Persistence and productivity of perennial ryegrass in sheep pastures in south-western Victoria: a review

2001 ◽  
Vol 41 (1) ◽  
pp. 117 ◽  
Author(s):  
R. A. Waller ◽  
P. W. G. Sale

Loss of perennial ryegrass (Lolium perenne L.) from the pasture within several years of sowing is a common problem in the higher rainfall (550–750 mm annual rainfall), summer-dry regions of south-eastern Australia. This pasture grass came to Australia from northern Europe, where it mostly grows from spring to autumn under mild climatic conditions. In contrast, the summers are generally much drier and hotter in this region of south-eastern Australia. This ‘mismatch’ between genotype and environment may be the fundamental reason for the poor persistence. There is hope that the recently released cultivars, Fitzroy and Avalon, selected and developed from naturalised ryegrass pastures in south-eastern Australia for improved winter growth and persistence will improve the performance of perennial ryegrass in the region. Soon-to-be released cultivars, developed from Mediterranean germplasm, may also bridge the climatic gap between where perennial ryegrass originated and where it is grown in south-eastern Australia. Other factors that influence perennial ryegrass persistence and productivity can be managed to some extent by the landholder. Nutrient status of the soil is important since perennial ryegrass performance improves relative to many other pasture species with increasing nitrogen and phosphorus supply. It appears that high soil exchangeable aluminium levels are also reducing ryegrass performance in parts of the region. The use of lime may resolve problems with high aluminium levels. Weeds that compete with perennial ryegrass become prevalent where bare patches occur in the pasture; they have the opportunity to invade pastures at the opening rains each year. Maintaining some herbage cover over summer and autumn should reduce weed establishment. Diseases of ryegrass are best managed by using resistant cultivars. Insect pests may be best managed by understanding and monitoring their biology to ensure timely application of pesticides and by manipulating herbage mass to alter feed sources and habitat. Grazing management has potential to improve perennial ryegrass performance as frequency and intensity of defoliation affect dry matter production and have been linked to ryegrass persistence, particularly under moisture deficit and high temperature stress. There is some disagreement as to the merit of rotational stocking with sheep, since the results of grazing experiments vary markedly depending on the rotational strategy used, climate, timing of the opening rains, stock class and supplementary feeding policy. We conclude that flexibility of grazing management strategies is important. These strategies should be able to be varied during the year depending on climatic conditions, herbage mass, and plant physiology and stock requirements. Two grazing strategies that show potential are a short rest from grazing the pasture at the opening rains until the pasture has gained some leaf area, in years when the opening rains are late. The second strategy is to allow ryegrass to flower late in the season, preventing new vegetative growth, and perhaps allowing for tiller buds to be preserved in a dormant state over the summer. An extension of this strategy would be to delay grazing until after the ryegrass seed heads have matured and seed has shed from the inflorescences. This has the potential to increase ryegrass density in the following growing season from seedling recruitment. A number of research opportunities have been identified from this review for improving ryegrass persistence. One area would be to investigate the potential for using grazing management to allow late development of ryegrass seed heads to preserve tiller buds in a dormant state over the summer. Another option is to investigate the potential, and subsequently develop grazing procedures, to allow seed maturation and recruitment of ryegrass seedlings after the autumn rains.

Soil Research ◽  
2017 ◽  
Vol 55 (8) ◽  
pp. 799 ◽  
Author(s):  
Susan E. Orgill ◽  
Jason R. Condon ◽  
Mark K. Conyers ◽  
Stephen G. Morris ◽  
Brian W. Murphy ◽  
...  

In the present field survey, 72 sites were sampled to assess the effect of climate (Monaro, Boorowa and Coleambally regions) and parent material (Monaro region only; basalt and granite) on soil organic carbon (OC) under perennial pastures. In the higher-rainfall zone (Monaro and Boorowa; >500mm mean annual rainfall), OC stocks under introduced and native perennial pastures were compared, whereas in the lower-rainfall zone (Coleambally; <500mm mean annual rainfall) OC stocks under crops and pastures were compared. Carbon fractions included total OC (TOC), particulate OC (POC), resistant OC (ROC) and humic OC (HUM). Higher OC stocks were associated with higher spring and summer rainfall and lower annual temperatures. Within a climatic zone, parent material affected the stock of OC fractions in the 0–30cm soil layer. Within a climatic zone, when grouped by parent material, there was no difference in OC stock with vegetation type. There were significant correlations between soil factors associated with parent material and OC concentration, including negative correlations between SiO2 and HUM (P<0.05) and positive correlations between cation exchange capacity and TOC, POC and ROC (P<0.01). TOC was also positively correlated with total nitrogen (N) and available sulfur (S; P<0.05), indicating organic matter in soil is important for N and S supply for plant production in the studied regions, and vice versa. Although ensuring adequate available S may increase OC stocks in south-eastern Australia, the large stock of OC in the soil under perennial pastures, and the dominating effect of climate and parent material on this stock, may mean that modest increases in soil OC due to management factors go undetected.


