Effect of environmental factors on the growth of grazed pasture in south-western Victoria

2006 ◽  
Vol 46 (4) ◽  
pp. 545 ◽  
Author(s):  
H. A. Birrell ◽  
R. L. Thompson
Keyword(s):  
Climatic Factors ◽  
Subterranean Clover ◽  
Botanical Composition ◽  
Stocking Rate ◽  
Daily Growth ◽  
Pasture Production ◽  
Grazed Pasture ◽  
Herbage Yield ◽  
Western Victoria ◽  
Stocking Rates

This paper presents work from several studies on pasture production that were conducted in south-west Victoria at the Pastoral Research Institute, Hamilton. The frequency with which pasture growth commenced for each week of autumn in the years from 1965 to 1991 was assessed. The median period for the commencement of growth was in the third week of March (although the average date was March 27). Autumn data from several trials conducted over 3 decades were collated and analysed. A relationship between the grazed pasture yield (average of stocking rates plots) at the end of autumn and the rainfall showed that 200 mm of rainfall in the 3 months to the end of May was optimal while higher rainfall depressed the growth. The average daily growth rates of introduced pasture (perennial rye grass, Lolium perenne L. cv. Victorian, phalaris, Phalaris aquatica L. cv. Australian, subterranean clover Trifolium subterranneum L. and volunteer species) were measured in 2- and 4-week growth periods (G 2 and G 4, kg DM/ha.day) for the seasonal growth cycles over 4 years (1980–84 except 1983) when grazed by Merino wether sheep at stocking rates of 10, 13 or 18 sheep/ha. The rainfall throughout the study was lower than normal. Although differences in the animal performance between the stocking rates were only small, at the low stocking rate capeweed (Arctotheca calendula L.) in patches became the major component of the sward. Greater variation in G 2 than in G 4 indicated that growth responded quickly to current environmental conditions. A nonlinear regression accounted for 74% of the variance in G 2 when related to the 3 climatic factors of daylength, soil temperature at 10 cm depth and the soil moisture to a depth of 10 cm, and a plant factor of green herbage yield. The 26 % of unaccounted variance appears to be associated with an effect of stocking rate, possibly botanical composition. The botanical composition was not continuously monitored hence the only sward character included in the investigation was herbage yield. Comparison of the patterns of pasture growth from different latitudes indicated that while the growth pattern in south-western Victoria is erratic, it is intermediary between Mediterranean and temperate pasture types. Understanding this aspect has implications for improving the efficiency of animal production in this environment.

A comparison of levels of production and profit from grazing Merino ewes and wethers at various stocking rates in northern Victoria

1980 ◽  
Vol 20 (104) ◽  
pp. 296 ◽  
Author(s):  
DH White ◽  
BJ McConchie ◽  
BC Curnow ◽  
AH Ternouth
Keyword(s):  
Subterranean Clover ◽  
Early Spring ◽  
Botanical Composition ◽  
Stocking Rate ◽  
Pasture Production ◽  
Fleece Weight ◽  
Sheep Production ◽  
Rate Of Decline ◽  
One Year ◽  
Stocking Rates

Merino wethers and breeding ewes were grazed at various stocking rates on an annual pasture in the sheep-wheat zone of Northern Victoria from 1966 to 1973. There was considerable variation between years in botanical composition, the incidence of subterranean clover in the pasture plots varying by up to 80 percentage units between years. Total pasture production was measured in one plot during the last 4 years of the experiment, varying from 2.1 t ha-1 in the drought year (325 mm rain) of 1972, to 8.8 t ha-1 in the higher rainfall (883 mm) year of 1973. The large year-to-year variations in pasture production and botanical composition were reflected in differences between years in sheep production at various stocking rates. Wethers produced about 20% more wool than breeding ewes grazing at the same stocking rate, providing no supplements were fed. August-lambing ewes either lost weight in early spring or gained weight more slowly than wethers of the same age and flock background. The consequence of this was that maximum weights of ewes were consistently about 10 kg less than wethers at the same stocking rate. Both ewes and wethers had similar rates of weight loss from November to March. In one year ewes at 3.7 ha-1 were fed supplements in autumn, since they were lighter than the feeding weight of 41 kg, whereas wethers stocked at 11.1 ha-1, were not. An economic analysis of the experimental data indicated that the most profitable stocking rates of Merino wethers were up to 1.7 times that of August-lambing ewes. This ratio varies with season, and is also likely to vary with changes in lambing date or environment. The most sensitive determinants of optimal stocking rate were the rate of decline of fleece weight, and lambs born relative to ewes joined, with increasing stocking rate. Sheep liveweight at time of sale could also be important.

