36 Irrigation and Drainage 



No. of cylinders 13 14 23 24 



Dry matter produced Ibs 4 3.16 4.93 4.32 



Total water used Ibs 1,808 1,668 2,061.5 1,782.5 



Dividing the amount of water used on the four cylinders by 

 the dry matter produced, we get, as the mean of the four trials, 

 under the conditions of the plant-house, 446.1 pounds of water for 

 a pound of dry matter, and a yield of dry matter per acre amount- 

 ing to 12.645 tons, which is very large, indeed. The water used 

 by this crop expressed as rainfall was, as a mean of the four 

 trials, 49.76 inches. Here is a depth of water used from this soil 

 which is a little greater than the soil itself ; but the rate at which 

 the water was used, it will be observed, is less per pound of dry 

 matter produced than that for the out-of-door experiments. 



In the case of the clover on these black marsh soils, there 

 were eight of the large cylinders used, in four of which medium 

 clover grew, and on the other four alsike clover. These were 

 sown without a nurse crop, and at the same time as the oats, but 

 were cut July 8, so that the period of growth was 207 days. The 

 results obtained here with medium clover were as stated below : 



No. of cylinders 15 16 21 22 



Dry matter produced gms 507 608 620 573 



Water used Ibs. 673.5 795.5 819 678 



Dividing the total amount of water used on the four cylinders 

 by the total dry matter produced, we get 582.9 pounds of water 

 as the amount used per pound of dry matter. In this case the 

 yield of dry matter per acre was 3.92 tons, equal to 4.61 tons 

 of hay containing 15 per cent of water. The amount of water 

 used, expressed in inches, was 20.16. 



The alsike clover gave yields and results as follows: 



No. of cylinders 17 18 19 20 



Dry matter produced-gms 628 616 576 634 



Water used Ibs 809 758 774 804.5 



In this case, the mean amount of water for a pound of dry 

 matter was 581.5 pounds, and the yield of dry matter per acre 



