370 DRY FARMING 



followed by selection. It is true generally that "like pro- 

 duces like", 'but it is not always so. Variations occur in 

 all our crops. It is necessary then that the undesirable 

 variants be eliminated and that the favorable ones be 

 isolated and tested out, and if better than the parent, 

 increased and made available to the crop grower. This 

 is accomplished by the selection of individual plants, the 

 propagation of the seed in a "pure culture", the testing 

 of its yield and constancy for a number of years, and 

 then increasing it as quickly as possible and making it 

 available to the crop grower. 



"Crossing" is resorted to, first, in order to produce 

 variation so as to give greater opportunity for selection, 

 and second, to engraft on a race some desirable charac- 

 ter possessed by another. Crossing or breeding, the in- 

 termixture of the blood of two parents results in many 

 new combinations of characters, some one of which may 

 be the very one desired by the breeder. This favorable 

 plant must be found, isolated, tested out, the seed in- 

 creased, and then distributed. Practically all of the 

 common crops now grown have felt the influence of the 

 breeders' touch. Marquis wheat, Victory oats, O.A.C. 

 No. 21 barley and N.D. No. 959 winter rye are familiar 

 examples of improvement by selection and breeding. 



332. Irrigation and Drainage. In warm, dry climates, 

 moisture is the limiting factor in crop production. Where 

 water can be secured by artificial means, a profitable 

 agriculture generally results. We practise irrigation in 

 parts of Western of Canada, but over most of our coun- 

 try, it is not possible to do so, because water is not avail- 

 able. 



In wet climates and low lying soils moisture may also 

 limit the yield, not because there is too little, but because 



