VALUE OF STRAINS OF RYE-GRASS IN CANTERBURY.

New Zealand Journal of Agriculture, Volume 53, Issue 3, 21 September 1936, Page 146

VALUE OF STRAINS OF RYE-GRASS IN CANTERBURY.

J. W. Calder,

Canterbury Agricultural College, Lincoln.

Canterbury is recognized as one of the main cropping-areas in the Dominion, and the climate and soil conditions are particularly suited for this type of farming. Nevertheless, the greater part of the land is in pasture. Of the 2,750,000 acres of cultivated land, 1,750,000 acres are in grass over two years old, and about 250,000 acres are sown down in new grass each year. Cereals and pulse crops occupy about 500,000 acres and fodder crops about 250,000 acres. The 750,000 acres of crops are sown in rotation with pastures which remain down from two to ten years 01; so, and the young grass is sown at the end of a cropping programme. Owing to climatic conditions, these pastures fail to provide the necessary feed at two —namely, in winter and early spring as a result of low temperatures, and in summer and early autumn as a result of drought. It is necessary, then, to provide the supplementary feeds for these two periods. Turnips, hay, chaff, green-feed oats, and Italian rye-grass for the winter and early spring, and green-feed rape, soft turnips, &c., for summer and autumn periods. These supplementary feeds are essential, but they are costly to grow, so that any feed which can be secured from pastures at these times will

lower the cost of producing supplementary feeds, and will be more valuable than a heavier production during the periods when feed is plentiful. Variations in the type of farming in Canterbury on the different •classes of land and on different farms on the same class of land are frequent. One farmer might run a grazing-farm, another a croppingfarm, but the majority are engaged in mixed farming and can increase or reduce the grassing or cropping as the market conditions indicate. This is shown by the correlation between the number of sheep and the area in grass. For example, let us compare the two seasons 1932-33 and 1933-34. In the latter season there were 450,000 more sheep in Canterbury than in the former season. This increase was associated with an increase in grass area as follows : Old pasture, 56,000 acres ; new grass, 49,000 acres, while 28,000 acres less seed (grass and clover) and 15,000 acres less hay were cut. In addition to the extra feed from pastures, there was an additional 14,000 acres of fodder crops. Cropping was reduced by 50,000 acres. This means that many of our pastures in the cropping district must be capable of remaining for several years in a productive condition when profits from lamb and wool are greater than the profits from cereal-growing i.e., the dominant species shown in a mixture should be permanent ones. When a period of profitable ■cereal-cropping arrives the farmer will then be in the position of having to make a decision as to which of his pastures he will plough up rather than in the position of having to plough up a field because there is no grass on it. And it needs little imagination to visualize the better crops which will be obtained when a good turf which has been well stocked be ploughed under than when a bare open caked surface be turned over. One is well aware that other factors, such as management, manuring, and climatic conditions, will all have their effect in making a good pasture, but, unless the foundation of perennial plants is there, a satisfactory long-lived pasture cannot be secured. Perennial rye-grass can occupy the dominant position in most permanent pastures on the medium and better soils where it persists and its production is influenced by rainfall and management. It shoots to seed readily on the approach of dry weather and remains in a dormant state until conditions again favour growth. On the light plains it does not satisfy the requirements of a permanent pasture after the relative high fertility associated with fodder crops and cultivation has reached normal in two or three years. The rapidity with which these soils dry ■out and their low moisture-holding capacity make conditions too severe for permanent productive rye-grass pastures. For long term pastures on this class of land cocksfoot should form the dominant constituent in the mixture. Strains in New Zealand Rye-grasses. Some years ago it was the general experience that perennial rye-grass would not hold for more than a year or two on many areas in Canterbury. Dr. Hilgendorf, when he commenced work on grasses, drew attention to the fact that, in Canterbury, it was not so much perennial rye-grass that was at fault, but the strain of ryegrass used. He grew plots of the ordinary commercial rye-grass alongside plots of rye-grass harvested from a field which had been in grass from forty-five to fifty years, and at the end of two years about

go per cent, of the plants from commercial seed and 5 per cent, or 6 per cent, of the plants from the old pasture had died. Mr. Levy,-at Palmerston North, grew a comprehensive series of commercial lines of rye-grass from throughout New Zealand, and he showed that the only lines of true perennial which were being harvested and sold on the market came from old pastures in non-cropping areas, chiefly from Hawke’s Bay, with the result that these lines now occupy the predominating position in the Department’s certification scheme, which was started as the result of these trials. Origin of Strains. What is the origin of these temporary strains ? Among the crops that are frequently, grown in Canterbury is Italian rye-grass. Sown in summer or early autumn, it provides valuable autumn, winter, and spring green-feed for ewes and lambs when pastures are dormant. After the flush of other feed arrives it is shut up for seed. From 10,000 acres to 15,000 acres of Italian rye-grass are so used each year. This, in itself, would probably not have been detrimental to the perennial strain of rye-grass, but, in addition to its use as a fodder crop, a small amount of Italian was often included in the rotation pasture-mixture with the object of providing the valuable winter and early-spring grazing. These pasture-mixtures were predominantly perennial rye-grass, and, when conditions warranted, they were shut up for seed. The seed crop, especially in the first year, would contain a percentage of Italian ryegrass in it. If this mixture were only a mechanical one, and was purchased with this knowledge, no harm would result, but experimental work has shown that the two species, Italian and perennial rye-grass, are readily cross-pollinated, with the result that, in addition to a mechanical mixture, we get a biological mixture. Frequently this complex mixture was sold as perennial, and was included in a pasturemixture together with a bit more Italian, and so the process went on for some generations, until many of the lines were predominantly Italian or Italian hybrids. They were temporary in nature, and contained a small percentage of perennial plants according to the number of generations that they were exposed to Italian contamination.

