AUTUMN TOP-DRESSING.

Auckland Star, Volume LXI, Issue 72, 26 March 1930, Page 19

AUTUMN TOP-DRESSING.

gEAVT APPLICATIONS BEING MAD2S. : increased use of nitrogen. : (Specially Written by SUPER.) banners fare already busy with the autumn Applications of fertiliser, and: in a recent; visit to the Waikato, the vrite r found , that heavy applications were the rule, 2cwt and 3cwt per,acre being commoli. . Judging by the farms he 'saw, superphosphate was easily the most popular pliosphatic manure, but in Taranaki the' position would possibly reversed, and basic slag stand on top. One thing seems apparent and that is that greater quantities of North African phosphates are being used this year/ These, are of course finely ground, and for. rock phosphate arc fairly soluble, but it is difficult to understand why they should be popular when superphosphate which is so much more soluble, is available at reasonable prices. Basic slag, of course, suits a particular type of country, and is, therefore, favoured by many farmers, although its unit cost in New Zealand is usually above that of superphosphate, due mainly to carriage from overseas. In districts where topdressing is more or less in its infancy, a dressing of 2 to 3cwt of phosphate twice, a year sounds far tQO liberal, and farmers there are content with about half these quantities. \ll experimental work 'so far conducted in the Dominion goes to show that we haven't yet got to the sta'ge where a dressing heavy enough to bring into play the law of diminishing returns is given. It may he taken, therefore that a 2 to 3cwt dressing at this time of the year ig absolutely sound, and that the beneficial effects will be experienced in increased feed to carry on to the winter. Slag or Super? In most cases, of course, the farmer ■will have settled already, the question "ag to whether superphosphate or basic slag should be applied, but for those -pflio are in doubt, a few points may prove useful. The position is that in England, slag, generally speaking; is more favoured for grassland manuring that, superphosphate, probably because of the wetter conditions prevailing, and the heavier nature of the soil. In New Zealand the best returns (in experimental work) have usually been achieved by superphosphate, and this is easily *lhe m<sst popular phosphatic farmers. • The position is very cleanly and forcefully put in a recent book by Professor R. G. Stapledon, who says: "The results of recent grassland experiments seem to point /to the fact that' whilst the less soluble low grade basic slags and the . comparatively cheap ground mineral phosphates are as - effective as any. other phosphates on heavy wet land, or in districts of high rainfall, it is advisable to use more soluble phosphatic manur'es on drier types of soil. Basic slags of high solubility are on the whole as satisfactory as any other phosphate even on dry land, but when a farmer can obtain no information on the citric solubility of a slag it is advisable to fall back at any rate for a portion of .the phosphate on superphosphate. Slow returns from a cheap insoluble manure are not neciessarily the most profitable." He adds that an application of lime with superphosphate gives better results—a point worthy of notice here, where liming is given all too little

In order to appreciate the statement quoted above, a little knowledge of the position in England is needed. The position there is that there are large quantities of cheap slag available from steel-works, and the unit, cost of slag is considerably , below the unit cost of superphosphate. In New Zealand the position is exactly reversed. Here, the unit .cost of slag is above the unit cost of super. In England filag. has given the * best j all-round results on grassland; in New; Zealand the. , best returns have accrued from the use of super. : The Use of Lime.

Farmers who are using African rock phosphates in dry districts are likely to be disappointed with the results —in wet districts they may be quite satisfactory. The need for lime is recognised to a much greater extent in England than it is in New Zealand, a fact which explains the reason for some of our troubles here. Superphosphate will, give better "results if liming is regularly carried-; out, and except where farmers are considerable distances from railheads, ,i|' should not be very costly "to • give;afoapplication of lime once every two seasons. There are very few of our intensively farmed dairy farms which would not benefit-by an application of half a ton of lime to the acre, alid it would' then be found ,that, superphosphate would give an even better response than before. Basic superphosphate supplies lime of course, and where cartage is a .problem, this is perhaps the best way to obtain the needed lime. - The writer was surprised to find the extent to, which nitrogenous manures are being used in the Waikato this autumn, and the number of farmers who . intend giving applications during the next two months with the object of getting good winter feed. The experiences °f many of those who used these manures earlier in the season are interesting and show that these have their place in the topdressing programme. They must come after phosphates, however, and lime' is also necessary, and possibly potash. They ; will work • in admirably with our dairying system, which aims at concentrated production grass as early and as late in the season as possible. They have' distinct possibilities, too, in the case of the small ' sheep farm, and they may . assist in J doubling the carrying capacity of this type of land. Meantime, reliance on phosphates and the use of good solid dressings, will be found.sound farming : practice. t