THE GRASSLANDS OF NEW ZEALAND.*

New Zealand Journal of Agriculture, Volume XXIII, Issue 5, 21 November 1921, Page 257

THE GRASSLANDS OF NEW ZEALAND.*

PRINCIPLES OF PASTURE ESTABLISHMENT.

E. BRUCE LEVY,

Biological Laboratory, Wellington

TV T EW Zealand is essentially a land of pastures, and the endeavour X of its farmers is to grass every type of country from the seashore to the line of perpetual snow. In no other country is

the farmer more dependent— rather, more able to depend — pastures for the sustenance of his stock than in New Zealand. The study of pastures is therefore, with us, of national importance, and their improvement of national gain.

Each type of pasture decidedly has a life-history—a life-history subject to modification under the many vicissitudes of soil, climate, and environment,' made complex or simplified according to the species concerned in the pasture association, and by the method of utilization of the feed produced. Given constant conditions, we get a definite life-history. For instance, in a pure cocksfoot association unstocked and harvested each year for seed we get, for an indefinite

* During the past ten years the writer has carried out a great deal of work on the grasslands of New Zealand as a whole, and this article begins a series planned to place before farmers the results of those investigations. In the course of these studies he has endeavoured to so record the results that they may be presented in an attractive and simple form, and in this the camera has been made use of to a very large extent. He has been greatly assisted also by the advice and guidance of Mr. A. H. Cockayne, Biologist to the Department.

period of years, a pure association, but just so soon as the important factor of stocking is brought to bear the life-history of that association becomes modified (Fig. r). Our country, ecologically speaking, is one of. uneven . climate, and of varying soil-surfaces and topographical features. It is also one of varying farm practice and management. The larger the area we investigate at any one time the more fully is this statement borne out, and the smaller the area we investigate the more constant will be the influencing factors and hence the less applicable will such statement be. In - dealing with pastures in a wide sense, therefore, very little information as to the treatment of any one special type of soil can be given ; yet when we study the whole problem we find, as one would naturally expect, that there are certain basic principles underlying the establishment and maintenance of our grasslands , in. general. It is my intention to outline these basic principles, .and later to show how they may be correlated with those special conditions existing in any one particular district or locality. In other words, an endeavour will first be made to get a good general knowledge of the factors governing pasture establishment and maintenance, and then to consider in detail the application of these principles to special types of soil. . Many farmers know, and know only too well, that of the species of grasses and clovers they include in their mixtures only a few may be represented in the pasture a few years after sowing. The species they have sown have disappeared, and other plants, generally weeds that they did not sow, have come in (Fig. 2). Changes have taken place, and the question may well be asked, What are the factors which influence these changes, and what consideration should we give that these weed successions may be avoided ? I claim that the weed succession can be to a large extent prevented, but that changes of species in the grass cover on most soils cannot economically be avoided. The permanent sward must be reached by a series of gradual changes in the pasture, and the fact that these changes will and do take place must be recognized and faced by the, farmer. In almost every type of soil there will be a changing or transitional period, and the recognition of this period by the farmer and a guiding of the transition through that period is one of the fundamentals of permanent establishment. Transitions in our grasslands will be dealt with in the next article of this series, and their significance will then be clearer. Among all the types of country which the farmer has to grass the transitional period is least marked on good average first-class country (Fig. 3), and of the types to be considered this one affords a convenient starting-place. , ■

I. GOOD AVERAGE FIRST-CLASS LAND

The successful grassing of this type of land really affords fewer problems than that of any other. A complete.sward of grass on such land is very easy to secure, but we must bear in mind that because the surface is completely clothed with grass and other vegetation it does not necessarily follow that that cover of vegetation is the best possible one that the farmer could attain on that particular soil. Fertile soils in temperate climates will support almost any plant, the. fact of high fertility meeting in most cases the demands even of the most ravenous

of ; those species which. are included in the sowing. Again, the capillary attraction in such soils is better than in the coarser, more gravelly soils, and consequently their moisture content is higher and more uniform. This factor of a more uniform soil-moisture is of very great importance to the longevity of certain of our pasture - plants, whose growth and very existence depend on conditions being such that free root-formation may take place at the surface of the soil, which is not possible unless moist and shady ’ conditions prevail at the soil-surface. With grasses in general it must be recognized as a fact that the root-system is not a permanent accessory to the plant. Each year a fresh root-system is developed • (Fig. 4), and with the exception of those plants of a creeping underground-stem nature, or short-tillering rootstock, the new root-system has its origin from a node of the creeping stem of the grass or from the base of the stem immediately above the soil-surface. We can therefore easily understand that if such portions of the plant are exposed to drying winds owing to bare patches or thin sole of grass, or through , too close grazing, a fresh root-system cannot develop and a stunted grass-growth results. .

In establishing a permanent pasture on good average first-class land it is expected that some at least of all species sown will survive (excluding the purely temporary elements as represented by Italian ryegrass), and will form part and portion of the herbage of the pasture throughout its life-history. This is not the case with any other type of pasture. In all other types, as before mentioned, one has to recognize the transition period in which changes. take place in the pasture association, 'owing to certain of the constituents, which for economic reasons must be included in the sowing, running out and being displaced by other species more suited to occupy that particular soil. In good land, however, where the demands of each plant are catered for, each is able to persist, and when establishing a pasture on such land it is really a question of a selection of those plants which will combine well and produce the maximum amount of feed spread over the maximum period through the year.

