Sustainable grazing systems for the Central Tablelands of New South Wales. 4. Soil water dynamics and runoff events for differently-managed pasture types

2006 ◽  
Vol 46 (4) ◽  
pp. 483 ◽  
Author(s):  
J. D. Hughes ◽  
I. J. Packer ◽  
D. L. Michalk ◽  
P. M. Dowling ◽  
W. McG. King ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Soil Water ◽  
New South ◽  
New South Wales ◽  
Ground Cover ◽  
Environmental Data ◽  
Quality Data ◽  
Water Runoff ◽  
South Wales ◽  
Management Factors

Soil water, runoff amount and quality, pasture production and environmental data were measured for a pastoral prime lamb enterprise in the Central Tablelands of New South Wales from 1998 to 2002. There were 4 pasture treatments: fertilised and sown chicory (CH), fertilised and sown introduced pastures (SP), fertilised naturalised pastures (FN) and unfertilised naturalised pastures (UN). Two grazing management regimes, tactically grazed (TG) and continuously grazed (CG) were imposed on the SP, FN and UN treatments. The CH treatment was rotationally grazed. To compare pasture and grazing system water use, maximum soil water deficit values (SWDMax) were calculated from neutron moisture meter data. SWDMax was influenced by both environmental and management factors. Management factors that influenced SWDMax were herbage mass of perennials, degree of perenniality, and the perennial species present. Environmental factors accounted for >50% of the variation in SWDMax. Inclusion of management factors (perennial herbage mass of C3 and C4 species and percentage perennial herbage mass), accounted for an additional 16% of variation. While the influence of pasture management appears to be relatively small, importantly, management is the only avenue available to land managers for influencing SWDMax. The UNTG and all sown treatments, with greater perennial herbage mass or greater C4 herbage mass consistently produced the highest SWDMax. Runoff amount and quality data are presented for ground cover percentages which generally exceeded 80% for the experimental period. Runoff as a proportion of rain received during the experiment was <3%. Environmental factors explained 47% of variation in runoff, while pasture herbage mass and ground cover percentage explained an additional 2% of variation. Water quality was monitored on 3 treatments (SPTG, FNTG and UNCG) for total nitrogen (N), total phosphorus (P) and total suspended solids (TST) over a 6-month period. The mean values for total N and P were below the acceptable contaminant concentration for agricultural irrigation water. An important outcome of this research is the concept of a practical Targeted Water Management Plan (TWMP) which devises a framework for optimum water usage and productivity at a landscape scale.

Surface soil water dynamics in pastures in northern New South Wales. 3. Evapotranspiration

2004 ◽  
Vol 44 (6) ◽  
pp. 571 ◽  
Author(s):  
S. R. Murphy ◽  
G. M. Lodge ◽  
S. Harden
Keyword(s):  
Soil Water ◽  
New South ◽  
New South Wales ◽  
Ground Cover ◽  
Bare Soil ◽  
Soil Evaporation ◽  
Grazing Management ◽  
South Wales ◽  
Bare Soil Evaporation ◽  
Daily Evapotranspiration

Evapotranspiration is the major component of the hydrological balance of grazed pastures on the North-West Slopes of New South Wales, representing up to 93% of annual rainfall. Nearly 80% of evapotranspiration may occur as bare soil evaporation, however, representing water not available for plant growth. Few studies have reported daily values of actual evapotranspiration for pastures, particularly in northern New South Wales. The studies reported here were conducted to measure actual evapotranspiration using an evaporation dome technique, for plots with a range of pasture, litter and ground cover. Measurements were taken in each season between autumn 2000 and autumn 2001, with both wet and dry soil surface conditions, to document the range of values that might be expected. Similar measurements were conducted in areas of natural pasture, to quantify values under grazed conditions. A range of other variables were also quantified in association with each evapotranspiration measurement; these included components of net radiant energy, atmospheric conditions, pasture physical characteristics, ground cover and soil water content. These data were used to identify the most important variables, which may be influenced by or interact with grazing management, that account for variation in daily evapotranspiration values.Hourly evapotranspiration ranged from 0.02 to 0.82 mm/h and daily values ranged from 0.2 to 7.6 mm/day, in winter to summer, respectively. Linear regression models that included variables of solar radiation, herbage mass, vapour pressure deficit and soil water content accounted for up to 93% of the variation in daily evapotranspiration values. These models predicted that high litter mass (3000 kg DM/ha) may reduce evaporation by up to 1 mm/day for wet soils, making a substantial contribution to the annual hydrological balance. A simulation study of a grazed pasture, using the Sustainable Grazing Systems Pasture Model, indicated that grazing management may influence the partitioning of transpiration and evaporation from canopy, litter and bare soil. With rotational grazing, predicted soil evaporation was lower and transpiration and canopy evaporation were higher than with continuous grazing. Hence, pastures may require different management between summer and winter, so that bare soil evaporation and canopy interception losses are minimised, to maximise stored soil water available for pasture use. Pastures with lower evaporative losses are likely to have higher productivity and sustainability.

