livestock is a relatively recent occurrence or where management practices are leading to intensification of grazing. This paper investigates the impacts of grazing on the native perennial inter-tussock forb Leptorhynchos elongatus (Asteraceae) in grasslands on the Monaro Tablelands of New South Wales. Although the species persists in grazed habitats, exclosures indicate that current grazing management can lead to severe depletion of seed, largely due to selective removal of flowers and seed heads by livestock. A population model suggests that under current grazing management, population growth rates may be negative. Removal of livestock during flowering and seed set may assist long-term persistence of this species in grazed habitats. Despite almost 200 years of livestock grazing on the Monaro Tablelands, recent intensification of grazing management could result in the future loss of some plant species in grazed habitats.

Spatial Distribution of Sheep, Feral Goats and Kangaroos in Woody Rangeland Paddocks.

1996 ◽  
Vol 18 (2) ◽  
pp. 270 ◽  
Author(s):  
J Landsberg ◽  
J Stol
Keyword(s):  
Vegetation Type ◽  
New South ◽  
Ground Cover ◽  
Tree Cover ◽  
Vegetation Types ◽  
Vegetative Cover ◽  
Large Herbivores ◽  
Grazing Impacts ◽  
South Wales

The densities and distributions of sheep, kangaroos and feral goats were assessed from extensive dung surveys following dry, moderate and green seasons in three large paddocks in the wooded rangelands of north-westem New South Wales. Densities of sheep (21 9nanimals/km2) were around the long-term district average. Densities of goats (24 animals/km2) were often higher than sheep. Densities of kangaroos (1 1 animals/km2) were usually much lower than either sheep or goats. Animal density was usually related to vegetative cover (ground cover for sheep and kangaroos, shrub and tree cover for goats), but there were also differences among paddocks. Distribution of kangaroos showed the most differentiation according to vegetation type, with densities being consistently high on a small area of alluvial grassland and very low in the paddock with no alluvial plains and the lowest levels of ground cover. The distributions of sheep and goats were correlated in the dry season and both species showed similar ranges in preferences for different vegetation types. Of the large herbivores present in these woody rangelands, kangaroos were the most selective in terms of the vegetation types they grazed, and goats were the least selective. Because their grazing activities are focussed on alluvial grasslands, kangaroos have potential to degrade this locally uncommon vegetation type. However, the densities of kangaroos in other, more widespread, vegetation types were uniformly low. Goats were frequently the most abundant large herbivores present and were also the least selective. Therefore goats probably have the greatest potential for causing widespread grazing impacts across much of these woody rangelands.

Wool production, ground cover and botanical composition of pastures grazed by Merino wethers in central western New South Wales. 2. Barrel medic pasture

1973 ◽  
Vol 13 (64) ◽  
pp. 510 ◽  
Author(s):  
H Brownlee
Keyword(s):  
Agricultural Research ◽  
New South ◽  
Ground Cover ◽  
Additional Treatment ◽  
Research Station ◽  
Botanical Composition ◽  
Stocking Rate ◽  
Barrel Medic ◽  
South Wales ◽  
Pasture Area

Two grazing experiments were performed between 1965 and 1969 at the Agricultural Research Station, Condobolin, to determine the carrying capacity of Jemalong barrel medic (Medicago truncatula) pasture. In each experiment the pasture was set stocked with Merino wethers at 3.1, 4.1 and 6.2 ha-1. An additional treatment stocked at 6.2 ha-1 was included in which two-thirds of the pasture area was saved during autumn or periods of feed shortage while stock were confined to the other one-third. In both experiments the pasture supported 3.1 wethers ha-1 under set stocking for three years with little supplementary feeding and regenerated successfully each year. No major changes in botanical composition were recorded, and Jemalong medic remained the major component of the pasture. Autumn saving at 6.2 ha-1 mitigated the effects of the high stocking rate on both animal and pasture, but did not result in worthwhile animal production increases.

