Short-rotation Ryegrass in southland

New Zealand Journal of Agriculture, Volume 79, Issue 3, 15 September 1949, Page 279

Short-rotation Ryegrass in southland

SHORT-ROTATION ryegrass is not grown extensively in Southland, though it has characteristics which may prove valuable under Southland conditions. Indeed, if it were grown more widely, shortrotation ryegrass would solve some of the problems which confront the Southland farmer in connection with seasonal grass production. There are other reasons why farmers would be well advised to establish short-rotation ryegrass, the characteristics and value of which are dis-

cussed in this article by

A. R. Rankin,

Fields Instructor, Department

of Agriculture, Invercargill.

AFTER sowing, short-rotation ryegrass establishes very quickly and is . thus an excellent deterrent to weed growth. Competition from weeds is a very definite danger to any pasture in its early life, but short-rotation ryegrass, because of its quick establishment, is better able to overcome weeds than most other grasses. However, this does not mean that cultivation before sowing can be neglected and that reliance can be placed on short-rotation ryegrass to overcome the weeds; cultivation should be just as thorough as for the sowing of an ordinary pasture.

Unfortunately, clovers can be affected in exactly the same way as weeds and unless care is taken shortrotation ryegrass will also choke out clovers. Grazing with large numbers of sheep for a short period about 6 weeks after sowing will enable the clovers to establish and compete more successfully with the short-rotation ryegrass.

Establishment and Palatability

The rapid establishment of shortrotation ryegrass was shown in a paddock of 12 acres at Otapiri which was sown on December 29, 1944. Two months after sowing carrying capacity was 8 hoggets to the acre and a fortnight later 13 hoggets per acre. The paddock, which provided ample feed all the time, is an excellent example of how well the grass establishes in a short period.

Short-rotation ryegrass is greatly favoured by stock and is much more palatable than perennial ryegrass. It has been found that a proportion of short-rotation ryegrass included with perennial ryegrass in a mixture will raise the palatability of the pasture considerably.

As is only natural, persistency will depend on the . conditions under which the grass is grown and the treatment it receives after sowing. Under suitable conditions of fertility and moisture and given proper management it is possible for short-rotation ryegrass to be virtually permanent. .

The breeding of short-rotation ryegrass began in 1937 and since then breeding and selection have been directed toward improving the persistency of the grass, yet retaining its other characteristics.

The improvement in persistency was demonstrated in a trial conducted by the Grasslands Division of the Department of Scientific and Industrial Research at Palmerston North in which the’original selection of short-rotation ryegrass (which was not released into

commerce) was compared with the latest selection available. The pedigree strains of Italian ryegrass and perennial ryegrass together with a poor strain of perennial ryegrass were all planted out in rows as single-spaced plants. The experiment was laid down on July 4, 1946, and the trial area was subsequently grazed periodically with sheep. Survival counts were made on April 29, 1948, and the following figures show the percentage of plants still surviving in each line of ryegrass. Per cent. Poor perennial ryegrass .. .. 9 Pedigree strain Italian ryegrass . .19 Original selection of short-rotation ryegrass .. .. .. .. .. 30 Latest selection of short-rotation ryegrass .. .. .. .... 75 Pedigree strain perennial ryegrass .. 91 The figures give an excellent comparison between short-rotation and the other ryegrasses; the latest selection of short-rotation ryegrass compares very favourably with them all. Moreover, the marked improvement in the persistency of short-rotation ryegrass is also shown clearly. The most valuable feature of shortrotation ryegrass as far as the Southland farmer is concerned is its high out-of-season production. It will produce a good bulk of feed in winter and early spring when other grasses are dormant and for this, reason alone greater use of short-rotation ryegrass in Southland can be recommended. An indication of the high winter production of short-rotation ryegrass is shown by the following figures, which give a record of the stock carried on a 12-acre paddock at Otapiri.

