296 



EXPERIMENT STATION RECORD. 



Changes in the tvater content of soil irrigated through tile drains. 



Above two lines of tile 



Eight feet from the two lines of tile.. 

 Sixteen feet from the two lines of tile 



! Second 

 Surface I foot 

 foot lost, gained ( + ) 

 or lost ( — ). 



Per cent. Per cent. 



2.1 +1.4 



0. C I +1.3 



1.6 ! —0.5 



Third 



foot 

 gained. 



Per cent. 

 3.4 

 4.1 

 3.5 



Fourth 



foot 

 gained. 



Per cent. 

 2.4 

 3.1 

 0.3 



A similar experiment was made with the straiglit line of tile 755 ft. 

 long, running from the silt well of the main system to the outlet. "The 

 experiment served to demonstrate that under certain conditions it 

 would be x^ossible to comi)letely saturate a tile-drained field by pump- 

 ing water through the main, allowing it to set back into the laterals 

 and rise by hydrostatic pressure and capillarity to the surface.'' 



These preliminary experiments conducted in 1893 were repeated in 

 1895 with a larger pump, which raised the water into a distributing 

 reservoir, from which it was conveyed through a 5-inch sewer pipe to 

 the drainage system. It was thus possible to measure with some deti- 

 niteness the quantity of water used. After 2 iireliminary experiments, 

 more exact observations were made on the rate of percolation. This 

 was found to be about 5 gal. per minute for each 100 ft. of tile for the 

 whole system. To saturate the 5 acres it was necessary to i)ump into 

 the drains 105,272 cubic feet of water, or enough to cover the area 5.8 

 in. deep. 



In an experiment with irrigation tile laid at a depth of 18 in. in sandy 

 reddish clay soil underlaid by coarse sand and gravel, the rate of per- 

 colation was 5.98 gal. per minute for 100 ft. of tile, the water being 

 under considerable pressure. 



In connection with this experiment the influence of surface irrigation 

 and subirrigation on the growth of corn was also noted. The results 

 are summarized in the following table: 



Infiuence of irrigation on the growth of corn. 



Not irrigated 



Surface irrigated 

 Subirrigated 



Amounts of water. 



In rain. Applied. Total 



Inches. 

 8.15 

 8.15 

 8.15 



Inches. 



8.61 

 13.72 



Inches. 

 8.15 

 16.76 

 21.72 



Yields per acre. 



Flint 

 corn. 



Pounds. 

 7,916 

 11,080 

 9,545 



Dent 

 corn. 



Pounds. 

 7.426 

 9,625 

 7,907 



"One object of these experiments was to learn how much closer than the general 

 practice of field planting corn may be grown provided ample water is furnished, 

 and the results appear to warrant the conclusion that with more water supplied and 

 less wasted a considerably closer stand and much larger yield may be had." 



In these experiments, however, the unirrigated thick-seeded corn pro- 

 duced no ears, while the irrigated thick-seeded corn yielded as a rule 

 small immature ears. 



