TOP-DRESSING.

King Country Chronicle, Volume XXII, Issue 2613, 11 August 1928, Page 2

TOP-DRESSING.

LECTURE TO MANAWATU FARMERS. SIR JOHN RUSSELL’S ADDRESS. The lecture hall at the Manawatu A. and P. Showgrounds was crowded on Monday last, when Sir John Russell, noted soil chemist, of Rothamsted, England, who is at present on an extended tour of the Empire, in the pursuit of his investigations, lectured on “The Top-dressing of Pastures.” Sir James Wilson occupied the chair, and briefly introduced the lecturer, describing him as a man possessing both scientific and practical knowledge. Sir John Russell first intimated that he did not propose to speak on New Zealand farming, as he was not really conversant with that subject, but that he wanted- to detail results that had been obtained in the English pastures through top-dressing under conditions somewhat similar to those in New Zealand. These pastures were very old, and the people there generally obtained good results from them —frequently to the extent of 600 or 700 gallons of milk to the acre. DISCOVERY OF FERTILISER.

In the old clays lime was the only fertiliser used for top-dressing, but it proved to be insufficient, and improvements had taken place on the flat lands, where it had been discovered that bone was a valuable and it was not long before an industry sprang up in this connection, while to-day it was still admitted that bones were one of the best means of improving pastures. This was the position when experiments had first been started at Rothamster 75 years’ ago. A plot of about 20 acres was cut up into different portions, and manured differently, and after two years it was noticed that the previous uniformity of the grass had disappeared. Sir John Russell proceeded to detail the experiments that had been carried out on the various plots, and stated that it had been discovered that various types of fertilisers had particular effects on the herbage, so that it had been learnt that both the quantity and the character of herbage could be affected by the use of fertilisers. Bad pasture could be made good ones by top-dressing, although in some cases the process took a long time, he said, but it was always an experiment to see if it would be more expensive to plough out the land and start afresh, or bring fertilisers into use. Basic slag had next been discovered. That was the next big improvement regarding top-dressing. It had been found that the value of the slag was the phosphate in it, blit there was some other value which had not yet been discovered. Prior to the war there had been only one type of basic slag on the market, but when the process of steel making changed during the war, so did the slag, and in 1918 there were three types on the market. The respective, value of these types had been investigated, two having been found to have high solubility and one to have low solubility, and the more valuable was undoubtedly that which had the high solubility. The speaker proceeded to deal with the effects of this fertiliser on pasture, dealing particularly with white clover. The improvement due to slag caused a great demand for it, and the supply was somewhat limited. Experimenters then found other fertilisers which would produce similar efforts, the result being that- superphosphate and mineral phosphate were brought into use. The superphosphate encouraged quick growth, especially of clover, the experimenters found. It had been learnt that neither superphosphate nor basic slag washed out of the soil very readily, although at Rothamsted no evidence had been obtained that the phosphate ever worked out. Where the rainfall was heavy, and where the soil was light, it was safest to assume that a certain amount did wash out. The general result of experiments he had had to do with, said Sir John, was that best effects were produced with light dressings, but on that problem it had been impossible to make a general rule. The only way of finding out what would be the most profitable dressing to use was to experiment under the particular conditions required. MINERAL PHOSPHATE. kind of phosphate coming on to the market was mineral phosphate, which was not quite so good as either superphosphate or basic slag, but it had been found that when it was ground fine enough to pass through a sieve of 120 meshes to the inch, it acted fairly well.

There had been two distinct cases, said the lecturer, where it had been found that phosphates as fertilisers had been useless, but once lime had been used on these acid soils the phosphates had acted well. Dealing with potash fertilisers, Sir John said that the same success as had followed the use' of phosphate had not been met with, save in two or three, cases surrounded by set conditions, but as a ride it was found that potash was not very necessary on farming lands. Where a light, sandy soil was met with it would be found that potash encouraged the growth of grass. “Generally speaking we find that light soils are best for potash,” he said. NITROGENOUS FERTILISERS. Nitrogenous fertilisers were next dealt with by Sir John Russell, who stated that as a general rule sulphate of ammonia resulted in a greatly increased return of hay, in some cases to an extent of 20 cwts. to a cwt. of the fertiliser. The same applied to nitrate of soda, but in both cases too much, or too regular, a use of the fertilisers had a harmful effect. The speaker dealt at length with the effects and methods of using these fertilisers on various types of land, stating that the management of pastures was quite as important as the top-dressing. No matter how perfect a top-dressing was given, its effects would be nullified were the management not good.

It had been found that good results came from the cultivation of the pastures, and on the grass lands at Rothamsted the harrows were put over the fields early, thus giving the roots more air, while in some cases discs performed the same -work. Shelter belts both for grass and animals were useful, and it was surprising to find what beneficial effects were obtained in wind-swept country by providing a little shelter in the shape of hedges and trees. Drainage was also an important point to be considered in the farming of good pastures. The lecturer proceeded to state that there were many problems concerning pastures that were still unsolved, and concluded by saying that he considered that the Manawatu district was fortunate in having the Massey College, where experiments could be organised and carried out on a large scale. (Applause.)

Sir John Russell was accorded an enthusiastic vote of thanks on the motion of the chairman.