SEASONAL NOTES.

New Zealand Journal of Agriculture, Volume 54, Issue 1, 20 January 1937, Page 49

SEASONAL NOTES.

THE FARM.

Subterranean Clover.

During recent years attention given to field experience in New Zealand with subterranean clover has resulted in a considerable knowledge of its value in our farm economy and its appropriate management under various conditions. It has been established that subterranean clover may be made of outstanding value under a wide range of conditions of soil and climate. The position in the North Island in this respect is discussed elsewhere in this Journal. In the South Island the results of pioneering work described by Neave and Hewlett in the September, 1935, issue of this Journal has been repeated in essential features elsewhere, and the current available information points to the future development along the drier eastern portions of the South Island of what may be called a “ subterranean clover belt,” on account of the fact that subterranean clover will hold a key position in building and maintaining the fertility and production of the belt. A similar belt along the drier eastern portions of the North Island is already in its early stages of formation. The utilization of subterranean clover in the drier eastern portions of New Zealand promises to parallel to a large extent what has been done in correspondingly dry portions of Australia. The outstanding value which has been shown to attach to subterranean clover in certain of our drier areas is due primarily, to two facts : (1) it is a broad-leafed edible palatable legume, (2) it is a freely reseeding annual the vegetative activity or growth-period of which naturally coincides with satisfactory supplies of water in the soils, and largely avoids inadequate suppliesthe plant is vegetatively dormant only for some weeks during mid-summer, and it is during this period that the supplies of soil moisture are normally lowest. Its being a legume ensures not only that it is practically independent of supplies of nitrogenous matter of which the extensive open soils of the dry eastern districts are so deficient as to be uhable, as a rule, to produce economic yields of most other crops, but also that the content of nitrogenous organic matter of such soils is increased relatively rapidly by thriving crops of subterranean clover. As a result the general fertility of such soils becomes so improved that eventually they become capable of supporting successfully plants of high requirements in respect to fertility, such as perennial rye-grass and cocksfoot, which could not be grown profitably on such soils in their natural state. Its being a broad-leafed edible palatable clover makes it an appropriate component of the rations of milk-producing stock, be these sheep, cows, or pigs, and its high value for such stock has been demonstrated. Subterranean clover, being an annual which freely resows itself, becomes, for practical purposes, a perennial crop with which is associated the low cost of annual upkeep that is found so attractive economically in those crops such as prolific permanent pastures and lucerne in which establishment costs are spread over the production of a series of years. The standard of natural or unimproved production of the soils of the eastern districts on which subterranean clover is being used successfully is so low as to discourage greatly the culture of any crop calling for relatively high annual cost of upkeep such as is almost necessarily linked with frequent sowing of crops. Prior to the use of subterranean clover no satisfactory method of substantially improving such soils fairly rapidly has been practised.