The Value of Strain in Rye-grass.

In the first place, true perennial rye-grass is long-lived under a wide range of soil and management conditions, and should form the basis of mixtures for the rotation pastures of from two to ten years or so on medium to better class soils. The temporary strain thins out after the first year or two, and low-production grasses, such as brown-top, sweet vernal, fog, or Danthonia, establish on the bare spaces and soon gain possession. The widespread occurrence of these and other pasture weeds on many areas of cultivated land is mute testimony of the temporary nature of the sown species. The temporary strains, owing to their Italian “ blood,” produce earlier and more palatable grazing, and this superiority may last for a few months, but, after the first autumn, a high percentage of the plants die, so the strain is not at all suited for the long-term pastures. For one or two years’ grazing on all soil types supplying the autumn, winter, and spring periods the Italian and red-clover mixture is supreme. The occupation of the sward by the-

true perennial rye-grass under good management gives a higher carryingcapacity than a sward dominated by the low-producing but long-lived .brown-top and Danthonia, and this in turn means higher fertility when the pasture is broken up for a period of cropping. The treatment which perennial rye-grass gets is responsible for its behaviour, and many pastures are ruined by overgrazing at critical periods. This applies particularly to the pastures of the light, shingly plains. During dry periods the perennial rye-grass dries up or shoots to seed, and unless there are supplementary feeds available the pastures are of necessity heavily punished by ' overgrazing. This period of overgrazing during drought weakens the plants, and those that do not die are unable to grow vigorously when conditions do favour growth. Palatability. The question of palatability has been prominent in reference to the perennial rye-grass. There is no question that it is less palatable than Italian or than the “ mixture ” with which it has .so often been compared to its disadvantage. When badly managed, the unpalatable nature can be so emphasized that sheep will not •eat . it, and go back in condition. Under good management, however, it forms the basis of a palatable pasture on which sheep thrive. Most of the criticism against perennial rye-grass has fallen ■on those pastures which were sown with pure rye-grass for seed purposes, those which had become rank before grazing, or those which had been cut for seed, the dry aftermath being grazed. Another condition which accentuated the unpalatable nature was the practice in cropping-farms of sowing the grass in the autumn after one or two cereal crops. Under these conditions the fertility is relatively low, the soil is dry and the tilth is poor, with the result that autumn growth of grass is slow and the plants are fibrous and lack vigour. This pasture will remain poor and unpalatable for two or three years, while one sown on a fertile .and well-prepared seed-bed will be of high production right from the start. Palatability is important, for, after all, the feed is grown for the stock, and they eat less of an unpalatable food and consequently do not thrive. Therefore, every effort should be made to keep the grass as palatable as possible by sowing suitable mixtures, by grazing it when reasonably short, and by sowing under highfertility conditions.

Competition in a Mixture

There is another factor which must be taken into consideration, and that is the effect of competition of perennial rye-grass on its associate plants in the mixture. Perennial rye-grass is an aggressive plant not only in the first year, when it is severe, but also in succeeding years to a less extent. This aggression is the result •of its relative rapid growth on a cultivated seed-bed, its strong growth under stocking, and the thickness of seeding which is usually applied. It thus competes with other plants in the mixturecocksfoot, red clover, and white clover— are slower to establish. The effects of this competition are not so marked when the mixture has been sown in November, December, or January, because the more slowly established plants, though checked, are

not killed, and, after some autumn grazing and dry weather has checked the rye-grass, they are enabled to become sufficiently well ' established to survive the winter, and later contribute to the feedsupply. When, however, the mixture is sown in late February, March, or April, as is commonly done in cropping-areas, the checking of the cocksfoot and clovers is responsible for their slow development, and the clovers are hardly out of the three-leaf stage and the cocksfoots are only small plants when the frosts come. In this stage they are subject to frost-lift, more especially when the ground is wet. In order to make conditions as favourable as possible for the other plants sown in the mixture with perennial rye-grass, early sowing should be practised and the young pastures should be judiciously grazed to prevent a smothering growth of rye-grass. Conclusion. The true perennial rye-grass strain is a long-lived perennial, and should form, the basis of all long-term pasture-mixtures on all but the lightest and driest soil types, while the temporary type, which is not perennial rye-grass at all but a hybrid mixture, is shortlived, and should be omitted from all long-term pastures. There is a difference in palatability between the two, but the lower palatability of the true perennial can be minimized by sowing well-proportioned mixtures, by encouraging rapid growth, and by keeping the grass grazed to prevent its becoming tough or fibrous. The severe ' competition exerted by perennial rye-grass is responsible for a deficiency of associate plants in a pasture, but this can be minimized by early sowing and by grazing to prevent the rye-grass developing a smothering growth.