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Pasture species - persistence or productivity?

Dr. E.C. Wolfe,

N. S. W. Department of Agriculture, Tamworth.

By world standards, the Australian climate is uniquely dry, Australian soils are uniquely infertile, and Australians are an independent lot. It follows that Australian pastures should be improved by species and methods that are consistent with our unique environment. We are not in Britain, or New Zealand, or the U.S.A.; hence, new pasture technology from overseas countries must be proven under Australian conditions before it is promoted to local farmers and graziers. This is one of the reasons why the level of activity in agricultural research in Australia must be maintained. One of the benefits of local research and development is that our technology is exportable to other countries in the form of such dollar earning commodities as pasture seeds and agricultural machinery.

Landmarks to date in Australian agriculture have been the development of suitable machinery for large scale crop and pasture production, the use of superphosphate and other fertilizers to improve soil fertility, a realisation of the value of pasture legumes for soil improvement and conservation, the development of ley farming systems in which the fallow period is replaced by pasture legumes, the advent of grain legumes, and the advent of new tillage practices that may benefit both the productivity and stability of our farming systems.

Throughout the farming and grazing areas of Australia, there is a vital need to upgrade pastures. The pasture revolution that began after the second world war, and which reached a peak in the 1960’s and 1970’s, has slowed considerably. There is apathy and despondency on the part of science, agribusiness and primary producers is getting on with the job of pasture improvement. These attitudes are the result of several factors including:

1. The cropping is King Ethos. Farmers are neglecting pastures and there is insufficient recognition of the link between good pastures and good farming. The current trend in farming systems is to shorten the pasture phase - all the more reason to ensure that top quality pastures are grown during the pasture phase. The improvements that have been made to agricultural machinery for cropping purposes have not been followed by similar developments towards the improvement of machinery for pasture establishment.

2. New pests of pastures have occurred, such as the lucerne aphids, and these are in addition to old ones such as red legged earth mite, which is as devastating as ever. Furthermore, there have emerged new diseases such as clover scorch and root rots.

3. We are now recognising new soil problems, such as the increasing acidity of formerly productive soils.

4. There is abundant evidence of poor management of existing pastures, especially during the critical phases of seed production.

5. We have been subjected to an unfortunate run of poor seasons, which has lowered the seed reserves of annual pasture species and contributed to the death of many perennial stands. The variability of the Australian climate is something that we must face up to and live with.

6. Many of the pasture species and varieties that we use perform favourably in favourable seasons, but their performance in unfavourable seasons leaves much to be desired.

I positively believe that much can be done to change this state of affairs, through a combination of the appropriate choice of pasture species and varieties and through good management. My task today is to discuss the choice of pasture species and varieties, predominantly for the wheat/sheep zone which is of interest to most of the participants at today's conference, followed by a shorter discussion concerning the high rainfall zone. My remarks are relevant not only to a post-drought situation, but also generally.


In the wheat/sheep zone, pastures are sown and grown for livestock production, for soil improvement and for soil conservation. The pasture species that have been successful include three legumes - subterranean clover, annual medics and lucerne. Only one grass, annual ryegrass, has had any impact in this zone; since it is a weed of crops, it has been systematically eradicated to the point that now, more than ever, we are dependent on a dense productive legume component for the job that we expect our ley pastures to do.

A recent survey undertaken by Carter in the South Australian wheat belt revealed the overall seriousness of the problem, in this case in annual medic pastures (Table 1). He sampled at random 35 sites on commercial farms in the Mallala district. Only on 20% of these, seven out of 35, could the pastures be judged as good in terms of the seed reserve present in autumn and the seedling density present in winter. These statistics, seed numbers and seeding density, are vital indicators of the productivity and persistence of annual legumes such as subterranean clover and medics.

TABLE 1 - Survey of Medic Pastures, South Australia






kg/ ha

Plants/ m

Very Poor












SOURCE : Garter 1982

For high seed production in spring, favourable soil moisture conditions are needed for 10 weeks, from the time the first flower appears to the time that the last seed is set. Varieties of annual legumes differ considerably in the timing of their reproductive development. Taking subterranean clover as an example, we now have a range of varieties which mature from early in spring until early in summer (Table 2). A very early variety like Nungarin matures by late September, when soil moisture conditions are usually favourable even in low rainfall zones in southern Australia. Later maturing varieties grow well into spring, but how much seed they set is governed by the reliability of late spring rainfall.

