MANURING GRASSLAND

New Zealand Herald, Volume LXXI, Issue 21765, 3 April 1934, Page 14

MANURING GRASSLAND

INTENSIVE MANAGEMENT MODERN TRENDS OUTLINED The use of nitrogenous fertilisers on permanent grazing land is a post-war development. Until recent years the improvement of grassland was carried out by the use of phosphatie fertiliser, couplied with hard grazing. Nitrogenous fertilisers were withheld from this part of the farm on account of the bad nfter-cffccts which had been noticed in earlier experiments. These, according to a pamphlet on " The Improvement of Grassland for Dairy Stock," originally appearing in the Journal of the British Dairy Farmers' Association, were due to a very large extent to a lack of knowledge of tho correct use of the fertiliser and the type of management which should accompany it rather than to the fertiliser itself. In order that nitrogenous manures may bo used successfully on grassland, tho pamphlet points out, two essential precautions must bo taken —(1) the nitrogenous manures must be carefully balanced by suitable applications of phosphates, potash, and on acid soils, lime; and (2) the herbage must never be allowed to get rank or out of hand, but be grazed or removed at an early stage in its growth. Thus it becomes necessary to apply annually in the autumn 2-Jcwt. to 3cwt. superphosphate or basic slag and 2cwt. 30 per cent potash manure salts per acre. In addition, the treated jtroa must be closely grazed at tho right time. This necessitates the subdivision of the area into small paddocks of from six to eight acres, and concentrating a large head of stock on a paddock for a short period, and then removing the stock on to another paddock. Nitrogenous Fertilisers

A continuous growth of grass is maintained on tho plots by periodical applications of nitrogenous fertilisers throughout tho season, amounting to a total of about 3cwt. nitrogenous fertiliser per acre per annum. It is pointed out that in this system two factors arc contributing to any improvement that may be brought about —(a) the fertilisers applied; and (b) intensive grazing. It has been shown that the system will double the stock-carry-ing capacity of average grassland, and, while a proportion of credit for this increase must be given to the fertilisers, credit must also bo given to the great improvement that may be brought about by intensive grazing, even if no fertilisers are used.

The system, it is suggested, may be of great value to a dairyman near to a town, who wishes to increase the stock-carrying capacity of his holding, hut is unable to acquire more land; and it may bo usefully employed in other special cases, but anyone contemplating embarking on tho 'scheme should bear the following points in mind: (1) The expense of fencing and laying on water to tho plots. (2) The annual cost of the fertilisers. (3) The necessity for an increased head of stock to deal with the increased production. (4) The effect of season; all grassland, whether or not managed intensively, is adversely affected by a prolonged drought or continued cold. However much manure is applied to grassland, the grass will not grow without a sufficient degree .of warmth and moisture. (5) The system will produce a superabundance of grass at a time of the year when, under normal conditions, there is an abundance, and when in any case it is difficult to keep under control. (6) The system will prolong the grazing season. Particularly will it stimulate the growth of grasses and clovers early in tho spring, provided climatic conditions are not too unsuitable. (7) Tho grass produced appears to be highly nutritious, bo far as our present methods of analysis permit us to examine it; but tho system restricts the ilora, more particularly tho miscellaneous herbs and clover. In these circumstances, it is desirable that animals should be allowed on tho intensive plots for a limited part of the day, and spend the remainder of the timo on some rough open grassland or in the sheds. Tho Strip System Special attention is directed to the " strip system," which is described in detail by Keeblo in his book, " Fertilisers and Food Production." The fol.lowing paragraphs from this book illustrate the system in a general way: - —" There are 20 cows to graze, and there are two fields each of nine acres set aside for them. One is dressed with fertilisers for early grass. One-third of the other, a strip at one end, is dressed a little later on, and will, therefore, be ready about ten days after grazing began on tho first field. So soon as the cattle have been taken otl' it a half or third of the first field is again dressed with nitrogen. The grass responds quickly. Tho cows find enough keep on tho nitrogen and nonitrogen parts of the second field until the first, field is ready to be grazed again. The cows return there, and then another strip or the whole of the remainder of the second field is dressed with nitrogen. So, by careful attention to the times of application of nitrogen, there is always some young grass for grazing. " There is no need to wait till the cows are oil a field before dressing a part of it with nitrogen. The cows take a lick, leave it, and do not return for at least a week. Statements are sometimes made that the nitrogen fertilisers commonly used arc apt to prove harmful if licked up by cattle or sheep. Investigation proves that the statements are without foundation." Encouraging Early Growth 10veil with this system it is, of course, necessary to see that the soil is well supplied with phosphates and potash and 1 imo where necessary. The system for the provision of early bite (that is, encouraging tho earlier growth of grass in the spring) has arisen directly from the intensive system, and it has been found that, provided certain precautions are adopted, nitrogenous manures can be used with advantage on certain gra:f. fields. The production of " early bite " is most desirable, but it must, be remembered that only one or two fields should be utilised for this purpose each season; also the same fields should not be used each year, otherwise they will become very rank and weedy. Tho grazing of the* early bite obtained should not bo too severe, otherwise the field may take a. long time to recover. Only a good grass field, in good heart and well supplied with good grasses, such as perennial ryegrass and clovers, should be used.