10 Oct., 1918.] The Residual Effect of Superphosphate. 611 



phate has become a valuable industry, supporting a number of workmen, 

 who, in turn, help to create a better demand for farm produce. The 

 increased production following on the use of fertilizers also suggests the 

 possibilities of other discoveries by which greater yields may be won 

 from the soil, and offers encouragement to those interested in the 

 advancement of the science of agriculture. 



On the occasion of his visit to Werribee with the members of the 

 British Association for the Advancement of Science, in 1914, the late 

 Dr. T, S. Hall said, " The agricultural problems in Australia awaiting 

 investigation are enormous, and for the solution of these problems the 

 experience of the Old World is of little value. There is great necessity 

 for experiments being conducted towards the development of a system 

 of farming that will meet local soil and climatic conditions." 



While the progressive farmer has become fairly well acquainted Avith 

 the benefits accruing from the rational use of superphosphate, and desires 

 further knowledge regarding its effect on the soil, there are many 

 " beginners," and probably some sceptics, who still require enlighten- 

 ment on the elementary facts relating to its application and on the scope 

 for greater and more profitable use of fertilizers than obtains at 

 present. 



Experiments at the Werribee Research Farm. 



If the inquiries made from time to time at the State Research Farm, 

 Werribee, afford any indication of the points about which advice is 

 required, the following would probably be amongst the most 

 important : — 



1. What is the "best'' quantity to apply? 



2. What is the effect of the continuous (from year to year) 



use of superphosphate ? 



3. What is the " lasting " or residual effect of superphos- 



phate, and does it " leach " out of the soil, " revert," or 

 become unavailable as a food for plants? 



Such pertinent questions indicate a keen desire for knowledge on the 

 subject. The first question has been dealt with from time to time in 

 this Journal, and may be tested on private farms ; reliable theories, 

 together with some information, based on practice, can be advanced in 

 regard to the second question, but until the last few years little or 

 nothing had been done in Victoria to settle the important matters raised 

 by the final question of the residual effects of superphosphate on succeed- 

 ing crops, pasture, &c. Though it is known that crops do not always use 

 the whole of the plant food contained in the fertilizer applied to them, 

 in practice it is not often possible to obtain definite or reliable informa- 

 tion, especially of a comparative nature, regarding the residual value or 

 effect of the fertilizer on succeeding crops. The varying seasonal con- 

 ditions and ordinary farm practice generally prevent the observer 

 arriving at a conclusion more definite than an " expression of opinion " 

 that the result was beneficial or otherwise; and as a field experiment to 

 test the matter necessarily extends over a long period, and entails con- 

 siderable labour and expense, the investigation comes within the province 

 of the Experimental Farm. The State Research Farm at Werribee 

 was established to undertake such work as this, and amongst the many 



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