5 



" the plants did fully as well as in Jthe other systems and with less 

 water." 



Where irrigating is to be done on a large scale, it seams to be the 

 concensus of opinion that surface irrigation by means of furrows is 

 undoubtedly the most practical method. In greenhouses and gardens 

 subirrigation by means of tiles may often be found advisable. Further- 

 more, many soils need drainage and require the laying of tile. On 

 such soil it may be possible to combine drainage and subirrigation 

 economically, and the Wisconsin Experiment Station is at present 

 studying this subject. 



A question of the greatest importance in regions of deficient rainfall 

 or where irrigation is practise! is the storage capacity of the soil for 

 water. When the soil is thoroughly loosened up, the amount of water 

 which it will hold jis greatly increased, and the rise of water to the 

 surface and evaporation are checked. Experiments at the Wisconsin 

 and Nebraska Experiment stations have shown the beneficial effects :'n 

 these respects of subsoiling. On this point the Nebraska station makes 

 the following suggestions : 



Subsoil ploughing, although a means of conserving moisture, does not produce 

 it, and is, therefore, not a substitute for irrigation where the rainfall is too s nail 

 to produce crops. 



Where there is a hard, dry subsoil, subsoil ploughing is to be recommended. 



Where the subsoil is loose, gravelly, or sandy, subsoiling is probably unneces- 

 sary, or may even be injurious. 



Do not subsoil when the soil is very wet, either above or beneath, as there is 

 great danger of puddling the soil, thus leaving it in worse condition thai before. 

 This is one of the reasons why it is better to subsoil in tha fall thai in the spring. 



If the ground be subsoiled in the fall, the winter an 1 spring rains have ample 

 opportunity to soak in, that being the season of greatest rainfall and least evapo- 

 ration. 



Subsoiling in the spring maybe a positive detriment if the subsoil be extremely 

 dry, as in that case the rain water is partially removed from the young plant by 

 the absorption of the bottom soil. If the spring rain3 were heavy, this would not 

 be a disadvantage. 



It is probable that the increased yields on subsoiled lands are mainly, 

 if not entirely due to the increased amount of water which such land 

 is able to store up for the use of the crop. Subsoil ploughiag nuy thus 

 be made the means of greatly extending the area over which crops may 

 be successfully grown without irrigation, and when practised in con- 

 nection with irrigation may result in a great saving of irrigation water. 

 As indicated above, however, before deciding upon the advisability of 

 subsoiling it is necessary to ascertain, among other things, the nature 

 and condition of the soil and subsoil. (U. S. Dept. of Agri., Farmers 

 Bulletin No. 56 ) 



Irrigation in India. 

 For many years it has been well known in India that irrigation 

 should not be allowed in places where the soil is much impregnated 

 with salts or where the subsoil drainage is defective. So long ago as 

 1862, General Strachey of the Royal Eagineers, lucidly stated the case 

 as follows : — 



The salts known as " reh" are contained in the soil. If cinal per- 

 colation takes place, it may at length proceed to such an extent as to 

 saturate the subsoil with water. The surface being at the same time 

 .exposed to sun and air, becomes heated, and continual evaporation goes 