Effects of logging and fire on small mammals in Mumbulla State Forest, near Bega, New South Wales

1987 ◽  
Vol 14 (2) ◽  
pp. 163 ◽  
Author(s):  
D. Lunney ◽  
B. Cullis ◽  
P. Eby
Keyword(s):  
Small Mammals ◽  
New South ◽  
New South Wales ◽  
Canopy Cover ◽  
Ground Cover ◽  
First Year ◽  
Severe Effect ◽  
South Wales ◽  
Antechinus Stuartii ◽  
Rattus Fuscipes

This study of the effects of logging on small mammals in Mumbulla State Forest on the south coast of New South Wales included the effects of a fire in November 1980 and a drought throughout the study period from June 1980 to June 1983. Rattus fuscipes was sensitive to change: logging had a significant impact on its numbers, response to ground cover, and recapture rate; fire had a more severe effect, and drought retarded the post-fire recovery of the population. The three species of dasyurid marsupials differed markedly in their response to ground cover, canopy cover, logging and fire. Antechinus stuartii was distributed evenly through all habitats and was not affected by logging, but fire had an immediate and adverse effect which was sustained by the intense drought. A. swainsonii markedly preferred the regenerating forest, and was not seen again after the fire, the failure of the population being attributed to its dependence on dense ground cover. Sminthopsis leucopus was found in low numbers, appeared to prefer forest with sparse ground cover, and showed no immediate response to logging or fire; its disappearance by the third year post-fire suggests that regenerating forest is inimical to the survival of this species. Mus musculus showed no response to logging. In the first year following the fire its numbers were still very low, but in the next year there was a short-lived plague which coincided with the only respite in the 3-year drought and, importantly, occurred in the intensely burnt parts of the forest. The options for managing this forest for the conservation of small mammals include minimising fire, retaining unlogged forest, extending the time over which alternate coupes are logged and minimising disturbance from heavy machinery.

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.

Establishing surface-sown pastures in a Poa labillardieri-Themeda australis association

1986 ◽  
Vol 26 (3) ◽  
pp. 331 ◽  
Author(s):  
MH Campbell ◽  
MJ Keys ◽  
RD Murison ◽  
JJ Dellow
Keyword(s):  
Festuca Arundinacea ◽  
New South ◽  
New South Wales ◽  
Ground Cover ◽  
Cost Effective ◽  
Phalaris Aquatica ◽  
South Wales ◽  
Before And After

The effects of time and rate of application of glyphosate, 2,2-DPA and tetrapion on Poa labillardieri and Themeda australis were measured in seven experiments carried out 55 km south of Braidwood, on the southern tablelands of New South Wales between 1980 and 1982. In an eighth experiment (1981) and in a 35-ha demonstration (1983), at the same site, the effects of applying herbicides (before and after the autumn break) and surface-sowing Phalaris aquatica, Festuca arundinacea and Trifiolium repens with fertiliser on the control of P. labillardieri were ascertained. All three herbicides proved effective in reducing the ground cover of P. labillardieri from applications at any time of the year. For T. australis, tetrapion proved effective when applied at any time of the year, while glyphosate and 2,2-DPA were effective in all seasons except winter. Glyphosate at rates between 0.72 and 1.44 kg/ha a.i. was more cost effective than 2,2-DPA (11.1 kg/ha a.i.) and tetrapion (3.75 kg/ha a.i.). Best establishment and development of sown grasses and legumes was attained by applying herbicides after the autumn break but before heavy frosts, and then surface-sowing 1-3 months later. Control of P. labillardieri was best where P. aquatica and F. arundinacea established most densely.