TABLE 2 - The maturity of a range of Subterranean Clover Cultivars





Perth, May Sowing

(+ 70 days)



Late September



Mid-Late October



Early-Mid November



Late November

TABLE 3 - The Residual hard seededness of some Subterranean Clover Cultivars - Proportion of Seed Remaining Hard (= impermeable) after 4 months of typical summer temperatures




5 5-65



Seaton Park






The fate of the seed produced is governed by hard seededness, which again varies considerably between varieties. Hard seededness aids persistence by ensuring that only some seed germinates after false breaks in summer and early autumn. Hard seeds are those which are impermeable to water; they will not germinate until the seed coat becomes soft (permeable to water). During summer, a proportion of the hard seeds break down (become soft) in response to repeated day! night temperature fluctuations which eventually cause the seed’s coat to split. Generally the earliest maturing subterranean clover varieties, such as Nungarin and Paliak, retain more hard seeds at the end of summer than later maturing varieties, such as Woogenellup and Tallarook (Table 3). Harder seeded varieties are therefore suitable for sowing in drier localities, whereas’ the later types are adapted to localities with a longer growing season. However, in the variable climate of New South Wales, experience has shown us that a hard seed level of at least around about 20% at the end of summer is desirable to ensure the long term persistence of clover varieties. Just why this is so is illustrated in Tables 4 and 5.

TABLE 4 - Subterranean Clover Seed produced at Binya and Kamarah and its fate (Seed Yields in kg per ha)


SOWN 1977

SOWN 1978











Seaton Park










At Binya and Kamarah, in the middle of the southern wheat belt, results are presented for two trials, one sown in a drought year (1977) and the other sown in a favourable season (1978). In both years, Nungarin set more seed than the other two varieties, a consequence of its early maturity. This variety also carried over a considerable reserve of hard seed to the following winter, which was available for germination in subsequent years. In contrast, Woogenellup failed to set a considerable quantity of seed, and a high proportion of this was lost through summer due to false breaks. Very little was carried over for germination in a subsequent year if seed set failed. Seaton Park was somewhere in-between, combining a mid season maturity with a reasonable level of hard seededness. In winter 1979, the number of seedlings that regenerated on the Nungarin and Seaton Park plots was considerably more than those on the Woogenellup plots.

TABLE 5 - Performance of Sub Clover Cultivars on the Central Slopes (Dunedoo)

























Second, I present some data obtained on the performance of subterranean clover cultivars on the central slopes, at a site 60 miles east of Dubbo (Table 5). Here, after a favourable season in 1979, drought conditions prevailed in 1980. The relatively hardseeded strain, Daliak, maintained its seed reserves throughout and regenerated well after the drought in 1980, whereas Woogenellup failed.

It is observations such as these that suggest that the level of hard seededness in mid season and late strains is insufficient for them to persist in the erratic climate that is evident in New South Wales. The relationship that we see between hard seededness and maturity in the current range of subterranean clover cultivars can be changed by appropriate breeding and selecting to produce a relationship that is more suited to New South Wales conditions (Figure 1).

FIGURE 1 - The Correlation Evident Between the Maturity and Residual Hard seededness of Subterranean Clover Cultivars.

You may be surprised to learn that recent evidence has come to hand that subterranean clover varieties do not differ very much in their winter growth, providing that they germinate at the same time and that their seedling density is similar. At Wagga in 1981, micro- swards of several strains were thinned to the same density and their growth was compared under a weekly defoliation regime; that is, they were evaluated under the same sorts of conditions that would occur in a paddock grazed by sheep. Up to the middle of August (day 119) the productivity of an early strain (Nungarin) and a mid season strain (Woogenellup) was similar (Table 6). Thereafter the productivity of Nungarin fell away due to the fact that it was beginning its reproductive development, producing seeds and putting down burrs. When the experiment ended in September (day 168) and the residue of uncut above ground material was added to the previous growth, the total production of the two strains was very similar.