Pasture systems to improve productivity of sheep in south-western Victoria. 1. Growth, composition, nutritive value and persistence of resown pastures

2009 ◽  
Vol 49 (8) ◽  
pp. 654 ◽  
Author(s):  
Geoffrey Saul ◽  
Gavin Kearney ◽  
Dion Borg
Keyword(s):  
Nutritive Value ◽  
Subterranean Clover ◽  
Local Environment ◽  
Perennial Grasses ◽  
Stocking Rate ◽  
Pasture Production ◽  
P Rate ◽  
The Difference ◽  
Western Victoria ◽  
Over Time

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.

Superphosphate and stocking rate effects on a native pasture oversown with Stylosanthes humilis in central coastal Queensland. 1. Pasture production

1978 ◽  
Vol 18 (95) ◽  
pp. 788 ◽  
Author(s):  
NH Shaw
Keyword(s):  
Soil Phosphorus ◽  
Total Yield ◽  
Botanical Composition ◽  
Stocking Rate ◽  
Pasture Production ◽  
Average Percentage ◽  
Heteropogon Contortus ◽  
Native Pasture ◽  
Nitrogen Concentrations ◽  
Stocking Rates

Changes in the yield, botanical composition and chemical composition of a native pasture (Heteropogon contortus dominant) oversown with S. humilis (T.S.) were measured in a grazing experiment from 1966 to 1973. The 24 treatments were factorial combinations of two sowing methods for T.S. (ground sowing into spaced cultivated strips, or aerial sowing), three levels of molybdenized superphosphate (F0 = nil ; F1 = 125 kg ha-1 annually; F2 = 250 kg ha-1 annually plus an extra 250 kg ha-1 initially) and four stocking rates. Stocking rates were gradually increased during the experiment and for the last three years overlapping ranges were used for the three fertilizer levels; the overall range was then from 0.55 to 1.65 beasts ha 1 T.S. establishment by ground sowing was much more reliable than from aerial sowing, giving twice the average percentage frequency, and this proportion was maintained over years. High fertilizer improved establishment and the best legume stands were in the high fertilizer high stocking rate treatments. Total presentation yield of pasture was increased by fertilizer and reduced by high stocking rates. Over the last two years the means for March, adjusted by regression to the overall average stocking rate of 0.98 beasts ha-1, were 31 20,4020 and 5370 kg ha-1 for F0, F1 and F2 respectively, but these yields were reduced by ca 25 per cent for an increase of 0.5 beasts ha-1. H. contortus remained dominant and its mean contribution to total yield increased from 48 per cent in 1969 to 67 per cent in 1973. This proportion was reduced by 12.8 per cent over the range from 0.55 to 1.65 beasts ha-1, but high fertilizer had the opposite effect so that differences between the extremes low stocked F0 and high stocked F2 were small. The DM percentage yield of T.S. was strongly increased by fertilizer, and, most importantly, also by high stocking rates in the presence of fertilizer. Values for F0 treatments remained below 10 per cent, but in the final year values for F1 and F2 at the highest stocking rates were 36 and 27 per cent, respectively. Despite these large changes in T.S., there was overall stability of botanical composition. Phosphorus and nitrogen concentrations in T.S. and H. contortus were increased by superphosphate but there was an overall decline in potassium concentration. Soil phosphorus levels were greatly increased