Effect of gypsum on vertisols of the Gwydir Valley, New South Wales. 1. Soil properties and wheat growth

1989 ◽  
Vol 29 (1) ◽  
pp. 51 ◽  
Author(s):  
DC McKenzie ◽  
HB So
Keyword(s):  
Soil Properties ◽  
Soil Water ◽  
New South ◽  
New South Wales ◽  
Nitrogen Deficiency ◽  
Crop Productivity ◽  
Plant Response ◽  
Crown Rot ◽  
Soil Water Storage ◽  
South Wales

The effect of gypsum on the properties and crop productivity of 6 contrasting vertisols of the Gwydir Valley, New South Wales was investigated in 1978 and 1979. These soils are often used for dryland wheat production, although crop growth is generally restricted by their structural instability. In 2 of the soils used in our study, the surface aggregates were sodic and dispersive (poor soils), 2 were relatively stable when wetted (good soils), whilst the other 2 soils had surface aggregates that were intermediate in behaviour (intermediate soils). The effects of added gypsum at 4 rates (0, 2.5, 5.0 and 7.5 t ha-1) on soil water profiles, soil properties and the growth of wheat were monitored over a 2 year period. Dryland wheat grain yields were increased by as much as 230% following the application of gypsum. Benefits were most pronounced on clays with sodic topsoils, a high water-holding capacity and adequate nutrition; plant response to gypsum on nearby soils with non-dispersive surfaces was less pronounced. Yield increases were associated with better seedling establishment, greater tiller production, increased grain weight, and lower incidence of 'Crown Rot' disease. Plant response to gypsum was related to improved water penetration into the soil, allowing greater storage of water in the subsoil, rather than loss via evaporation and possibly runoff. Increases as high as 137% in the soil water storage to a depth of 1.2 m were observed. Crop performance was also strongly influenced by rainfall, time of sowing and weed control. Where nitrogen and, to a lesser extent, phosphorus, were deficient in gypsum-treated soil, they had to be added before the extra soil water could be utilised effectively by wheat. On the lighter textured clays, gypsum appeared to aggravate nitrogen deficiency, apparently because of enhanced leaching.

Effects of continuous and seasonal grazing strategies on the herbage mass, persistence, animal productivity and soil water content of a Sirosa phalaris - subterranean clover pasture, North-West Slopes, New South Wales

2003 ◽  
Vol 43 (6) ◽  
pp. 539 ◽  
Author(s):  
G. M. Lodge ◽  
S. R. Murphy ◽  
S. Harden
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
New South ◽  
New South Wales ◽  
Subterranean Clover ◽  
Animal Production ◽  
North West ◽  
South Wales ◽  
Continuous Grazing

An experimental site was established in 1997 on the North-West Slopes of New South Wales to further investigate the use of strategic grazing management to improve the persistence of phalaris (Phalaris aquatica cv.�Sirosa) and subsequent effects on animal production and soil water content. The pasture was sown in 1992 to Sirosa phalaris, subterranean clover (Trifolium subterraneum var. subterraneum cv. Seaton Park) and lucerne (Medicago sativa cv. Aurora). Four grazing treatments were applied in a randomised 3-replicate design. Treatments consisted of continuous grazing at 12.3 sheep/ha (C12 or control); continuous grazing at 6 sheep/ha (C6), and 2� spring and autumn strategies of either resting from grazing for 6 weeks in each season (SAR0), or reducing stocking rate from 12.3 to 4.0 sheep/ha (SAR4). Despite annual applications of fertiliser and high clover content, Sirosa phalaris herbage mass in plots continuously grazed at 12.3 sheep/ha declined from a mean of 3300 kg DM/ha in spring 1997 to < 700 kg DM/ha by May 1998. At the end of the study (February 2001), Sirosa mean herbage mass in these plots was 670 kg DM/ha and lower (P < 0.05) than for the other treatments (mean value 5400 kg DM/ha). These marked changes in herbage mass, and the degradation of the Sirosa-based pasture to an annual pasture by continuous grazing at 12.3 sheep/ha, were not generally reflected in either short-term animal production or substantial differences in soil water content. Wool production (kg/head) was not significantly different among treatments each year. Compared with continuous grazing at 12.3 sheep/ha, sheep liveweights were higher (P < 0.05) in plots continuously grazed at 6.1 sheep/ha from November 1997 to February 1999. However, from February 1999 to 2001, sheep liveweights in the 2 treatments with the highest Sirosa phalaris content were lower (P < 0.05) than those continuously grazed at 12.3 sheep/ha. Only the soil water content for the C6 and SAR4 treatments at 0–30�cm was significantly different to the control treatment, but the differences were predicted to be < 2.5 mm/year. In the root zone (0–90 cm), mean soil water content ranged from 159 to 309 mm (mean 220 mm), while plant available water (soil water content – soil water content at –1500 kPa) was a mean of 79 mm, ranging from 11 to 168 mm.

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