14 



food we have removed from it, the amount of plant food will 

 remain stationary. Mr. Hughes in his attempt to arrive at a 

 similar basis for Ceylon has taken into account the leaves that 

 drop off and the pulp and everything else. All these are returned 

 to the soil. Therefore they do not require to enter into the 

 calculation. But I do not recommend a reduction in manures. I 

 only recommend, and that most emphatically, the necessity for 

 experimenting with manures. I do not wish to lay before you 

 any facts and figures for reducing your bill in manuring. I only 

 wish to enlist your sympathies in the matter of experimenting, and 

 in order to do so I have pointed out that there may be a possibility 

 of reducing such a very important matter as the manure account. 

 In order to convince you that there may be a possibility of reduc- 

 ing that expenditure, I have quoted facts and figures which have 

 led me to think that there is such a possibility. I don't want to 

 interfere with the present manuring problem. We are not in a 

 position to do so, but we are in a position to realise that we must 

 have information on the matter, that our present system of 

 manuring is not necessarily accurate or the best or the right 

 thing to do. 



Mr. Harris : — I should like to mention in connection with 

 what Dr. Lehmann said about the matter of experimental plots, 

 that what he stated is perfectly correct and that the average for 

 the past 4 years show that the manured plots have yielded the 

 smallest crops. But it is rather interesting to notice that during 

 the last year of the experiment the no-manured plots show a 

 decided tendency to decrease ; which rather points to the fact that 

 they might have fed on manure previously received. 



Dr. Lehmann : — That is just what I have been wishing to 

 impress upon the meeting. Probably we have over-manured the 

 plots in the past. If we had done so, we must know it ; because, 

 of the manure that we put into the soil, although a certain propor- 

 tion of it remains there, a certain proportion is lost. The experi- 

 ments which I have made in regard to the after effects of poonac 

 on Ragi have conclusively indicated that there is very little 

 manurial effect of poonacs left in the soil after one year. Our 

 principal manures have been bone and poonac. Bone contains 

 a certain amount of nitrogen. Its principal constituent is 

 phosphoric acid. If we take as a basis the experience of other 

 countries, we may say that phosphoric acid will remain in the soil ; 

 but the nitrogen, which is the most expensive constituent, will 

 undoubtedly be lost sooner or later. If we have applied manures 

 which have given nitrogen for four years, then we have been 

 applying very much, too much of it. The nitrogen that is 

 applied in the poonacs will certainly not last longer than four 

 years. 



Mr. DANVERS : — The nitrogen in bone, will it not last longer ? 



Dr. Lehmann : — I might say that in the experiments I have just 

 told you about there was apparently no after effect either from the 



