24 REPORT" OF THE AGRICULTURAL RESEARCH 



No. 8, Chemical Series, and dealt with both the total amount 

 transpired as also the period during which the greater 

 part was assimilated. The effects of temperature and 

 humidity, proportion of water in the soil, manure, the 

 nature of the crop, etc., were dealt with. One of the most 

 important of these is manure, which whilst increasing the 

 weight of the crop and consequently the amount of water 

 required, effects an economy of the latter since the increased 

 requirement of water is proportionately less than 

 the increase in crop. Good tillage probably has a similar 

 property. The second section of the investigation has to 

 do (^) with the effect of different soils and (ii) with the 

 results of field tests; this will be published shortly. 



Soil Gases. — ^The first section of work in connection 

 with the subject of soil gases dealing with the relations of 

 carbonic acid to calcium carbonate and water, has been 

 published as Memoir No. 7, Chemical Series, and it is 

 expected that a second section dealing with the similar 

 relations to magnesium carbonate will be published in the 

 course of the cold weather. 



Usar land. — At the request of the Deputy Director of 

 Agriculture, Central Circle, United Provinces, an investi- 

 gation into the nature of some land which has been going 

 out of cultivation in the Mainpuri District, has been com- 

 menced and has indeed absorbed so much time that no less 

 than three or four of the assistants are at present utilised 

 for it. 



The soil is Usar, of the " black alkali " type, but the 

 amount of alkali present was thought at first to be too 

 small to account for the sterility. The sub-soil water 

 level has risen seriously of late years and no doubt was 

 felt that this was one of the primary causes of the trouble. 

 But in addition to this, preliminary tests showed that the 

 soil is so highly impervious to water that this feature alone 

 might account for sterility. All, or at least nearly all, 

 the water assimilated by plants must move through a certain 

 amount of soil before it comes in contact with the root; 

 such distances may only be a few inches or centimetres, 



