12 



CIRCULAR XO. 127, BUREAU OF PLANT INDUSTRY. 



at planting time, an experiment with the two classes of seed was 

 conducted on 22 tenth-acre plats. The seed imported from Oregon 

 had been stored there in pits during the winter of 1911-12. Four 

 plats of this seed were planted, two on land plowed 6 inches deep 

 and two on 12-inch plowing. In the same series, nine plats plowed 

 6 inches deep and nine plats plowed 12 inches deep were planted to 

 locally grown seed. The results are given in Table VI. 



Table VI. — Results obtained with potatoes grown from Oregon seed and from locally 

 grown seed at the Delta Experiment Farm in 1912. 



Stand per cent. 



WUt do . . . 



Marketable yield per acre pounds . 



Unmarketable: 



Undersized per cent . 



Scabbv do. . . 



Oregon seed . 



Deep 

 plowed. 



39.1 



S3. 



10,204 



37.6 

 .5. 1 



Shallow 

 plowed. 



37.4 



81.0 



9,440 



1.5.6 



ti. 6 



Locally grown seed. 



Deep 

 plowed. 



31.0 



70.0 



6,445 



24.2 

 6.4 



Shallow 

 plowed. 



30.0 



74.0 



6,272 



20.5 



.5.7 



Table VI shows the differences in yield between pit-stored Oregon 

 seed, sound and unsprouted, shipjjed in at planting tune, and local 

 seed weakened by si)routing. The yield from Oregon seed was decid- 

 edly higher and the stand was better. It is also noticeable that deep 

 plowing again gave better results than shallow plowing. 



SUMMARY. 



The work conducted on potatoes at the Delta Expermient Farm in 

 1912 resulted in several important indications. Some of the more 

 prominent facts noted are the following: 



(1) Of the three commercial fertilizers used, superphosphate was 

 the only one which markedly increased the average yields as com- 

 pared with those obtained from the unfertilized plats. 



(2) Better average results were obtained from the use of commer- 

 cial fertilizers when the application was made in March than when the 

 fertilizer was applied at planting time, in June. 



(3) Plowing under a green-manure crop of barley resulted in in- 

 creased average yields. 



(4) The yields were generally better on 12-inch plowing than on 

 6-inch plowing. 



(5) No consistent yield differences were obtained where super- 

 phosphate was applied in varying quantities. The growth of haulm, 

 however, was increased by the heavier applications. 



(6) Acidulation of the irrigation water with sulphuric acid resulted 

 in no apj^reciable reduction in the action of potato scab and no in- 



ICir. 121] 



