FIELD WORK

Rotorua Morning Post, Volume 3, Issue 635, 13 September 1933, Page 2

FIELD WORK

TiGP-DRESSIN G IN RELATION TO PASTURE GROWTH. SEASONAL ADVICE. An important matter which requires some consideration this season is the relation between judicious top-dress-ing and the provision of special feed for use during the periods of naturally low production from pastures. In the minds of many there seems to be a belief that top-dressin'g, when skilfully exploited, may be employed to level out, to a material extent, the production from grassland from season to season land thereby increase the amount of dependence wbich may safely he placed on pastures as a direct and immediate source of feed. Actually, as a rule, top-dressing of ia type Which is commonly accepted as economically sound dntensifies the need for the proyision of feed t o supplement that which becomes immediately available from pastures from pionth to month- Diiring recent years this matter has been carefully investigatcd by the Department of Agriculture. The investigations indicate that fertilisers may be used profitably in a way which' will bring about inereased growth of grassland during winter and other periods of low growth, but the same investigations indicate further that the extra growth at slack seasons has not given any substantial assistance in bridging the awkward gap between the periods of high production and of low production of grassland. Experimental Work. As an illustration of this it hhs been found in experimental work that summer and autumn applications of superphosphate both roughly doubled the ' production of pastures during the period May to August. Such an increase in winter production expressed relatively in the above manner seems quite substantial. But the winter growth. without top-dressing is so slow that the increased growth due to top-dressing when considered absolutely is not impressive. The point of special interest in the present connection is that while the same summer and lau^umn applications. considered had not nearly doubled the growth in the following late spring and summer, yet the increase obtained in the' latter period, expressed in actual weight, was about five times as gre'a.t as the winter increase. Hence such top-dressing, although it increased winter growth, actually widened the gap between th'e production of winter and that of late spring and summer. And this despite the fact that the comparative differences in the rate of pasture growith throughout the year were levelled out to some extent. A greater levelling out in production of pastures occurs from similar top-dressing nnder milder climatic conditions than .those ohtaining in the experimental work under consideration; but conversely a similar levelling out may occur under more severe climatic conditions, and sa it is of moment that the conditions of the experiment work just considered approximate in essential respects to those ohtaining in the major portion of those distriets in which igrass farming is specially prominent. Nitrogenoug Fertilisers. During recent years a good deal of attention has been given to the use of nitrogenous fertilisers such as sulphate of ammonia for the purpose of stimulatino' growth during the off season of pasture production, fromething can undouhtedly he achieved in this way but it is stric'tly limited in amount. For instance, while application of sulphate of ammonia or similar nitrogenous ; materials in late July or August may be expected t0 stimulate growth in August and September, yet, as with phosphatic manures already mentioned, even if growth is doubled, the increase in feed thereby provided may be expected only partly to remove the shortage. Further, nitrogenous top-dressing has been found not to greatly iniluence growth in May, June and July. Hence the useful influerice of nitrogenous top-dressing is considerably restricted in duration, and while there is a possibility of employing nitrogenous fertiliser to lessen the gap beiween the periods of high and of low; production, it normally may be expected to leave a large gap still to he bridged. Good grazing management, _ especially dn early summer, has been found of value in levelling out the rate of pasture growth throughout the year; but it cannot serve to effect materially the rate of growth in winter land early spring — the period most earnestly calling for adjustment. Weakness in Grassland. To sum up, the fundamental weakness in grassland ias a direct shurce of stock feed is the occurirence of critical periods during which the rate

of growth of pastures is rejatively low. A system of grass farming ' which which depends wholly or prin--cipally upon top-dressing and sk'ilful * , igrazing- management to rernedy. weakness jg. mtrins.ically unsatisfactory in. feeding- .stock, the economic production .of which suffers froni . ■ periods of shortage of feed — which ' markedly is the case with dairy, cows 1 and breeding ewes. The only known economically sound way of h'aving feed supplies to meet j requirements . from time to time throughout the -year is along the line of. practice such as ensilage and the growing of special crops, of which ; mangels, lucerne, chou Moellier, car- i fots and turnips are typical. The circufnstances on certain farms may jgive rise to exceptions to this genera- ' lisation, but these exceptions are so . few as not to effect its validity ias a statement of the grassland position in igeneral. • . Einsilage and Cropping. Both ensilage and special cropping' can be made potent in putting the ' stock feed position' on a sonnd basis frqm one end of the year to th'e other. They are not, as some seem to believe, rival means of attaining the one objective. In other words, as a rule, a farmer should not ask: "Is it better ' to use ensilage, or is it better to employ special cropping in order to make provision for periods of scarcity of feed from pastures?" Generally the best farm management consists in exploiting both ensilage and special cropping. Ensilage servihg as a supplement, not as .an alternative, to spe,ci'al cropping, will in a great numher of cases give more attractive results than ensilage alone or special cropping alone. Seasonal Top-dressing. The application of phosphates to a pasture sh'ortly after it has been sown usually is sound economically. Under conditions of abundant rainfall the additioU of a small amount, say, not more than lcwt an 'a.cre, of quick-acting nitrogenous material to the phosphate may be worth while if cold conditions prevail. Such topdressing tends to give the seedlings additional vigour which is likely to sassist them usefully in passing through the delicate young stage. It is to be noted that there is some ground for helieving that the use of sulphate of ammonia on newly-estahlished p'astures may deleteriously affecf clover estahlishment. Such an effect is unlikely to he of moment in conditions which normally give a wealth of clover in swards; but when experience lea.ds one to expect normally a scant content of clover then any practice that may possibly reduce the clover should be viewed with caution. Top-dressing in September of establish'ed pastures which have not as yet been dressed will secure extra growth; but such top-dressing cannot he reeommended without reservatipns; if there is promise of an adequate supply of pasture growth for all re'quirements up to Christmas, including ensilage and hay, ithen the case for September top-dressing is definitely we'ak. Generally, fields which are to he set aside for ensilage or hay should be top-dressed just hefore they are closed from stock if fertiliser has not ibeen applied to them fairly recently. Such' top-dressing is likely not only , to': increase both the quality and the quantity of the hay or ensilage-, but also to reduce the cost of harvestin-g a ton of it.