PHOSPHATES.

Wairarapa Age, 5 June 1930, Page 5

PHOSPHATES.

FOUNDATION OF PROSPERITY IN NEW ZEALAND.

IMPORTANCE OF ENSURING FUTURE SUPPLIES.

ADDRESS BY MR. L. J. WILD.

Some very interesting observations on the supply and use of fertilisers in New Zealand were made by Mr. I*. J. Wild, Principal of the Feilding Agricultural High School, in an address to farmers and others at the Winter Show yesterday. Mr. J. H. Handyside presided over a large attendance. Mr. Wild particularly stressed the importance of doing everything that was possible to ensure that adequate supplies of phosphatic manures should be available to this country as time went on. Of the three chief fertilisers —phosphates, nitrogen and potash—Mr. Wild phosphates were by far the most important to New Zealand. There was every likelihood that the quantity of phosphates used in this country would increase largely and rapidly. Last year New Zealand imported upwards of 340,000 tons of phosphates, nearly five times as much as was imported in 1920. This country had 1,726,000 acres under crop and 16,855,000 acres in sown grasses (exclusive of native grasses). The time would come when every acre of sown grass land would get its topdressing. In England, ten cwt. of slag to the acre was regarded as a reasonable dressing. No fanner in New Zealand used such a quantity, but in the Waikato 5 cwt. in the course of the year was not regarded as too much. As compared with the amount of 340,000 tons of phosphate now imported, one cwt per acre on the sown grass lands of the Dominion would take 840,000 toffs per annum. In addition, some of the native grasses responded very well to top-dressing. The consumption of phosphates in Europe was four million tons in 1923 and six million tons in 1927. He did not know what last year’s figure was, but probably it would show a further large increase. The world consumption of phosphates four years ago was eight million tons. Nearly all the phosphate used in' Europe came from Africa. New Zealand obtained its supplies chiefly from Nauru and Ocean Islands. The Dominion had a legal right to 16 per cent, of the output from these islands, Great Britain and Australia each being entitled, to 42 per cent. Britain at present did not take her 42 per cent., which was divided meantime between Australia and New Zealand. THE NAURU SUPPLIES. Three years ago in Masterton, Mr. Wild continued, he had suggested that the time might come when Great Britain might want to have her share of the Nauru phosphate rock. At present ahe got her supplies from Africa, mostly from French territory, where political conditions were not altogether stable. If there were any interruption of these supplies, Britain might look to Nauru and Ocean Islands. New Zealand, for the last two years, had not been able to get enough phosphate from these sources and had imported some from Africa. The anticipated output with Nauru fully developed was one million tons and he suggested that the time might come when New Zealand would want 936,000 tons per annum. If it did, this amount probably could not be obtained from Nauru. The supply of phosphate to New Zealand at present was not by any means secure, and farmers and those who represented farmers in Parliament should be keenly interested in seeing that future supplies were secured. Agriculture was said to be the foundation of the prosperity of New Zealand. He might extend this by saying that phosphate rock was the foundation of the prosperity of New Zealand. The soils of this country from North Cape to the Bluff all lacked phosphate and all responded to its application. The only discovered source of supply in New Zealand was one in Otago, which yielded about ten thousand tons per annum. Our exports of butter, cheese, wool, meat, skins, etc., all took phosphate out of the country. Nearly four per cent, of the body of a bullock consisted of phosphate of lime. Every gallon of milk produced in this country contained half an ounce of the same substance. There was thus an enormous draining of phosphates from our soil. APPLICATION METHODS. As to the kinds of phosphates, one was bones and bone dust, a good fertiliser, but one that he thought had never been worth the prices paid for it compared with the prices of other materials that would give the phosphates required. Then came phosphate rock, of which Nauru and Ocean Islands were probably the richest deposits in the world. The raw rook was not soluble in pure water, but was comparatively easily soluble in soil water, which contained week acids. It was essential that raw phosphate rock, used as a fertilising material, should be extremely finely ground. Another essential to the successful use of this material was a plentiful water supply and it was best used if the soil was naturally sour. —. By far the greater part of phosphate ' imported into New Zealand was converted into superphosphate (phosphate rock treated with sulphuric acid) which was largely, but not completely, soluble in water. The question whether superphosphate added to the acidity of the soil was one on which he had changed his ground, largely because the manufacturers had changed their ground. The superphosphate imported years ago had acid properties which appeared in the corrosion of drills and in other ways. The verdict of the Rothampstead Experimental Station in England, however, was that superphosphate as it was now manufactured, did not add to soil acidity. Modern superphosphate was a greatly improved material. In New Zealand soils, where lime was absent there was usually iron and in soils containing iron superphosphate tended to waste. That made it advisable to use superphosphate in conjunction with or with finely ground raw phosphate rock. Mr. Wild illustrated his observations with experiments in which he first of all filtered a solution of superphosphate. The filtered solution was clear, but with the addition of lime water it clouded, the lime and soluble parts of the superphosphate forming a precipitate. The addition of citric acid, as an approximate equivalent of the weak soil acids, once again cleared the solution, showing that lime and the soluble parts of superphatphate in conjunction were