Period Stock carried June 6-July 24 20 rams July 25-Aug. I 200 ewes and 20 rams Aug. 2-Aug. 16 500 ewes (2 to 3 hours daily) Aug. 17-Aug. 30 500 ewes (continuous grazing) Aug. 31-Sept. 15 Spelled Sept. 16-Sept. 20 140 ewes Sept. 21-Sept. 22 80 ewes Sept. 23-Oct. 9 100 ewes The carrying capacity for June, July, and August must be classed as remarkableit illustrates the potentiality of short-rotation ryegrass for high out-of-season production, the value of which cannot be over-stressed. One of the greatest difficulties confronting the Southland farmer is the provision of grass feed during the winter and early spring months. September and October, in particular, are critical months and at this period feed is very shortswedes are past their best and kale and chou moellier, even if sown late, have reached the flowering stage. Short-rotation ryegrass will definitely assist in overcoming this shortage of feed.

Moreover, the fact that the Southland farmer is forced to put his faith completely in supplementary feed for such a long period undoubiedy leads to stock troubles. A recognised method of reducing such troubles is by providing greenfeed and here again short-rotation ryegrass would prove invaluable.

For many years both perennial ryegrass and Italian ryegrass have been used extensively in New Zealand pastures. . On high- and medium-fertility country perennial ryegrass is the main component of permanent pasture mixtures, while Italian ryegrass holds a similar position in temporary mixtures. These two ryegrass species, though closely related botanically, differ widely in their characteristics. True perennial ryegrass, for instance, is a long-lived species, while Italian ryegrass is classed as an annual. Italian ryegrass establishes more rapidly than perennial ryegrass, produces a greater bulk of feed in winter and early spring, and is more palatable to stock.

It was felt that a ryegrass species combining as far as possible the best features of both perennial ryegrass and Italian ryegrass would fill a definite place in New Zealand grassland farming, particularly in districts where a system of short-rotation grassland farming was practised.

In 1937 a start was made to raise such a species by the hybridisation of perennial and Italian ryegrass, which are completely inter-fertile and cross readily in the field. The initial resulting hybrids vary greatly in their characteristics, which means that . a great deal of selection work is necessary in order to isolate the type of plant desired.

Plants showing the best combination of the desirable features of Italian ryegrass and of perennial ryegrass were selected from these hybrids. From these plants were selected those which were best able to pass on the desirable characteristics to their progeny, thus ensuring that the type finally selected would be retained through several generations of multiplication. As the work of breeding has progressed, so a general improvement in the type of short-rotation ryegrass plant has been achieved.

Suitable Country for Short-rotation Ryegrass Short-rotation ryegrass demands high fertility and will do well on good ryegrass-white clover country; it does not like wet, waterlogged soils or lowfertility country which will support only browntop, sweet vernal, Yorkshire fog, and other low-fertility-de-manding species. Availability of nitrogen is also an important factor, as short-rotation ryegrass is a heavy nitrogen demander and on soils deficient in nitrogen it will have a very unthrifty appearance. Even where nitrogen is plentiful at the time of sowing and is not replaced it will be depleted quickly because of the rapid establishment and high initial production of the short-rotation ryegrass. Thus on country suitable for the growing of short-rotation ryegrass it is not uncommon to see the same yellow, unthrifty appearance in the early life of the pasture as is produced when the grass is grown on the unsuitable nitro-gen-deficient soils.

On a short-rotation ryegrass paddock at Winton which was showing signs of nitrogen deficiency as a result of the demands made by the ryegrass 2 plots were topdressed with lewt. of sulphate of ammonia per acre and within a fortnight the ryegrass had shown a definite improvement.

Pasture Mixtures

To the Southland farmer short-rota-tion ryegrass is valuable mainly for the grazing it provides. Seed production. and haymaking tend to weaken pastures, and for Southland conditions short-rotation ryegrass offers more advantages when sown for grazing. It can be used for grazing in two ways: As a straight-out, special-purpose pasture, or as a component of a permanent pasture mixture.

The addition of a few pounds of short-rotation ryegrass seed to a mixture will have a very beneficial effect on the palatability and production of a pasture in the first year or two. Beside this, its competition with weed growth will be valuable, and though the short-rotation ryegrass may die out after 2 years, the benefits obtained definitely warrant its inclusion.

On good white clover country the following seed mixture is suitable: —• lb. per acre Certified short-rotation ryegrass 15 Certified perennial ryegrass .. 20 Certified white clover .. .. 2 Certified Montgomery red clover 2 This mixture can be modified to suit particular requirements and areas where the soil fertility is not as high as on good white clover country and the total quantity of ryegrass can be reduced and species such as cocksfoot and crested dogstail included.

