62 SCIENTIFIC REPORTS OF THE AGRICULTURAL RESEARCH 



by a profound alteration in the physical texture of the soil. 

 When the land dries after a long period of surface water- 

 logging, it is difficult to obtain the ideal crumb structure 

 and to provide sufficient room in the soil for root develop- 

 ment. The clods do not readily break down under the 

 beam and the soil is gummy to the feel. Colloidal sub- 

 stances appear to be formed under these anaerobic condi- 

 tions which not only hinder the formation of a good tilth 

 but also prevent percolation. It is quite common at Pusa 

 after a very heavy monsoon to find the pore-spaces near the 

 surface almost entirely filled with water for some consider- 

 able time after the level of the rivers and of the ground 

 water has begun to fall. The surface soil does not seem 

 to be able to drain. An improvement in the texture fol- 

 lows if the surface drainage is improved and in cases where 

 organic matter has recently been added to the soil. The 

 gummy substances do not then seem to be formed to any 

 great extent and the clods readily break down. These 

 matters require exact and careful investigation and it is 

 difficult to suggest a more promising field of work for the 

 soil physicist in India. 



The effect of the rise of the subsoil water in preventing 

 drainage is well marked in North Bihar after the monsoon 

 has set in. The flow of the local rivers is soon checked by 

 the rise of the level of the Ganges. As a result, the 

 rivers overflow and the low-lying areas go under water. 

 The rise in the level of the rivers is followed by a rise in 

 the water-level of the wells. These movements of the 

 river-level and of the general ground-water are illustrated 

 in the curves opposite (Plate VI) which represent the condi- 

 tion of the river at Pusa and of one of the wells (about a 

 quarter of a mile distant from the river bank) for the 

 years 1910, 1912, 1913 and 1914. It will be seen that the 

 curves of the ground- water level vary according to the year. 

 In some years like 1912 and 1914, the curve is even and no 

 great oscillations of level occur. In others, such as 1910 

 and 1913, there are well-marked oscillations. These oscil- 

 lations, from the plant's point of view, are of the greatest 