Effect of time of application of herbicides on the long-term control of St. John's wort (Hypericum perforatum var. augustifolium)

1979 ◽  
Vol 19 (101) ◽  
pp. 746 ◽  
Author(s):  
MH Campbell ◽  
JJ Dellow ◽  
AR Gilmour
Keyword(s):  
Hypericum Perforatum ◽  
New South ◽  
Ground Cover ◽  
Experimental Period ◽  
Time Of Application ◽  
St John’S Wort ◽  
St John's Wort ◽  
South Wales ◽  
Long Term Effect

The effect of time of application of herbicides on the long-term control of St. John's wort was investigated at Tuena, New South Wales. The herbicides used were: 2,4-D, 2,4,5-T, 2,4-D -i- 2,4,5-T, picloram + 2,4-D, and glyphosate. Each of these was applied in February, May, August and November, 1976, and regrowth of wort monitored until February 1978. The percentage ground cover of unsprayed St. John's wort varied between 75% and 85% over the experimental period. Initially all herbicides reduced the ground cover of St. John's wort from over 75% to less than 15%. Thereafter the regrowth of wort depended on the long-term effect of the herbicides. At the final assessment in February 1978, the most effective herbicide treatments were: from the February and May applications, glyphosate and picloram + 2,4-D; from the August application, picloram + 2,4-D; and from the November application, picloram + 2,4-D, 2,4-D + 2,4,5-T and 2,4-D.

Grazing studies of a Hyparrhenia hirta (Coolatai grass) pasture in northern New South Wales

2005 ◽  
Vol 45 (12) ◽  
pp. 1603 ◽  
Author(s):  
G. M. Lodge ◽  
L. H. McCormick ◽  
S. Harden
Keyword(s):  
New South ◽  
Basal Area ◽  
Ground Cover ◽  
Experimental Period ◽  
Stocking Rate ◽  
Soil Microbial ◽  
Basal Cover ◽  
South Wales ◽  
Heavy Grazing ◽  
Stocking Rates

Hyparrhenia hirta (L.) Stapf (Coolatai grass) has invaded large areas of grazed native grasslands on the North-West Slopes of New South Wales (NSW) and is widespread along roadsides and travelling stock routes. It is commonly regarded as an invasive, weedy species with low forage value when it is tall and rank, but may be more palatable when kept short, green and leafy. A study (1990–2001) of a naturalised stand of Coolatai grass in the Manilla district of northern NSW examined its herbage mass (kg DM/ha), persistence (basal cover %), and grazing value under 2 contrasting grazing treatments: pastures that had either large amounts of dry, unpalatable herbage [light grazing at 5 dry sheep equivalents (DSE)/ha] or were short, green and leafy (strategic heavy grazing at a stocking rate of 37 DSE/ha). Effects of pre-grazing treatments (slashing, burning, and no defoliation) were also examined and data (litter mass, plant basal area, ground cover, and soil and litter microbial carbon and nitrogen) collected to assess the long term sustainability of these grazing systems. Sheep grazed the light grazing treatment for about 34% of the experimental period, with the strategic heavy grazing treatment being grazed for about 7% of the time. Over the experimental period this equated to 6752 DSE grazing days/ha for the light grazing treatment compared with 10 120 DSE for the heavy grazing treatment. Herbage mass in the heavy grazing treatment declined to <1000 kg DM/ha within 6 months of the start of grazing and remained below this level until December 1998 when stocking rates were switched (i.e. plots previously grazed at low stocking rate were subjected to the heavier rate and vice versa). In contrast, mean herbage mass in the light grazing treatment was generally >3000 kg DM/ha from November 1990–98, but a high proportion of this was dead standing material that carried over from season to season. Mean Coolatai grass basal cover was 9.5% in November 1990, increasing over time to about 25% in both grazing treatments by December 2000. Coolatai grass herbage accumulation was highly seasonal, ranging from as high as 70 kg DM/ha.day in summer to 0 in winter. In both grazing treatments, forage quality was low for both green and dead material, with mean crude protein being 6.0 (green) and 3.4% (dead). Digestible dry matter values ranged from 41 to 62% (green) and 32 to 51% (dead) and mean metabolisable energy values were 7 (green) and 5.3 MJ/kg DM (dead). After 8 years, the heavy grazing treatment had lower (P<0.05) litter mass, ground cover, plant basal area and soil microbial C and N levels than the light grazing treatment, but switching of the stocking rates restored most indicators, except the soil microbial values.

