656 PROCEEDINGS OF SECTION K. 



It appears possible, however, from more recent researches of 

 the same author {Memoirs Dept. Agric, India, Chem. Series, Vol. 

 1, No. 10, page 230) that the decrease in the transpiration ratio 

 when suitable manures are added is due rather to the more vigorous 

 growth of the plant than to any specific action of the manure on 

 the transpiration ratio. 



Dr. Leather has, at all events, shown this to be the case with 

 superphosphate, which, when supplied to a soil known to have no 

 need for phosphatic manuring did not lower the transpiration 

 ratio. 



This, however, is a case in which it is possible to confuse cause 

 and effect. The soil in question was unusually rich in available 

 phosphoric acid, containing more than three times as much as the 

 richest of the other soils, and it is not impossible that the transpira- 

 tion ratio was affected by the presence of soluble phosphoric acid in 

 the soil. 



J. W. Paterson {Journal Dept. Agric, Victoria, Vol. 10, page 

 349) has published results of experiments to determine the tran- 

 spiration ratio of oats, which are of interest in this connexion, 

 although the question of the effect of manuring does not enter into 

 the investigation. He finds the transpiration figure for this crop 

 grown in pots, and partially shaded during the period of their 

 growth to be about 483, that is to say, 483 tons of water are trans- 

 pired for every ton of dry crop produced. He assumes that for 

 plants of moderate development grown in the open air in Victoria 

 this figure would be 700 as against 870 in India (Leather, loc. 

 cit.); 522 in America (King); and 665 (Wollny), to 376 (Helle- 

 riegel), in Europe. 



According to Leather, a 13 bushel crop of wheat (about 1 ton 

 grain and straw) will transpire 693 tons of water (or 6.8 inches of 

 rain) per acre in India. Dr. Paterson states that local conditions 

 indicate that about 600 tons of water (6 inches of rain) per acre 

 would pass through a 13-bushel crop of wheat during its growth 

 under Victorian conditions. This estimate is not, however, sup- 

 ported by experimental figures, and it is to be hoped that Dr. 

 Paterson will be able to continue his investigations so as to in- 

 clude the determination of the transpiration ratio of an average 

 wheat-crop grown in the open under ordinary conditions, since 

 the question is one of the very first importance in wheat-growing 

 in Australia, and in establishing the geographical limits within 

 which wheat-growing can be successfully carried on with us. 



The subject of soil physics is much too wide to come within the 

 scope of an address like the present one, but I have been tempted 

 to draw attention to the possible influence of fertilizers on the 

 movement of soil-moisture, because of the very great importance of 

 the study of moisture conditions to us in Australia. In this con- 

 nexion, an interesting investigation has been carried out by Dr. 

 Heber Green and G. A. Ampt {Journal Agricultural Science, 