TABLE 6 - Winter Productivity of Sub Clover Strains Defoliated Weekly, Wagga 1981






1.Growth Removed by Weekly Cutting


Day 0-119



Day 119-168



2.Residue of Clover Tops


Day 168



3.Total Production


Day 0-168



From this evidence, and from similar findings by R.C. Rossiter and W.J. Collins in Western Australia, I conclude that herbage yield of subterranean clover in winter is mainly a function of plant density, an a function of maturity. This reinforces my theme that persistence is productivity. Greater efforts to improve the per-plant productivity of subterranean clover in winter will not come to much in my opinion. However there are a number of other limiting factors that, if present, do seriously retard the growth and/or persistence of plant varieties and/or species. These include, as I have indicated before, factors such as the occurrence of diseases and pests, plant nutrient deficiencies and toxicities, waterlogging and other factors. For example, consider the effect of waterlogging on clover growth - a tolerant strain, Trikkala, grows well under waterlogged conditions, whereas an intolerant strain such as Seaton Park does not. It is the objective of plant breeding programmes to overcome these limitations to plant growth.

In Table 7, the available range of commercial subterranean clover varieties is shown, ranging from very early to late season varieties. Many of these varieties have become available only in recent years and notable among these is Nungarin which was released in 1977, Dalkeith, a hardseeded early strain which will be released in 1984, Trikkala which is proving its worth in some situations but which is insufficiently hardseeded to be a completely satisfactory alternative to Yarloop, and new harder seeded and disease resistant strains that will become available soon as alternatives to Woogenellup and Mt. Barker. We are fortunate in Australia in having a national subterranean clover improvement and co-operation with groups in other states such as New South Wales, Victoria and South Australia. Subterranean clover improvement is undertaken at a national level.

TABLE 7. Sub clover varieties

Very Early







(X Bred)












Seaton Park









DA 20.19.2



(X Bred)



Mt. Barker








In the case of annual medics, the main improvements will come from the development of resistance to spotted alfalfa aphid and blue green aphid, both of which have had substantial detrimental effects on medic production in New South Wales, Victoria and South Australia. At the same time, the maturity and hard seed levels of medic strains will be adjusted to make them adaptable to different environments. Currently, new varieties such as Sephi and Paraggio are being developed by a combined effort between a national programme in South Australia and agronomists in New South Wales. In this case located at Condobolin in central New South Wales and at Tamworth in northern New South Wales. Medic improvement appears to be lagging slightly behind subterranean clover improvement, and the commercial availability of these new varieties is eagerly awaited.

I turn now to the only useful perennial plant in the Australian wheat belt, the king of fodders, lucerne. Recent evidence from places such as Wagga, Temora and Canberra have demonstrated substantial improvements to animal production through having a component of lucerne present in pastures. Compared with the base pasture, subterranean clover or a mixture of subterranean clover and phalaris, the improvements due to a mixture of lucerne and sub clover (+ grass) have ranged from 10 to 20% for wool production up to 100% in certain years for beef production at both Canberra and at Wagga (Table 8).

TABLE 8. Animal production increases from lucerne in pasture mixtures


+ 10 to 20%


+ 20 to 40%


+ 10 to 100%

The advent of aphids into Australia in 1977/78 did Australian agriculture an indirect favour. It showed, from an examination of the overseas material imported to meet the threat, the advantages that were available in terms of greater productivity and better persistence. Greater productivity was evident in the much improved seedling vigour seen in some of the imported varieties and their extra capacity for growth in late autumn and early winter. Better persistence was evident in the tolerance of the new varieties to the aphids, both spotted alfalfa aphid and to a lesser extent blue green aphid. Many of the newer varieties imported from the United States provided a source of tolerance to diseases such as crown rot, root rots and leaf diseases. However, few of the imported varieties provided all of the desirable characteristics that we believe Australian varieties should possess. Australian plant breeders were quick to respond, and as a result there are a number of new varieties becoming available to farmers which should prove to be a substantial improvement on the former Hunter River variety. These include Siriver from CSIRO, Trifecta from Queensland, Nova and a new unreleased variety from the New South Wales programme at Yanco, together with improved overseas types such as Maxidor II, Pioneer 581, TJL 515, Granada and others.

I wish to emphasise again, that the main benefits of these new varieties will be through greater persistence, which is more of a problem in northern New South Wales and southern Queensland than in the southern parts of the continent (Figure 2). Substantial areas of the dryland-cropping belt can and should be sown to lucerne, and I think it is here that we will see benefits in being able to maintain an adequate density of lucerne in grazed pastures. Currently, these new lucernes are being evaluated in terms of the short and long term performance, and the results are being progressively made available to guide producers in their choice.

