INSTITUTE AND COLLEGE, PISA, FOB 1912-13. bP 



yield from the green manured plots, and in many there was 

 a decided falling off. There can be no doubt that this result 

 was due to the failure of the generally expected rainfall in 

 September and October (locally known as the " Hathia ") 

 as it was found on examination that the buried stems of 

 the green manure had failed to undergo complete decom- 

 position. 



Laboratory experiments showed that the nitrate formed 

 from the buried plant tissues increased in amount up to the 

 end of eight weeks from the time of turning into the soil, 

 provided the water supply was kept up to at least 16 per 

 cent, of the soil weight, but after this period a steady dimi- 

 nution took place, so that after twelve weeks a smaller quan- 

 tity of nitrate than that present at the end of the eighth 

 week was invariably found. The cause of this loss was not 

 discovered, although it may be conjectured that it was due 

 to the demands of the soil organisms for nitrogen, but its 

 invariable occurrence is interesting as helping to explain 

 the already well-known fact in held practice that too long an 

 interval between the burial of a green manure and the 

 sowing of the succeeding " rabi " crop is prejudicial to the 

 latter so far as any improvement which may be expected 

 from the use of the former is concerned. 



The results of the first year's experiments on green 

 manuring will be published in the form of a Bulletin. 



Further work on the occurrence of bacterio-toxins in 

 soil, their relation to infertility, and the action of tillage, 

 drainage, and manurial application in neutralizing them, 

 was carried out. 



Biological analyses of various soils were made and 

 further modifications of the method introduced; this sub- 

 ject, is still in a very early stage of development, especially 

 so far as interpretation of results is concerned, but it is 

 hoped that further experience and modification of the 

 method will lead to its successful application to the solu- 

 tion of various soil problems. At present it is possible 

 to determine the optimum moisture content of a soil for 



