GRASS GROWTH

New Zealand Herald, Volume LXXIII, Issue 22355, 28 February 1936, Page 16

GRASS GROWTH

ABUNDANCE OF FEED FUTURE OF THE PASTURE NEED FOR TOP-DRESSING In many districts there is a greater growth of pasturage than has been the case for many years. This has made up for the rather backward spring, with its subsequent poor production, which obtained over a large area of the North Island last year. The widespread growth and the higher returns' from dairy herds, combined with a considerably better price for butter-fat, will help considerably to restore the position of the dairyfarmer. The luxuriance of grass growth—particularly if it continues for a few weeks —might, however, mask the necessity for providing the dairy land with its annual autumn dressing of superphosphate. The advent of frosts will soon make the grass lose most of its milk-producing qualities and will also reduce the quantity available. A number of the most successful dairymen top-dress a considerable portion of their farm every year, irrespective of the condition of pasturage. In the dry autumn, when little growth is apparent, top-dressing goes on in late February and in March, the fertiliser awaiting the advent of the autumn rains. In an autumn such as at present, a certain percentage of the farm is grazed down, or the mower is used, and the fertiliser is applied. A little thought will reveal that spring, summer and early autumn growth is making a heavy drain on the pasturage, an 4 if this is to go into the winter in good condition and produce its maximum next spring, it must be kept adequately supplied with the right type of fertiliser. ®So far as grazing land is concerned, it has been amply demonstrated over a largo number of years, both by the results secured on dairy farms and by official experiments, that the autumn is the best time to top-dress a large acreage of the pastures on the farm. The herbage is making a fresh root system, and the application of soluble phosphate encourages this root system and helps the growth well into the winter. On most North Island soils root growth does not cease even in the winter, and while top-growth in the form of leafage is not very apparent, the plant is building up so as to come early in the following spring and to maintain a good growth over the months following. In the autumn the soil is warm and conditions are favourable for maximum growth. Furthermore, the effect of applying a fertiliser such a superphosphate is to increase the mineral content of the grass, which is so essential. Not many years ago. the most popular period for top-dressing grassland was in the spring. Undoubtedly spring appli-

cations give quick and very profitable returns, but they are suited in the main for the production of ensilage and hay. Autumn applications have been proved essential for highest production on the grazing lands of the dairy farm. The matter has been well stated by R. P. Connell, in the New Zealand Journal of Agriculture: "In the main grass-farming districts top-dressing with phosphates during the February-April period is widely advisable. One of the important advantages of such top-dressing is that it usually brings about, prior to the dormant winter period, an appreciable increase in growth, which is valuable because it assists not only in increasing the winter supply of feed, but also enables stock to enter the winter with additional vigour and condition which stands them in good stead in later critical periods. "A second material advantage of autumn top-dressing is that while it stimulates growth in the early spring practically to the same extent as would spring top-dressing, it is declining in its effect by the time summer is reached, and so does not cause such a rush of growth as does spring top-dressing—a rush which tends to intensify the practical difficulties in effecting satisfactory control of pasture growth in early summer." There seems to be every evidence that the autumn top-dressing is rather superior to winter, as according to Professor Stapledon, the world authority on grass production, it is better to applv fertiliser when the root growth is fairly active, as in the autumn, rather than in the dormant period of the year when there is a greater danger of the fertiliser applied being locked up in an insoluble form in the soil before the plant can get its full supply. The Department of Agriculture, _in its summary of the current position relative to top-dressing, says:— (1) Over wide areas top-dressing reduces substantially the fixed charges attaching to each unit of production. (2) Because of this, in much of that portion of the Dominion in which grass farming is dominant top-dressing may be expected either to make profitable farms more profitable, or to make unprofitable ones less unprofitable. While this statement relative to the value of top-dressing is generally applicable, it is subject to two important qualifications. One thing is that expenditure can be, and indeed often is. dissipated on injudicious top-dressing which gives unsatisfactory results. The other is that in some exceptional instances. occurring especially on land of low carrying capacity, top-dressing cannot be recommended. (3) The only way to ensure that topdressing is judicious is to base it on comparable field results. At times, instend of being based on such results, it is based on tradition or on experience gained under essentially different conditions or on unproved assumption in the guise of science. (4) In general, phosphatic top-dressing, being of basic importance, should first receive attention, but occasionally the need of lime or potash or of both may be equally acute. Summarising, it can be said that, while over the North Island there is an abundant growth of pasturage, this should not deter the dairy farmer from treating at least some of his pastures with the usual 3cwt. of superphosphate —or a little more, according to the class of country —during the autumn.