The fact that subterranean clover when suitably nourished and utilized normally provides leafy, very nutritious feed during most of that portion of the year between late summer and the following mid-summer is indicative of its potentialities in both sheep-farming and dairying. It provides leafy feed for practically the whole period during which such feed is especially required in fat-lamb production. The gap in its production in summer is of importance in dairying : a measure that is effective in assisting to bridge this gap is . the provision of an area of lucerne under conditions suitable for lucerne culture—lucerne produces well just when the production of subterranean clover is at its lowest. - Outside the relatively arid areas of about 30 in. of annual rainfall or less, subterranean clover has . proved valuable especially because of its production, from autumn to the following spring inclusive, on poorish somewhat heavy soils, as well as on open soils. A fairly wide field experience in the sowing of subterranean clover can now be drawn upon. Only a very limited amount of spring ' sowing has come under notice, and this has not been successful. On the basis of results, late summer or early autumn sowing rightly is favoured. Usually, if not always, successful results have been linked with the application of phosphates which may be considered essential in the most profitable use of subterranean clover. On worn, open pastures success has followed .the broadcasting. on the surface of 1 lb. of seed an acre'; under similar conditions better and quicker returns have been obtained from increasing the seeding to 2 lb. an acre, and it is considered that still more attractive economic results are obtainable under the same conditions from the use- of up to 4 lb. an acre of seed, although on this point no definite data are available. Surface broadcasting of . seed in poor but nevertheless compact swards has on several occasions given disappointing results, and .when ploughing of such swards prior to the sowing of subterranean . clover is practicable it is recommended. Because of the difficulty of keeping white clover in a pasture dominated by paspalum, it is at times advisable to introduce into such a pasture subterranean clover, which serves usefully in conjunction with paspalum. Hence when a special paspalum pasture is being established it is as a rule advisable to include -J- lb. to 1 lb. of subterranean-clover seed an acre. Much greater quantities of subterranean-clover seed, ranging up to 6 lb. or 7 lb. an acre, have been used in conjunction with paspalum, but whether they are justified seems to be a matter of opinionthey may be expected to lead to quicker prominence of the subterranean clover. On light country in eastern districts of the North Island, 2 lb. to 5 lb. an acre of subterranean clover have been added with beneficial results to practically standard seed-mixtures for permanent pastures suitable for such land ; the tendency is to favour the larger quantities 'of subterranean clover. For the purpose of obtaining special subterranean clover areas, 5 lb. to 10 lb. an acre of subterranean clover sown alone or in conjunction with 20 lb. to 30 lb. an acre of Italian rye-grass has given good results. In Canterbury, on the farm of the Canterbury (N.Z.) Seed Co., Ltd., near Leeston, a mixture of to lb. to 12 lb. of cocksfoot and 2J lb. to 3 lb. of subterranean clover an acre has proved quite satisfactory. Experience suggests for the West Coast of the Wellington Province and for localities with similar conditions the use of 2 lb. to 4 lb. an acre of subterranean clover, both for broadcasting on ' existing swards and for inclusion in mixtures to be sown on cultivated ground. The tendency to favour.the larger amount of seed increases. As in the eastern districts of the North Island, for obtaining quickly a special • subterranean clover area the use of 5 lb. to 10 lb. of . subterranean - clover seed an acre is considered advisable. Specific guidance about the use of subterranean clover under particular conditions and for. particular purposes is obtainable from local officers of the Fields Division.

Autumn Top-dressing.

On many farms some at least of the pastures advantageously may be dressed with phosphates in February or thereabouts. When the supply of moisture in the soil is sufficient to admit of growth, then the application of phosphates at the time mentioned usually increases the leafy growth of pastures from shortly after the phosphates are applied until well into the beginning of winter. Hence the feed position during the critical winter and early spring period is strengthened. Further, during the following spring and summer, the stimulating influence of the phosphate continues, although not so intensely as if the phosphate were applied in the winter or early spring. Hence the application of phosphates in the late summer or early autumn tends to a more even growth of grass throughout the year than does the spring application of phosphates, and therefore efficient grazing management of pastures can be obtained more easily under autumn application than under spring application of phosphates. It should be borne in mind, further, that both autumn application and spring application of phosphates increase the absolute gap .between the peak of high production and that of low production of permanent grassland, and that both therefore intensify the need for provision of special feed for use during the critical periods in which the amount of feed directly available from grassland is customarily, below the current requirements of the stock, unless substantial under-stocking is practised. Preparation for Autumn Sowing of Pastures. On many farms a summer task of prime importance is the preparation of ground for the autumn sowing of pastures. In this task many seem to appreciate but imperfectly the great value of thorough cultivation in the production in the seed-bed of the fine firm condition which so usefully fosters successful establishment of seedlings. The value of firmness of seedbeds is indicated to some extent by the superior pastures that often are found along “ headlands ” of fields or along tracks where there is greater consolidation than in the remainder of the field, this being due to additional passage of stock or of machinery. The advisability of fineness in the seedbed may be realized readily by considering what must be the fate of many of the small seeds used in pasture-seed mixtures when the soil is in a coarse or lumpy condition : any of these small seeds covered by lumps cannot with their limited supply of energy push their shoots to the surface. In districts in which the ravages of the grass-grub have been much in evidence during recent seasons, it is. inadvisable to sow pastures in land which in the immediate past has been occupied by a cereal or by grass. On the other hand, the more land was without a plant-covering from November to December, the period in which the eggs which develop into the grassgrub are deposited in large numbers, the more likely is the land to be free from the grub during the following twelve months. Control of Pasture-growth in Summer. • Widely more attention than is given should be given to the quality of the feed which is provided by the pastures in summer. ■ This matter is of special importance in dairying. The crux of the position is the fact that the quality of the feed provided by pastures is governed to a large extent by the stage of maturity of that feed. Stemmy or woody growth such as results when flower-stalks are allowed to develop is of low feeding-value. This explains why, at times, the production of dairy stock falls off at an unduly rapid rate, or lambs fail to develop satisfactorily when the animals seem to be in the midst of plenty. Further, the development of flowering parts in pasture-plants not only leads to a considerable decrease in the nutritive value of the feed, but also is connected causally . with a considerable falling-off in the rate of growth :

