ROCK PHOSPHATES

Te Awamutu Courier, Volume 55, Issue 3940, 16 August 1937, Page 5

ROCK PHOSPHATES

THEIR USE ON THE FARM. INVESTIGATIONS PROCEEDING. The need for more critical research into the uses of rock phosphates in New Zealand was emphasised by Messrs A. W. Hudson, of Massey Agricultural College, and J. W. Woodcock, of the Department of Agriculture, in the course of a paper given before the annual conference of the New Zea land Grassland Association at Dunedin. "It is a matter -for regret that, in view of the importance of phosphatic fertilisers to New Zealand, no serious attempt has yet been made to carry out a thorough and critical study of the long range effects of phosphatic fertilisers on production and their fate in and effect on the soil,” they stated. “An average soil contains about 3,000 lbs of phosphoric acid in the top S or 9 inches. In the course of 50 years annual applications of about 160 lbs of Nauru phosphate or 300 lbs of superphosphate will add a further 3,000 lbs. In districts where such quantities are being regularly applied only a fraction is being removed in crops or by stock. What of the balance? For how long will such applications be necessary and remunerative? What, in the long run, is the best form in which to apply our phosphate? These are some of the questions with which we are already faced, and it is certain that the answers to these, which at present cannot be given, will be much more pressing in another 50 years.

"The only means whereby such questions can be answered lies in the establishment of absolutely permanent experiments under different conditions of soil and climate. Such data as is at present available in this country is provided by experiments of short duration only. The weight of such evidence favours the use of readily available phosphates. Long term investigations may emphasise their value still further, but one must not lose sight of the possibility that other forms of phosphate may prove more desirable over a long period of years. The point is that we do not know, and it is necessary that we should obtain the information.”