40 REPORT OF THE AGRICULTURAL RESEARCfi 



6. Drainage. — Records from all the four drain gauges 

 were maintained. In the monsoon of 1907, these differed 

 only markedly in the amount of surface drainage which 

 was greater from No. 1 than from the others. Never- 

 theless the No. 1 gauge probably yields the most reliable 

 data. Nos. 2 and 4 had grass on them and were expected 

 on this account to behave differently from Nos. 1 and 3. 

 The rainfall was sufficiently heavy on two occasions to 

 cause an overflow from the pipe fixed at a nominal 2" above 

 the ground level, and the amounts' that ran off were 0-5" 

 during a 4'' rainfall and 3-5" during a 7" rainfall. 

 The amount of water which percolated was 7-5". The 

 rainfall was 40-3" during the j^ear (October 1906 to 

 September 1907), and the amount which evaporated during 

 the twelve months was accordingly 28-8". These are the 

 quantities measured from No. 1 gauge. 



The data of the drain gauges at the Cawnpore farm 

 and the samples of the drainage water from them, are pro- 

 vided for this section by the courtesy of the Director of 

 Land Records and Agriculture, United Provinces. The 

 four years' data obtained from these gauges, show that the 

 evaporation there amounts to between 14" and 20" in 

 extreme cases, and that the average is approximately l7" 

 per annum. Hence the amount lost from the Pusa soil 

 is considerably greater than at Cawnpore. This result 

 is probably fully explained by the fact (referred to below) 

 that the Cawnpore soil contains less maximum water per 

 cubic foot than the Pusa soil. 



Regarding the constituents which are dissolved in the 

 drainage water, the total amount of nitrogen (as nitrate) 

 in the drainage water was 201b per acre from the bare 

 tallow soil and -04^ from that growing grass. This 

 year maize is being cultivated on gauges Nos. 2 and 4 

 m place of grass. The Cawnpore gauge soil which is 

 maintained fallow, continues to yield large amounts of 

 nitrate. This varies, however, a good deal with the rain- 

 fall and also with the depth of the gause. Over a series 

 of years these gauges are yielding approximately equal 



