INSTITUTE AND COLLEGE, PUSA, FOR 1911-12. 81 



moisture produces nitrogen starvation of the wheat crop; 

 the importance of biological analysis of irrigated soils by 

 such methods will readily be realized. 



A special enquiry has been carried on and is still pro- 

 ceeding, to determine the conditions under which bacterio- 

 toxins are formed in soils and their effect in inhibiting 

 bacterial action. The work of Greig Smith of N. S. Wales 

 on this subject has demonstrated its importance, and ex- 

 periments at Pusa have fully confirmed his views. Mr. 

 Meggitt, Agricultural Chemist, Eastern Bengal and Assam, 

 with whom I hope to collaborate on this subject, has carried 

 out a series of investigations on similar lines, but the en- 

 quiry is not sufficiently complete for detailed report. 



A complete series of experiments on green manuring 

 was designed and commenced, in collaboration with the 

 Imperial iigriculturist. This included observations in the 

 field and in the laboratory as to the effect of varying treat- 

 ment of the green crop (Crotalaria juncea) upon the condi- 

 tion of the soil and upon the succeeding crop. Field varia- 

 tions included burying after varying periods of growth, 

 at different depths, and in conjunction with various arti- 

 ficial manures. Laboratory experiments were carried out 

 to determine the rate and kind of change of the buried 

 organic material under various conditions, with special 

 reference to the formation of nitrate, and in order to obtain 

 data which might help to elucidate the problems connected 

 with the occasional failure of green manuring to improve 

 soil conditions. 



This enquiry will continue over two more seasons. 



4. Plant Pathology. — A bacterial disease of tobacco at 

 Rangpur was investigated and found to be due to an infec- 

 tion of B. Solanacearum. The strain isolated was found 

 to be also pathogenic to Solamim Melongena, Tomato, 

 Datura and Potato. The incidence of the disease at Rang- 

 pur and Burirhat was not apparently associated with any 

 insect attack or specially unfavourable soil conditions, and 

 was not heavy enough to cause apprehension as to future 

 spread. The parasitism of the causative organism as 



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