Minister’s information on urea questioned

Press, 17 August 1979, Page 16

Minister’s information on urea questioned

Lincoln College’s Professor T. W. Walker, professor of soil science, is interested in who is providing the Minister of Lands, Mr V. S. Young, with his information on urea and phosphate fertilisers. Speaking to farmers’ conferences in Oamaru and Balclutha he said that some of this information was so ridiculous that it could be coming from the same sources which encouraged the purchase of the surplus urea plant from the United States in the first place — this plant will use Maui gas. Professor Walker was commenting on statements made by Mr Young at a fertiliser seminar in Taranaki. Mr Young had said that urea was tne fertiliser of the future, said Professor Walker. It had, in fact, long been the main form of nitrogen voided on New Zealand pastures in the urine of grazing animals, which the notable New Zealand grassland scientist, Sir Bruce Levy, had called “liquid gold.” Synthetic urea had some merits. It was a highly concentrated nitrogen fertiliser which reduced transport costs, but for this very reason it created problems when small quantities of nitrogen were being applied. It did not mix well with other fertilisers. Under some soil and climatic conditions it quickly coverted to ammonium carbonate and much of the ammonia might be lost as a gas in the air. It might damage the germination of wheat when drilled with the seed at 100 kg per ha. It also contained no other plant nutrients than nitrogen. It might be asked if ammonium sulphate would be made at the new plant, because it comprised more than half of the fertiliser nitrogen that was imported. Would the import of ammonium phosphatebased fertilisers be prohibited? These attractive granular forms were being used increasingly for drilling with maize and other crops, and these and other forms of nitrogen fertili-

sets were better than urea for some purposes. Professor Walker said that he wanted to examine the suggestion that cheap sources of rock phosphate would, soon disappear and that in some mysterious way superphosphate could be replaced by urea. Nauru at present supplied 50 per cent of New Zealand’s phosphate and would continue to do so until the year 2000 at least. The remaining 50 per cent would be supplied in the immediate future from Christmas Island, which was rapidly pricing itself off the market, and the United States, Africa and the Middle East — whichever was the cheapest. Phosphate was different from oil. While world oil reserves were running out, there were vast known deposits of phosphate, including much in Queensland which the phosphate industry regarded as a guaranteed long term phosphate source for New Zealand. There would be phosphate rock available long after Maui gas had run out Professor Walker said that the inference that urea could be substituted for phosphate was quite nonsensical. If enough urea was used to replace all the nitrogen fixed by clovers in this country’s pastures it would be a case of thinking of some 2M tonnes of nitrogen a year, which was equivalent to more than 4M tonnes of urea. This would consume 75 per cent of the Maui gas and not the 3 per cent proposed. The use of nitrogen fertiliser did not remove the need for use of phosphate and other nutrients. If 4M tonnes of urea were used a year there would still be a need for about 2M tonnes of superphosphate to go with it, which was what was actually used now. This would give a ratio of 10 parts of fertiliser nitrogen to one of phosphorus, which was what the highly efficient Dutch farmer used at present. “The difference between us and the Dutch is that we get our clovers to fix about 10 kg of nitrogen from the air for every kg of phosphorus we use,

whereas the Dutchman pays for his nitrogen out of a bag,” said Professor Walker. “Perhaps this is why we can undersell Dutch butter and cheese in Europe after carting it half way across the earth. “Superphosphate is not only the fertiliser of the past, as it or something similar will be with us when Maui gas has run out.” It was good to be reassured that the costing of the urea venture had been very thorough, even if Mr Young could not give a “dollar and cents answer,” said Professor Walker. He had asked the Minister of Energy, Mr Birch, at the ECO annual conference in Wellington, if urea would cost the same whether the plant was working at quarter — equivalent of present usage — or full capacity. The answer was that his advisers said it would. “The Minister must have rather more confidence in his advisers than most of us,” commented the professor. There appeared to be much reliance on the sale of condensate oil, a byproduct collected during the process of using the gas. But should not this be accounted for in the price of the gas, however it was used, or was the gas to be sold cheaply at a subsidised rate for making urea? “It is difficult to see where we shall save substantial amounts of overseas funds,” said Profesor Walker. “The interest payable on the purchase price of the plant alone would buy most of the nitrogen fertilisers we now import. Only if we stimulate the use of more urea, particularly on our grasslands, should we save much in the way of overseas funds. This is exactly what the Minister of Lands, Forestry and the Environment is trying to do. One wonders if he is making a bid for yet another portfolio — that of the Minister of Agriculture, who is keeping remarkably quiet about the whole affair.” Asked if he had taken his case against the urea project to the Govenment, Professor Walker said he had not. It was too late. The decision had been taken.