Influence of stocking rate and mixed grazing of Angora goats and Merino sheep on animal and pasture production in southern Australia. 1. Botanical composition, sward characteristics and availability of components of annual temperate pastures

2010 ◽  
Vol 50 (2) ◽  
pp. 138 ◽  
Author(s):  
B. A. McGregor
Keyword(s):  
Subterranean Clover ◽  
Botanical Composition ◽  
Stocking Rate ◽  
Bare Ground ◽  
Pasture Production ◽  
Weed Invasion ◽  
Merino Sheep ◽  
Grazed Pastures ◽  
Temperate Pastures ◽  
Angora Goats

The effects of animal species (AS; Angora goats, Merino sheep or goats and sheep mixed grazed together at ratio 1 : 1) and stocking rate (SR; 7.5, 10 and 12.5 animals/ha) on the availability, botanical composition and sward characteristics of annual temperate pastures under continuous grazing were determined in a replicated experiment from 1981 to 1984. AS and SR had significant effects on pasture availability and composition and many AS × SR interactions were detected. The pastures grazed by sheep had significantly reduced content and proportion of subterranean clover and more undesirable grasses compared with those grazed by goats. There were no differences in dry matter availabilities between goat- and sheep-grazed pastures at 7.5/ha, but at 10 and 12.5/ha goat pastures had significantly increased availabilities of green grass, dead and green clover and less weeds compared with sheep pastures. There was a significant AS × SR interaction for the density of seedlings in May following pasture germination. Between July and January, the height of pastures was greater under goats than sheep but from January to March pasture height declined more on goat-grazed than on sheep-grazed pastures. There was an AS × SR interaction for incidence of bare ground. Increasing the SR increased bare ground in pastures grazed by sheep but no change occurred on pastures grazed by goats. Changes in pasture characteristics due to increased SR were minimised on pastures grazed by goats but the grazing of sheep caused larger and faster changes and the pastures were damaged at the highest SR. Goats did not always select the same herbage material as sheep, changed their selection between seasons and were not less selective than sheep. Angora goats were flexible grazers and continually adapted their grazing behaviour to changing herbage conditions. Goat grazing led to an increase in subterranean clover, an accumulation of dead herbage at the base of the sward, reduced bare ground, taller pastures in spring and a more stable botanical composition. Mixed-grazed pasture characteristics were altered with SR. With careful management Angora goats on sheep farms may be used to manipulate pasture composition, to speed up establishment of subterranean clover, to decrease soil erosion and to reduce weed invasion.

Tactical versus continuous stocking in perennial ryegrass-subterranean clover pastures grazed by sheep in south-western Victoria. 1. Stocking rates and herbage production

2001 ◽  
Vol 41 (8) ◽  
pp. 1099 ◽  
Author(s):  
R. A. Waller ◽  
P. W. G. Sale ◽  
G. R. Saul ◽  
G. A. Kearney
Keyword(s):  
Perennial Ryegrass ◽  
Dry Matter ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Stocking Rate ◽  
Soil Fertility Status ◽  
Western Victoria ◽  
Terminal Sire ◽  
Autumn And Winter ◽  
Stocking Rates

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 year-around 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 herbage production and stocking rate are presented in this paper. Herbage production was similar between the treatments, but tactical stocking significantly increased herbage mass during the growing season (P<0.05) compared with continuous stocking. In spring each year, the herbage mass generally exceeded 3000 kg dry matter/ha in tactically stocked paddocks and averaged 500–900 kg dry matter/ha higher than the mass on continuously stocked paddocks. This enabled the year-round stocking rate to be increased by an average of 9% over the 4 years of the experiment. We considered that the stocking rates could not be further increased, despite the higher herbage mass in spring, as stock reduced the dry herbage to a low residual mass by the opening rains in autumn. In contrast, stocking rates averaged 51% higher on the upgraded pasture compared with the typical pasture over the 4 years of the experiment. This indicates that pasture improvement and soil fertility status have a much greater impact on productivity than changes to grazing method. However, tactical stocking was able to increase the sustainability of prime lamb production on upgraded pastures in a dry summer climate, by maintaining herbage cover on the paddocks over the summer–autumn period.