FIGURE 2 - An Idealised Representation of the Persistence of Hunter River Lucerne in southern Queensland and southern N.S.W. and the likely Persistence of new Disease - Resistant Varieties.

In addition to the three big legumes in the wheat belt, subterranean clover, annual medics and lucerne, other legumes may, in time become important in certain localised areas. Nominated among these is Serradella which appears to be well adapted to acid sandy soils, and other clovers such as woolly cluster and cup clovers may be developed for specific purposes.


In the high rainfall zone of New South Wales, which occurs throughout much of the Tablelands areas, the most important pasture legume is and will continue to be subterranean clover. This is particularly true of the southern and central tablelands, and the development of new strains may extend the clover belt up into the western areas of the northern tablelands and northern slopes. White clover has a specific role to play in the more favourable areas of the high rainfall zone, particularly where average annual rainfall exceeds about 700 mm per year.

In the tablelands regions, the perennial grasses (both native and improved) do have a real place. But some of the claims made concerning perennial grasses are in my opinion exaggerated, almost absurdly so. The presence of a perennial grass does not in the short term, confer any benefit on animal production. The productivity of a perennial grass clover pasture is not meaningfully different from an annual grass clover pasture. Any benefit from the theoretical extension of the growing season afforded by a perennial grass is minimal. There is abundant experimental evidence from centres such as Canberra, Armidale and Glenormiston in Victoria to support these contentions, and I back these statements up with the data obtained by Reed at Glenormiston (Table 9). In this experiment, plots were sown to a mixture of subterranean clover, white and strawberry clovers, and to the same mixture of clovers plus either perennial ryegrass, phalaris, currie cocksfoot, a combination of any two of these grasses, or a combination of the three. Animal production, in this case measured by the liveweight gain of lambs, was not improved by the presence of a perennial grass in the mixture. All pastures grew well and the lower growth weight of weaners on the pastures containing perennial grass was associated with the lower legume content of these pastures.

TABLE 9 - Effect of Grass Species on LWG of Lambs (grams per day), Glenormiston, 1965-68.


No Grass

Grass Present










Source: Reed (1970)

So what is the value of perennial grasses3 There are two main benefits. The first and foremost is the effect of a persistent grass, and I underline persistent, on pasture stability and soil conservation. If perennial grasses are not present, undesirable species such as thistles and other weeds will increase and the productivity of the total pasture mixture will decline eventually. The second reason for growing perennial grasses is their value in reducing to more manageable proportions nutritional disorders such as the problem of cattle bloat. This applies particularly in the New England region of New South Wales.

Consequently it is important that when perennial grasses are sown at considerable expense, they do persist. The record of many in this respect, is not good. Data obtained by Hutchinson at Armidale illustrates that phalaris persisted considerably better than either cocksfoot or perennial ryegrass, with fescue being somewhere in between (Table 10). I believe the ability of phalaris to persist through drought, and there are plenty of examples available at present, is the outstanding characteristic of this grass. Faced with a choice of a high yielding but less persistent grass versus a lower yielding but persistent one, I would choose, and I think landholders should choose, the latter.

Failures are costly. So some sections of the seed industry take a perverse pleasure in promoting the flash in the pan type of plant, since failure and reseeding is inevitable. Why do many research scientists continue the practice of assessing the value of pasture plants under ideal conditions, with fertilizer and water laid on, when our climate is far from ideal. Why do farmers always take most of their pointers from what happens in a good year, at which time they usually have insufficient stock to take advantage of the extra growth that occurs, when it is the bad year that make a mess of their bank accounts.

TABLE 10 - Species Persistence under Grazing (19 sheep per ha) during the 1965 drought at Armidale, measured as basal cover percent.


Spring 1964

Spring 1965













Source: Hutchinson (1970)

In the same vein, we too often underestimate the value of our native perennial grasses. Recent work undertaken in the northern tablelands has shown that a stable and a productive association can be maintained between native grasses and an introduced legume. The difficulty and expense of introducing an improved perennial grass is often not justified, and it is worthwhile to continue our efforts to maintain the balance between the native grasses and the legumes. The native grasses provide stability, the legumes provide production. The performance of native grasses through the recent drought is a testimony to their ability to survive in the Australian climate.

