14 



SCIENTIFIC AGRICULTURE 



September, 1921 



TaUe 3. 

 Dusts of Different Copper Content. 



From the above data it is evident t]iat 

 dusts containing copper and arsenic are 

 effective in controlling biting insects and 

 black spot under the conditions existing 

 in Nova Scotia. Some commercial Bor- 

 deaux powders are possibly as effective 



as the copper-arsenic dust here described, 

 but it is almost certain that comtoercial 

 Bordeaux mixtures can never be as cheap- 

 ly made. The writers have probably done 

 more work on potatoes with these dusts 

 than on .the apple, but it is considered 

 advisable to reserve this phase of t^e 

 question for a future paper. In the last 

 paper the question of relative costs was 

 briefly discussed. It was shown that 

 sulphur-lead arsenate dust was a trifle 

 more expensive than .spray, that spray 

 Avas somewhat more expensive than the 

 copper-arsenic dust, and at tihe same time 

 it was shown that apart from the matter 

 of relative costs, dusting possessed certain 

 definite advantages over spraying in the 

 control of biting insects and fungous dis- 

 eases. It would seem apparent therefore 

 that the copper-arsenic dust described or 

 some other dust containing copper and 

 arsenic which may in the future come to 

 light, should play an important part in 

 plant pest suppression. 



The Technique of Field Husbandry 

 Experimentation 



By MANLEY CHAMPLIN 



Professor of Field Husbandry, University 



of Saskatchewan. 



(An address before the Western Canadian Society of Agronomy at Edmonton.) 



Objects in View. 



In planning a set of experiments our 

 first care must always be to determine what 

 the problems may be that confront the 

 people whom we serve. A certain class of 

 problems may be Avorked out very satis- 

 factorily on an experimental station. An- 

 other class cannot be worked out to a sat- 

 isfactory conclusion on the experiment sta- 

 tion and must be solved, if solved at all. 

 by cooperative work with farmers. 



The primary objects of field husbandry 

 experimentation consist first in finding 

 out the best way to produce farm crops, 

 and second to introduce or breed new 

 varieties that Avill be better adapted to local 

 conditions than tliose already existing. 

 Such experiments as are designed to learn 

 the best dates of seeding, the most profit- 

 able rotation of crops, the best tillage me- 



thods and the most satisfactory methods of 

 replenishing the soil can be worked out to 

 best advantage by the use of a series of 

 carefully planned plot experiments. Plant 

 breeding or crop improvement work re- 

 quires the use of a smaller unit such as a 

 sliort row. Such experiments may be 

 known as nursery woi-k. After tlie best of 

 the ncAv or baby strains grow up they are 

 transferred to the field plots. Experi- 

 ments such as the reseeding of Avorn out 

 range lands, seeding AA-et land to grass mix- 

 tures, the determination of the value of 

 ncAv A'arieties in different localities and 

 many anotlier are best ada]itod to coopera- 

 tive ex]ierimental Avork Avitli farmers. With- 

 out an]/ one of tliesc tliree classes of ex- 

 perimentation we Avill fall short of our full 

 accomplishment and Avill not see fully 

 realized our great desire to do some good 

 "in the land Avhicli the Lord our God 



