INSTITUTE AND COLLEGE, PUSA, FOR 1910-11. 29 



ments over several years have shown that practically the 

 whole of the water assimilated by a crop is obtained within 

 the root range, some 6 to 7 ft. in alluvial soil, and that al- 

 though the stores of water present below this depth are 

 very great, they are substantially of no service to the plant. 

 The field experiments were at the same time utilised to 

 check the values of the Transpiration Ratios which had 

 been found by pot-culture methods. The two methods 

 yielded very similar values for this factor. 



The investigation into the availability of flant food in 

 soils is being continued, but many difficulties have been met 

 with, and its progress is slow. 



TJsar Land. — Reference was made to this subject in the 

 last report, and the work has been extended. The first in- 

 vestigation had to do with a certain stretch of land in the 

 Mainpuri District, and a very exhaustive series of tests 

 showed that this class of usar land not only contains sodium 

 carbonate, but is also highly impervious to water. The 

 amount of movement of water, whether in the downward 

 direction during wet weather, or towards the surface dur- 

 ing the dry period, is thus necessarily only small; conse- 

 quently also there cannot be any large amount of movement 

 of salts. 



Experiments made at Pusa on this soil have shown that 

 by the application of common salt its physical state can be 

 altered and the salts washed out. Rice was grown on 

 some of it last year and is now growing again, but the 

 method is, I fear, not financially feasible. In other ex- 

 periments also made by pot-culture at Pusa, the physical 

 defect (imperviousness) was separated from the chemical 

 defect (alkali salts) and then plants sown. It was then 

 found that of the two the alkali was the more pernicious. 



During the past cold weather the investigation has been 

 continued in another direction in collaboration with the 

 Irrigation Department. One of the features of this alkali 

 land is frequently the occurrence of " alkali spots " in the 

 middle of fields otherwise quite fertile. It has been fre- 

 quently argued that these result from the presence of 