it seems natural for plants which have flowered and matured to become . quiescent for a period, and during this period supplies of leafy feed may be undesirably scant. In February “ topping ” of pastures by light mowing may be advisable in the interests of feed-quality : in this “ topping ” the aim should be to remove merely the portions of the sward which are rank or producing seed, in order to stimulate the production of fresh leafy growth from the base of the “ topped ” plants. Somewhat close mowing, especially if the conditions at the time are dry or become dry shortly afterwards, may be definitely harmful. Appropriate mowing of pastures may also serve usefully at this stage to remove shade-creating parts of such weeds as docks, thistles, red-shank (willow-weed), and fat-hen. If these weeds are not dealt with they are likely to weaken greatly the pasture-plants in their vicinity, and probably to create vacant patches on which, later on, inferior plants become established. “ Topping ” in the manner just specified is likely to be especially effective in the production of leafy growth when it is carried out in conjunction with top-dressing as already discussed. Attention to such matters as “ topping ” and summer top-dressing is particularly advisable on the. part of those whose policy it is to depend more and more upon pastures for the feed for their stock. On the other hand the use' of such crops as soft turnips and rape, which are markedly low in woodiness and high in digestibility when used at an appropriate stage, offsets excessive woodiness due to overmaturity in the portion of the ration obtained from pastures. Only leafy pasture-growth, low in stemminess or woodiness and high in digestibility, can efficiently replace standard successful summer supplementary crops such as rape and soft turnips. Whether such leafy pasture-growth in practice can or should be made wholly to replace summer supplementary crops is a management problem to which probably no generally valid answer can be given, and about which we are not at present directly concerned.Work with Special Crops. The sowing of certain special crops in late summer is at times distinctly advantageous. For instance, land from which a cereal crop has recently been harvested if sown without delay in Italian or Western Wolths ryegrass (251 b. to 30 lb. an acre), and red clover (51b. to 61b.) usually provides autumn and winter feed that is likely to be distinctly useful, especially to sheep-farmers under Canterbury and similar conditions. The use of cereal crops as catch-crops productive of winter feed was discussed last month in these notes, which continue to be seasonable. If arable land is known to be foul with the seeds of annual weeds such as fat-hen, spurrey, and nightshade, which germinate in the spring or early summer moi;e freely than at other seasons, then the cropping of such land should be planned so that the land is sown in the autumn when the crop may be more likely to become established without the grave competition from such weeds against which spring-sown crops are almost certain to have to struggle. Young lucerne sown in November or December is often fit for mowing in February, but it should not be mown until flowering has commenced, unless weeds threaten to weaken the lucerne-plants by the shading that they cause. Mowing prior to flowering militates against the development of the root-system, and persistent sturdiness and heavy yield of lucerne is associated with an extensive root-system. Usually top-dressing lucerne with phosphates in summer profitably increases its vigour. ’ The effective use of special summer feed grown to supplement the pastures is of importance and is discussed in these notes in last month’s Journal, which suitably may be considered for current guidance.

—R. P. Connell, Fields Division, Palmerston North.