In Southland the fullest benefit is obtained from short-rotation ryegrass where it is used for special-purpose pasture. However, it would be unwise to sow this type of pasture on any but highfertility country. Clovers are . of great importance in a short-rotation ryegrass pasture, as it is by means of clovers that the ryegrass obtains its nitrogen. On highfertility areas which are depleted of nitrogen in the early stages, due to the rapid growth and high initial production of short-rotation ryegrass, the nitrogen balance can be restored if clover content and establishment are good.

A seed mixture suitable for sowing as a special-purpose pasture is as follows: — lb. per acre Certified short-rotation ryegrass 30 Certified white clover . . .. 1 Certified Montgomery red clover 2 Certified cowgrass 2 Establishment The seed-bed . should be well compacted from the bottom to near the surface, with a shallow tilth at the surface to enable the seed to be properly covered. Unless conditions are unusually favourable, seed will not germinate in a seed-bed .that is .at all cloddy; particularly is this the case with clover seed, which has a hard protective coat through which moisture will not readily penetrate. A cloddy seed-bed leaves open spaces below the surface, which prevent moisture from rising to the seed and germinating it. It is for this reason that it is not unusual to see a good strike of grass and a poor strike of clover. The need for strong clover growth has already been stressed, but this cannot be obtained unless the condition of the seed-bed allows good clover establishment.

All deep working should be completed in time to allow for a fallow of 6 to 8 weeks before sowing. During this fallow the area should be given only light cultivation which is sufficient to reduce loss of moisture and eradicate weed seedlings; the soil is also compacted from the bottom upward and weathering and aeration assisted, with a consequent increase in soil fertility. The final firming of the seed-bed is achieved by further use of the harrows and one or two rollings. A firm rolled surface is best for sowing seed on and sowing should be followed by a light stroke with .the harrows. The pasture can be sown in November, December, January, or February,

but if sowings are too late, clover establishment may be adversely affected. One ton of lime per acre should be applied before sowing and 1 to 2cwt. of superphosphate sown with the seed.

Maintenance

An annual topdressing of 2cwt. of superphosphate and scwt. of lime per acre will maintain a vigorous growth of clover, which in turn will maintain the short-rotation ryegrass. Grazing management also plays an important part and incorrect grazing will reduce greatly the life of the pasture. Six to 8 weeks after sowing, the pasture should be grazed to encourage tillering and to prevent clovers from being smothered. It is best to graze with a concentration of 20 to 30 sheep per acre for 3 to 4 oyer-grazing before young plants are well rooted is harmful and poaching must also be avoided. Care must be taken also with subsequent grazing, as short-rotation ryegrass does best when it is leniently and rotationally grazed.

In a trial conducted at Palmerston North by the Grasslands Division of the Department of Scientific and Industrial Research a comparison was made on the effect of grazing on perennial ryegrass and short-rotation ryegrass. Three paddocks were sown with a complete mixture, including 151 b. of short-rotation ryegrass and 201 b. of perennial ryegrass. Each of these paddocks received different grazing treatments. The first wak . grazed continuously, the second rotationally, and the third was grazed rotationally with long spells between grazing. Eight months later turves were removed from each paddock. These were analysed and the percentage of each pasture species present was calculated, the results being as follows: —

Rotational grazing Continuous Rotational with Species grazing grazing long spells (per cent.) (per cent.) (per cent.) Short-rotation ryegrass ..3 21 40 Perennial ryegrass .. 43 40 30 Other grasses 8 12 trace White clover ..42 24 23 Red clover .. 3 2 5 Other species I 12

From these figures it can be seen that under hard grazing short-rotation ryegrass was virtually eliminated. However, where grazing management suited the short-rotation ryegrass it was very much in evidence. It must be remembered that the trial was not conducted under Southland conditions; however, it gives a general idea of the effect of grazing management on short-rotation ryegrass.

The main production from shortrotation ryegrass is in late autumn, spring, and early summer, but in late summer and autumn production is low. At this period, however, clovers, particularly red clover, are growing vigorously. The pasture mixtures recommended earlier are excellent combinations for maintaining growth throughout spring, summer, and autumn. It must be recognised that the pasture is not permanent, but is designed to give high out-of-season production for about 3 years or longer. ■