Assessing the Impacts of Logging on Reptiles and Frogs in the Montane Forests of Southern New South Wales.

1996 ◽  
Vol 23 (4) ◽  
pp. 495 ◽  
Author(s):  
R Goldingay ◽  
G Daly ◽  
F Lemckert
Keyword(s):  
Management Practices ◽  
New South ◽  
New South Wales ◽  
Habitat Type ◽  
Regional Survey ◽  
Montane Forests ◽  
South Wales ◽  
Reptile Species ◽  
Frog Species ◽  
The Impact

This study describes an assessment of the medium-term effects of selection logging on the reptiles and frogs in the montane forests near Queanbeyan, New South Wales. A total of 15 reptile and two frog species was detected across 20 fixed-area plots that were selected according to broad forest type and logging history. Reptile species richness was not significantly different among the different habitat treatments. Total reptile abundance was significantly higher on logged plots, but was not influenced by forest moisture type. Individual analyses for five lizard species (accounting for 84% of all data) showed that several species (Eulamprus tympanum, E. heatwolei and Pseudemoia spenceri) had significantly greater abundances on the logged plots than on the unlogged plots, while two species (Nannoscincus maccoyi and Niveoscincus coventryi) did not differ significantly in their abundances across treatments. Thus, none of these species (which included arboreal, terrestrial and fossorial species) appeared to be adversely affected by past logging practices. Insufficient data on frogs were obtained for analysis. An additional 26 species (13 reptile and 13 frog species) were recorded during a regional survey involving 57 sites. Only two frog species were detected at more than 10 sites, illustrating the difficulty in obtaining data to determine whether logging has any impact on frog populations. Snakes are similarly difficult to assess: 13 snakes from six species were detected in this study. It is concluded that (i) the most abundant reptile species were not adversely affected by past logging, and (ii) many species of herpetofauna were patchy in their distribution across the study area, preventing resolution of the influence of habitat type or disturbance. The difficulty in collecting quantitative data on frogs and snakes confirms the importance of surveys that target endangered frog and snake species so that protective buffer zones can be delineated. Further research is required on these groups to assess the impact of forest management practices.

The impact of rabbits on a grazing system in eastern New South Wales.1. Ground cover and pastures

2002 ◽  
Vol 42 (7) ◽  
pp. 909 ◽  
Author(s):  
J. D. Croft ◽  
P. J. S. Fleming ◽  
R. van de Ven
Keyword(s):  
New South ◽  
New South Wales ◽  
Subterranean Clover ◽  
Ground Cover ◽  
Bare Soil ◽  
South Wales ◽  
Pasture Degradation ◽  
The Impact ◽  
The Relationship ◽  
Density Treatment

Although there have been a number of studies that have examined the effects of rabbits on pasture, the relationship between rabbit density and pasture degradation caused by rabbits has never been quantified. An experiment was conducted at Cowra, New South Wales, from October 1984 to October 1987, to determine the impact various densities of rabbits have on pasture composition, indices of pasture biomass and ground cover. Using plots set stocked with the equivalent of 8 sheep/ha (the district average) and 4 densities of rabbits as treatments, 0,�24, 48 and 72 rabbits/ha, the consequences of rabbit grazing were investigated.Pasture composition changed with season, year and rabbit density. Cumulative effects were also evident. Rabbits severely depleted improved pastures of legumes (subterranean clover particularly), with grass cover increasing proportionate to rabbit density. In the final year of the experiment, the rabbit-free treatment had 31% legumes and 25.2% grasses, whereas the highest rabbit density treatment had 6.2% legumes and 47.4% grasses. Indices of pasture biomass were highest in the zero rabbits/ha treatment and lowest in the 72 rabbits/ha treatment. More bare soil was exposed in the highest rabbit density treatment. Once seasonal and year effects were accounted for, the relationship between rabbit density and percentage damage was positive.