Effects of superphosphate fertiliser and stocking rate on the nutritive value of perennial ryegrass and subterranean clover herbage

1999 ◽  
Vol 50 (4) ◽  
pp. 537 ◽  
Author(s):  
G. R. Saul ◽  
G. A. Kearney ◽  
P. C. Flinn ◽  
C. L. Lescun
Keyword(s):  
Perennial Ryegrass ◽  
Crude Protein ◽  
Dry Matter ◽  
Nutritive Value ◽  
Subterranean Clover ◽  
Stocking Rate ◽  
Western Victoria ◽  
Stocking Rates ◽  
Infertile Soils

The effect of superphosphate fertiliser on digestible dry matter (DDM) and crude protein (CP) percentages of perennial ryegrass and subterranean clover was assessed on a long-term, grazed experiment in western Victoria. CP of both species increased significantly (3–6 units) where long-term average phosphorus (P) applications were 33 kg/ha.year compared with 1 kg/ha.year. CP of herbage was also greater on paddocks grazed at higher (9–23 ewes/ha) than lower (5–13 ewes/ha) stocking rates (1–3 units). DDM of subterranean clover significantly increased (8–10 units) with higher superphosphate applications but there was little effect on the DDM of perennial ryegrass. Long-term applications of superphosphate were associated with larger increases in both DDM and CP than if the same rate was applied in autumn of the year of measurement. For subterranean clover, 30 kg/ha of P applied to infertile soils (Olsen P 5 mg/kg) in autumn increased the DDM of herbage collected in September by only 4–6 units. The nutritive value of most volunteer pasture species also increased with higher superphosphate applications but the DDM of these species was usually inferior to perennial ryegrass. The results highlight the importance of monitoring nutritive value, pasture composition, and herbage production to quantify fully the likely effect of fertiliser applications on animal production.

Stocking rate and the superphosphate requirements of sown pasture on an acid soil

1968 ◽  
Vol 8 (30) ◽  
pp. 33 ◽  
Author(s):  
KD McLachlan
Keyword(s):  
Acid Soil ◽  
Grazing Intensity ◽  
Subterranean Clover ◽  
Growth Potential ◽  
Available Phosphorus ◽  
Similar Response ◽  
Stocking Rate ◽  
Pasture Production ◽  
Significant Difference ◽  
Stocking Rates

The response by Phalaris-subterranean clover pasture to applied nitrogen, phosphorus, and sulphur was measured at two sites on the same soil. Both sites had the same fertilizer history. For the past fifteen years the stocking rate on one site had been maintained at not less than three times that of the other. Yield responses to phosphorus were obtained at both sites. The response at the lower stocking rate was greater than that at the high stocking rate. A similar response pattern was found for nitrogen, but the difference in response between the stocking rate treatments was not significant. The pastures did not respond to sulphur. The trend was for sulphur to depress the yield at both stocking rates. The evidence suggests that less superphosphate was needed to maintain pasture production at high stocking rates than at low ones. Available phosphorus, determined chemically, increased with grazing intensity. There was no evidence that a particular soil phosphorus fraction was associated with this increase, or the lower requirement for added fertilizer. The only significant difference between grazing treatments were increases in the iron, calcium, and organic forms at the higher grazing intensity. It is probable that the present pasture response, and hence the fertilizer requirement of the soil, was influenced more by the altered growth potential of the plants under grazing, than by the effect of grazing on the soil nutrient status.

