30 ENGINEERING FOR LAND DRAINAGE. 



At Windsor, Conn. , light sandy tobacco soil contain- 

 ing 1 .3 per cent of clay averages 10 per cent of water 

 for the growing season. 



Heavy limestone, tobacco, corn, wheat, and grass 

 land at Litiz, Pa., containing 36 per cent of clay, carries 

 23 per cent of moisture. 



At Lexington, Ky., blue grass and tobacco soils 

 which maintain about 3$ per cent of clay, carry 22 per 

 cent of moisture. 



Results of experiments at Germantown, Ohio, on 

 cigar tobacco soil which is also good for corn, wheat 

 and grass, show 27I per cent of clay in the subsoil and 

 22 per cent of moisture. 



Further experiments only confirm the above and 

 indicate that our heavy soils suitable for grass and 

 grain contain from 20 to 36 per cent of clay and carry 

 from 20 to 23 per cent of moisture, while the light, 

 sandy truck soils have as low as 3 per cent of clay and 

 carry 8 per cent of moisture. 



Compare these results with the volume of empty 

 space in the several examples of soils, and we can de- 

 termine with approximate correctness the volume of 

 water that must be removed from a saturated soil be- 

 fore it becomes fitted for the several crops which it is 

 desired to grow* 



Effect of Fertilisers nfofi Soil Moisture. 



From some experiments made by the Department it 

 is shown that the addition of certain fertilizers placed in 

 the soil causes it to retain moisture with greater tenac- 

 ity. This is accounted for by supposing that the ac- 