Any farmer can produce a sole of grass on good country, yet to make that soil produce the maximum it is capable of demands as much skill as do the poorer types of country. The farmer is apt, however, to “ rest on his oars,” as it were, once the ground is completely covered with grass of almost any description, and very often in the course of investigation one has cause to be disappointed with the pastures produced on really good country.

THE MIXED PASTURE.

On many types of soil we must rely for, permanent pasture on more or less pure associations—danthonia, for instance, on much steep, unploughable country. But where there can be produced mixed pasture, then such should be one’s aim. Mixed pastures are preferable because (1) their growth-period is more uniform throughout the year than is that of pure pastures ; (2) they offer a variation of feed for stock and (3) the plant companionship is often mutually beneficial to the individual of the association. A short consideration of these points will make their importance clearer.

(1.) Uniformity of growth-period ; The ideal pasture is one that will produce the maximum amount of feed spread evenly over the’ whole period of the year. To secure such a pasture, we know, is an impossibility. If it were possible grass-farming would be easy. There would be no need of any fodder crops, hay, &c., because feed produced from grassland is the cheapest food, and the cheaply produced food, is always the most economical to use. Unfortunately, the seasonal yield from our grasslands is not uniform, and more expensive feeds must be produced in order that in the. flush of the season there will not be too much waste of grass through carrying insufficient stock. Just so near, however,' as we approach the ideal pasture in farming, just so much credit is reflected on our management. The mixed pasture will approach nearest to this ideal.

(2.) Change of diet The appetite of live-stock is akin to our own, and one does not need to emphasize the fact that the human being sickens of a monotony of diet. The system demands a change, even although it may mean the consumption of certain foods generally accepted as unpalatable.' Palatability, therefore, must be looked upon as a variable thing, and the palatability of a food will depend very largely on its relative mass in comparison to the other foods. Turning to our pastures it is found, for example, that where we have a mixed pasture of English grasses, and where there are patches of paspalum in that pasture, such patches will be eaten absolutely close, while the mass of feed may grow rank (Fig. 5). If, on the other hand, there is a patch of those same English grasses in a paspalum field they will be grazed bare and the paspalum neglected. Thus are we likely to get a wrong conception of palatability. Certainly in a mixed association certain species are preferred by stock to others (Fig. 6), and once a species in a pasture is left uneaten it is a sure indication that that species is in excess. But it does not necessarily say that such species should be eliminated from the pasture altogether. One plant of tall fescue in twenty acres of a good mixed pasture may constitute an excess ; a thousand plants of tall fescue in one acre of paspalum may not constitute an excess. The balancing of the pasture ration is very important. The stimulation of the appetite of stock does not receive sufficient attention. The human knows that a little salt or a little herb in one’s food makes it more palatable, and more of that food is eaten. Stock are essentially machines for the elaboration of raw materials into concentrated products, and if they can be induced to take in more food by presenting it to them in an attractive form, then they will do more work for us —that is, if there is an excess of feedstuffs for them to work on. The mixed pasture from the variety-of-food viewpoint is certainly important.

(3.) Value of plant companionship : Particularly is this point true of the clover content of the pasture. The clover content of our pastures should be looked upon as being one of the most vital factors in the life-history of any pasture association. If we can keep the clovers going, the grasses will look after themselves. The companionship of clovers and grass is most marked. If clover be excluded from grass association on any but the fertile soils a more or less dried-up, stunted growth results, lacking that healthy green colour which 'reflects full nutrition and a tender palatable herbage (Fig, 7). Grasses respond rapidly to nitrogenous manures, as shown by the effect of the droppings of stock in promoting the patchy, uneven growth of pastures where

such droppings are not scattered by the harrow (Fig. 8). In general, however, it is not a sound practice to apply nitrogenous manures to grassland, as that particular element of plant - food contained in such manures is readily manufactured by the clover-plant in virtue of the nitrogen-fixing bacteria within the root-nodules. The clover-plant also manufactures nitrogenous foods not only in sufficient amounts for its own nutrition but .in excess, the surplus being soon made available for the grass with which that clover is , growing.

Again, apart from the benefit as a food-producing companion, the clover content of a pasture is valuable from the fact that the surface layer of soil is shaded and kept moist by the close leaf cover (Fig. 9),

and, as has been pointed out, this fact makes possible a greater surface-root production by the grass, which is so essential to its proper nutrition. This state, of course, may be secured by plants other then clovers, but the principle is the same. Plants inclined to tussock become exposed, with consequent ill effects owing to drying out, &c. Thus the mixed pasture should be the aim of the farmer.

MIXTURE FOR FIRST-CLASS LAND.

The following is a good general mixture recommended for the sowing-down of permanent pasture on the type of first-class country here referred to : Perennial rye-grass, 15 lb. ; cocksfoot, 10 lb. ; crested dogstail, gib.; timothy, 3 lb. ; Italian rye-grass, 4 lb. ; red clover, 3 lb. ; white clover, 2 lb. : total, 40 lb. per acre.

(To be continued.)