2019 ◽  
Vol 243 ◽  
pp. 107614 ◽  
Author(s):  
Khageswor Giri ◽  
Kohleth Chia ◽  
Subhash Chandra ◽  
Kevin F. Smith ◽  
Clare M. Leddin ◽  
...  

1954 ◽  
Vol 5 (3) ◽  
pp. 448 ◽  
Author(s):  
RG Downes

A theory is presented suggesting that during the Recent Arid Period the rainfall was approximately half that of the present day and enabled cyclic salt to be accumulated in areas in south-eastern Australia, where it does not 'accumulate at present. The salinization and subsequent desalinization during the wetter conditions since the Arid Period have operated with varying degrees of intensity to produce solods, solodic and solonized soils over large areas. However, irrespective of the degree of intensity, some of the pre-Arid soils because of their chemical or physical properties have been able to resist these processes and remain unaffected. Five "pedogenetic zones" have been defined according to the degrees of intensity with which the salinization and desalinization processes are thought to have operated, and it is found that soil distribution and morphology is correlated with these defined zones. The zone in which the effect has been most intense has an average annual rainfall at present of between 20 and 30 in., and the most widespread soils, those formerly called red and yellow podzolics, are solodic soils and solods. The theory provides a reasonable explanation for the anoxalous distribution of soils within the "podzol" zone where those showing the greatest degree of horizon differentiation (solods and solodic soils) occur in the driest parts. In addition, the postulated processes for the formation of the soils provide a reason why molybdenum deficiency is so common on these soils in zone 3.


2012 ◽  
Vol 63 (4) ◽  
pp. 389 ◽  
Author(s):  
R. Thapa ◽  
D. R. Kemp ◽  
M. L. Mitchell

Recruitment of new perennial grass plants within existing grassland ecosystems is determined by seed availability, suitable microsites, nutrients and climatic conditions, water and temperatures. This paper reports on the development of criteria to predict recruitment events using modelled soil moisture conditions associated with recruitment of species in five field experiments at Orange (Phalaris aquatica), Trunkey Creek (Austrodanthonia spp.), and Wellington (Bothriochloa macra) in central New South Wales, Australia, and the frequency of those conditions during the past 30 years. Recruitment events were recorded when a rainfall event (median 68 mm across the three sites) kept the surface volumetric soil moisture (0–50 mm) above the permanent wilting point for at least 15 continuous days, allowing for, at most, two ‘dry days’ in between. A key finding from our study is that rainfall events creating favourable soil moisture conditions for seedling emergence typically occurred in the second half of February, sometimes extending to early March. Previously it was thought that recruitment would more likely occur through autumn, winter, and spring when rainfall in southern Australia is more reliable. The 30 years’ data (1975–2004) showed that the P. aquatica site had a median of 20 continuous moist days each year in February–March, whereas, there were 16 and 10 days for the Austrodanthonia and B. macra sites, respectively. The probabilities of exceeding seven or 15 continuous days of moist surface soil were 98% and 78% at the P. aquatica site, 91% and 49% at the Austrodanthonia site, and 73% and 30% at the B. macra site, and indicated that some recruitment is possible in most years. These analyses were extended to several sites across New South Wales, Victoria, and Tasmania to estimate the frequency with which recruitment could occur within natural swards. Across these sites, the probabilities of exceeding seven continuous days of soil moisture were >55% and of exceeding 15 continuous days were lower, which showed that suitable climatic conditions exist during late summer–early autumn across south-eastern Australia for a recruitment event to occur. Future research may show that the criteria developed in this paper could have wider regional application.


