USE OF FERTILISERS

Wairarapa Times-Age, 1 March 1941, Page 9

USE OF FERTILISERS

MEANS TO ENSURE BEST RESULTS AVOIDANCE OF WASTE. GRASSLAND TOPDRESSING. While it is always desirable to obtain the best possible results from fertilisers, this is particularly so now because of the effect upon our phosphate supplies of the recent enemy action at Nauru Island. The utilisation of manures so that the most economic results are obtained therefrom is largely a matter of common sense allied to a knowledge of manurial response on particular soils, states the Department of Agriculture in a bulletin. Under practically all New Zealand conditions for all crops some fertiliser should be sown, but the quantity and the type used vary with different’crops and with different soils.

In grassland topdressing waste may be avoided in several ways. In the first place, it is useless applying manures which yield no response. Lack of response may be due to various causes. Most New Zealand soils give no response to potash, though responding to phosphate. On the other hand, there are some soils which will not respond to phosphate without a dressing of potash and/or lime. Where two or more manures are required on one soil type to produce a response, it is accordingly wasteful to use only one of these manures. Since lime is readily available it should be used wherever an appreciable response is obtained by its use alone or in conjunction with phosphate and this is the case generally in the Wairarapa. Whatever the response on a particular soil, it is much more likely to be profitable to topdress good swards of grassland than* to topdress poor thirdclass pastures composed of flat weeds and grasses such as sweet vernal and brown top with little or no clover. The greatest returns usually are obtained from top-dressing the better class pastures which have a well balanced mixture of clovers and grasses.

The quantity of manure applied is important. Under light rainfall conditions a heavy dressing is wasteful although a similar dressing in a wetter district may give good returns. For most districts there is an optimum quantity to apply, lighter or heavier dressings giving a less economic return according to the law of diminishing returns.

The method and manner of application of the fertiliser is also important. If mechanical means are used it should be seen that the topdresser is working efficiently and giving an even spread. Similarly, if top-dressing by hand is employed, strict supervision of contract or other labour should be provided, since irresponsible labour may spread the manure thickly in some areas, leaving other unsown. The task of making the best use of fertilisers does not end once the manure is applied: The most important part is the utilisation of the growth produced by the top dressing. It is obviously unwise to apply manure and then to stock the area too lightly so that the pasture “runs away” to rough growth and seed heads. Nor is it wise to use on a top-dressed area the class of stock which will benefit least and give least return. Seldom, if ever, can the most profitable returns be obtained from outlay on top-dressing of grassland unless it is associated: — (1) With rational conservation of the pasture growth that develops as a surplus supply during periods of rapid growth of grassland, or (2) with the growing of special crops to provide reserves of feed during the customary periods of scant growth of pastures. In brief, the planning of farm work as a rule should provide for topdressing to be linked with haymaking or ensilage or special forage crop production, or indeed with all three of these measures whereby reserves of feed may be created for use either in late summer or in winter and early spring. This is the general rule to which there are some exceptions: Top-dressing may be able to stand on its own legs completely but a farmer should be sure that his case is an exception to the general rule before he ignores that * rule.

Advice in relation to all aspects of top-dressing may be sought from the district officer of the Fields Division. Department of Agriculture.