Grass seed contamination of the wool and carcases of sheep grazing natural pasture on the north-western slopes of New South Wales

1981 ◽  
Vol 21 (111) ◽  
pp. 382 ◽  
Author(s):  
GM Lodge ◽  
BA Hamilton
Keyword(s):  
New South ◽  
Experimental Period ◽  
Sheep Grazing ◽  
Grass Seed ◽  
The North ◽  
South Wales ◽  
Natural Pasture ◽  
Hordeum Leporinum ◽  
The Mean

A group of six-month-old Merino wether weaners was grazed from January to July 1977 on a natural pasture containing seeds of wiregrass (Aristida ramosa), corkscrew grass (Stipa variabilis), barley grass (Hordeum leporinum) and burrs of Medicago minima. The sheep were then removed from the natural pasture, shorn and grazed for a further 23 months on lucerne and oats pastures that were free of grass seed. The number and species of grass seeds and burrs in the wool, hide and carcases were measured to determine the levels of seed and burr contamination and the long-term fate of seeds entering the carcase. The highest number of seeds in the wool, hide and carcase of sheep grazing natural pasture were those of wiregrass. Numbers of seeds of this species per 100 cm2 ranged from 85 to 651 in the wool, 43 to 159 in the hide, and 1 to 8 in the carcase. Most of the grass seeds in the wool were located on the stomach and shoulders, while most of the burrs were on the hind legs and stomach. Percentages of grass seed were highest about the stomach area and shoulders for the hide and carcase, respectively. After the sheep were removed from the natural pasture, and grazed on lucerne and oats pastures for 23 months, the mean grass seed contents decreased by 81% in the hide and 83% in the carcase. Wiregrass seeds were the only seeds that penetrated the hide and remained in the carcase. Numbers of contaminating seeds decreased most rapidly within 6 months of the sheep being removed from the natural pasture. Over the experimental period no seed-free hides or carcases were observed.

Temporal Decline of 1080 Within Meat Baits Used for Control of Wild Dogs in New South Wales.

1991 ◽  
Vol 18 (6) ◽  
pp. 729 ◽  
Author(s):  
PJS Fleming ◽  
RW Parker
Keyword(s):  
New South ◽  
Short Term ◽  
South Wales ◽  
Residual Level ◽  
Term Trial ◽  
Short And Long Term ◽  
The Mean ◽  
Rate Of Decline ◽  
Wild Dogs

Short- and long-term trials were conducted to determine the rate of decline of 1080 (sodium fluoroacetate) in meat baits used for poisoning wild dogs. Baits were injected with 0.2 ml of standard 1080 solution (nominal dose of 6.00 mg of pure 1080 per bait) and placed in the field. In the long-term trial, 10 baits were collected at 7 intervals between 3 h and 226 days, and analysed for residual 1080 by liquid chromatography. The recoverable 1080 content declined greatly over the first 48 days, although at 226 days all 10 baits retained some 1080. By 42.4 days the mean residual level of 1080 in the baits was predicted to be less than the theoretical LD99 for wild dogs. At the time of distribution, baits contained less than the LD50 for an average-sized eastern quoll. The LD99 for domestic cattle-dogs was predicted to be still present in baits at 72.9 days. Loss of 1080 from these baits was not correlated with rainfall, temperature or humidity. In the short-term trial, 10 baits were collected at 11 intervals up to 200 h. The recoverable 1080 content decreased by 3.09 mg (61% of the injected dose) within the first hour after injection and declined to a low of 2.70 mg at hour 50. The level of recovered 1080 then rose to 73% of the injected dose at hour 150.

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