Soil Research ◽  
2016 ◽  
Vol 54 (5) ◽  
pp. 512 ◽  
Author(s):  
Guangdi D. Li ◽  
Mark K. Conyers ◽  
Graeme D. Schwenke ◽  
Richard C. Hayes ◽  
De Li Liu ◽  
...  

Dryland cereal production systems of south-eastern Australia require viable options for reducing nitrous oxide (N2O) emissions without compromising productivity and profitability. A 4-year rotational experiment with wheat (Triticum aestivum L.)–canola (Brassica napus L.)–grain legumes–wheat in sequence was established at Wagga Wagga, NSW, Australia, in a semiarid Mediterranean-type environment where long-term average annual rainfall is 541mm and the incidence of summer rainfall is episodic and unreliable. The objectives of the experiment were to investigate whether (i) tillage increases N2O emissions and (ii) nitrogen (N) application can improve productivity without increasing N2O emissions. The base experimental design for each crop phase was a split-plot design with tillage treatment (tilled versus no-till) as the whole plot, and N fertiliser rate (0, 25, 50 and 100kgN/ha) as the subplot, replicated three times. This paper reports high resolution N2O emission data under a canola crop. The daily N2O emission rate averaged 0.55g N2O-N/ha.day, ranging between –0.81 and 6.71g N2O-N/ha.day. The annual cumulative N2O-N emitted was 175.6 and 224.3g N2O-N/ha under 0 and 100kgN/ha treatments respectively. There was no evidence to support the first hypothesis that tillage increases N2O emissions, a result which may give farmers more confidence to use tillage strategically to manage weeds and diseases where necessary. However, increasing N fertiliser rate tended to increase N2O emissions, but did not increase crop production at this site.


2003 ◽  
Vol 43 (10) ◽  
pp. 1211 ◽  
Author(s):  
S. G. Clark ◽  
E. A. Austen ◽  
T. Prance ◽  
P. D. Ball

Climate variability is a major constraint to farming in south-eastern Australia and one that is out of the farmers' control. However, a better understanding of long-term climate variability would be beneficial for on-farm management decisions. A series of long-term simulations were undertaken with the GrassGro decision support tool to determine the effect of climate variability on pasture and animal production at 6 locations in south-eastern Australia. The simulations ran from 89 to 119 years using daily weather records from each location. All simulations were for spring-lambing flocks of medium sized Merino ewes stocked at above-average district stocking rates, grazing well-fertilised, perennial grass–subterranean clover pastures. Annual rainfall total and, in particular, the distribution of rainfall during the year, were found to be more important than other weather variables in determining the amount of pasture grown in a year. The timing of the season opening rains (autumn break) was most important. The localities varied in their responses to climate variability, particularly in the timing of the autumn break; the pasture growth response to winter rainfall; and the relationship between rainfall and animal production.


2005 ◽  
Vol 45 (4) ◽  
pp. 369 ◽  
Author(s):  
P. M. Dowling ◽  
D. R. Kemp ◽  
P. D. Ball ◽  
C. M. Langford ◽  
D. L. Michalk ◽  
...  

Declining grassland productivity is a major concern in southern temperate Australia. Continuous grazing is thought to be a primary contributor to this decline, which is associated with the loss of perennial grasses. Landholders are evaluating grazing management strategies that might curb the loss of perennials and increase long-term productivity. This study reports on a comparison between continuous grazing and time-control grazing with sheep and cattle using a paired-paddock design at 5 locations in south-eastern Australia (lat. 30–42°S) over 6 years (1994–99). Pasture herbage mass, grassland species composition and basal cover of perennial grasses were assessed at 6-monthly intervals. Species abundance data were analysed by ANOVA, ordination (multi-dimensional scaling) and splining procedures to assess comparative trends between the 2 management treatments at each site. Species were categorised into major functional groups for analysis. Over all 5 sites there were few consistent differences between management treatments (continuous grazing v. time-control grazing). Basal cover was greater on the time-control grazing management compared with continuous grazing for most of the experimental period at 3 sites, but the initial values were also greater, resulting in a non-significant management × time interaction. Based on this study, we conclude that there was no apparent medium-term benefit of a multi-paddock rotational (time-control grazing) grazing system over continuous grazing for encouraging and maintaining a favourable botanical composition. The benefits for land managers from employing systems such as time-control grazing may accrue through other mechanisms. The study also highlights some of the difficulties with conducting on-farm paired-paddock research.


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