The main benefits to be had from pasture improvement is to improve the content of our legumes in tableland pastures. The current situation is not good. A survey conducted recently by Brian Dear and Peter Simpson of the N.S.W. Department of Agriculture showed just how poorly subterranean clover fared through the drought of 1982 on the southern tablelands (Table 11). Seed reserves on most paddocks declined below 150 kgs per hectare, a desirable minimum. It is noteworthy that in those cases where seed reserves were above this figure, the strains concerned were harder seeded strains such as Seaton Park and Daliak rather than the softer seeded strains such as Woogenellup and Mt. Barker. In fact, Woogenellup and Mt. Barker have been caught out on a number of occasions in the last few years. As I mentioned before, higher levels of hard seededness are required in our later maturing varieties. Until this happens I advocate the sowing of mixtures of subterranean clover strains, combining an earlier harder seeded strain with a later maturing, softer type. Examples include the combination of Nungarin and Seaton Park on the slopes and Daliak and Woogenellup on the Tablelands.

TABLE 11. Sub clover survey, southern tablelands summer 1982/83

Number of Sites

Seed Yield




< 50







Source: P. Simpson, B.S. Dear

It is some years since we have seen a season in which late clover is abundant on the Tablelands. Many graziers would not mind a bit of bloat in return for the improved productivity and persistence of white clover. At the moment I believe the westward limit to white clover is about 700 mm or 28 inches average annual rainfall, but newer strains such as Haifa are improving the persistence of white clover quite measurably above the Victorian and New Zealand varieties.

In future, there will be some effort put into evaluating other species of legumes such as Persian clover, Sainfoin and Caucasian clover in Tableland environments. There is not much work going on at present to improve perennial grasses for use on the Tablelands. Perhaps the greatest benefits shall come from the efforts to further improve Phalaris. As I have said before, I do not place much hope on the importation of a new grass from overseas to overcome our problems. I am never particularly impressed that grass ‘A’ grows better than grass ‘B’ in winter, since inevitably grass ‘A’ suppresses more of the growth of the other species associated with it in the pasture mixture, and the total pasture productivity is hardly altered.


To sum up my philosophy concerning improved pasture plants it is that persistence equals productivity and stability. Markers that are important in helping you determine the success or otherwise of the choice of species you have made, or your management of them, will include the seed reserve of subterranean clover that is present which we measure regularly in our experiments.

As producers, you must recognise the factors that are limiting the long term productivity of your pastures, the main one of which is rainfall. However as I have mentioned there are others and where a particular plant species offers an advantage it may well be worth trying. All emphasis in pasture improvement should be on improving the legume content and subterranean clover will, be particularly important through improved pasture areas of New South Wales. Lucerne and annual medics have specific value in several situations.

The choice of varieties is crucial. Always select persistent varieties from the recommended list. Discuss with your neighbours what has survived the drought, follow their example. If sowing a grass, persistence is vital because of the expense of sowing and managing the improved grass - I recommend phalaris wherever possible.

Establishment technique and management are vital, and these will be the subject of subsequent talks.


1. Carter, E.D. (1982) - The need for change in making the best use of medics in cereal - livestock farming systems of South Australia. Proceedings of the Second Australian Agronomy Conference, Wagga 1982. p. 180

2. Carter, E.D., Wolfe, E.C., and Francis, G.M. (1982) - Problems in maintaining pastures in the cereal - livestock areas of southern Australia. Proceedings of the Second Australian Agronomy Conference, Wagga 1982. pp. 68-82.

3. Collins, W.J., Rossiter, R.C., and Wolfe, E.G. (1983) - The winter production of some strains of subterranean clover grown in defoliated swards. Australian Journal of Experimental Agriculture and Animal Husbandry 23 (in press).

4. Fitzgerald, R.D., Simmons, K.V., and Southwood, D.R. (1980) - Lucerne. Department of Agriculture New South Wales, Division of Recent Industry Bulletin. p. 2.5.7.

5. Hutchinson, K.J., (1970) - The persistence of perennial species under intensive grazing in a cool temperature environment. Proceedings of the Eleventh International Grassland Congress, Surfers Paradise. pp. 611-614.

6. Reed, K.F.M. (1970) - Variation in liveweight gain with grass species in grass-clover pastures. Proceedings of the Eleventh International Grassland Congress, Surfers Paradise. pp. 877-880.

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