Effect of deferred autumn grazing and stocking rate of sheep on pasture production in a Mediterranean-type climate

1976 ◽  
Vol 16 (79) ◽  
pp. 181 ◽  
Author(s):  
TH Brown
Keyword(s):  
South Australia ◽  
Grazing Management ◽  
Research Centre ◽  
Botanical Composition ◽  
Stocking Rate ◽  
Pasture Production ◽  
Continuous Grazing ◽  
Wimmera Ryegrass ◽  
June July ◽  
Stocking Rates

The effect of deferred autumn grazing and stocking rate on an annual pasture was monitored for five years at Kybybolite Research Centre in the south-east of South Australia. Pasture availability, yearly production and botanical composition were measured under a series of eight stocking rates from 12.4 to 29.7 Merino wethers per hectare. Autumn deferment resulted in extra available pasture during the winter months of June, July and August. However, the continously grazed pastures reached the same level of availability as the deferred pastures in spring. By the third year of the experiment yearly pasture production irrespective of grazing management was greatly reduced at the higher stocking rates. This reduction was associated with an invasion of Poa annua and Juncus bufonius. Autumn deferment tended to favour the growth of Wimmera ryegrass at the lower stocking rates whereas continuous grazing tended to favour clover growth at these stocking rates.

The effects of sheep treading and grazing on pasture and soil characteristics of irrigated annual pastures

1979 ◽  
Vol 30 (4) ◽  
pp. 741 ◽  
Author(s):  
PA Witschi ◽  
DL Michalk
Keyword(s):  
Bulk Density ◽  
Subterranean Clover ◽  
Soil Characteristics ◽  
Combined Effect ◽  
Late Winter ◽  
Botanical Composition ◽  
Stocking Rate ◽  
Grazing Experiment ◽  
Wimmera Ryegrass ◽  
Stocking Rates

The two experiments reported examined the effects of sheep treading on pasture growth and soil characteristics on autumn-irrigated subterranean clover-Wimmera ryegrass pastures and their subsequent influence on winter production. Treading only (experiment 1) increased the bulk density of soil by 40% as the stocking rate increased from 0 to 39.2 sheep ha-1. This caused a 33% reduction in late winter production (July), the decline (675 kg ha-1) being due mainly to a reduction in the proportion of ryegrass in the pasture. The combined impacts of treading and grazing (experiment 2) proved more detrimental to subsequent pasture recovery. At the July measurement, treading reduced production by 20% when the stocking rate was increased from 0 to 19.6 sheep ha-1, while the combined effect produced a 58% loss in yield. In addition to stocking rate, the length of the pre-grazing establishment period proved critical, with greater compaction evident in plots stocked 24 h after irrigation. This compaction affected the botanical composition, significantly more ryegrass being present in compacted plots, although increased tillering was encouraged by intense defoliation at high stocking rates which intensified this effect.

Pasture production of two cultivars of Trifolium subterraneum at Kybybolite, South Australia

1992 ◽  
Vol 32 (5) ◽  
pp. 611 ◽  
Author(s):  
AD Craig
Keyword(s):  
South Australia ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Biochanin A ◽  
Stocking Rate ◽  
Seedling Density ◽  
Pasture Production ◽  
Seed Reserves ◽  
Seed Yields ◽  
Stocking Rates

Two cultivars of subterranean clover, Trikkala and Mt Barker, were continuously grazed by Merino ewes and lambs at 3 stocking rates (8, 13, and 18 ewes/ha) from 1976 to 198 1. The pastures were assessed for clover seedling density, pasture availability and composition, seed reserves, and oestrogen content. Trikkala produced consistently higher seed yields than Mt Barker, with an average yield 3.36 times that of Mt Barker by January 1981 (1178 v. 350 kg/ka). The higher Trikkala seed yields resulted in improved clover seedling densities and increased amounts of clover in the pastures. At the last assessment (8 September 1980) there was an average of 3.15 times more clover in the Trikkala pastures than in the Mt Barker pastures (469 v. 149 kg/ha). Trikkala produced more total available pasture than Mt Barker, at several samplings, because the contribution of subterranean clover to total available pasture was greater after September 1978. The formononetin, genistein and biochanin A content of both cultivars decreased with increasing stocking rate. The most consistent effects were observed in genistein content, with reductions occurring in 7 of the 11 samplings.

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