12 N. H. Agri. Experiment Station [Bui. 296 



The only significant difference in the yields of the oats plots was for 

 the series on which double strength fertilizer was applied for the potato 

 crop. It is doubtful whether much importance should be attached to 

 this result unless it holds true over a period of years. 



Potatoes in a Three-Year Rotation. This experiment at the Jackson 

 Farm in Colebrook is similar to the Lane farm test with all the fer- 

 tilizer being applied to potatoes in a three-year rotation of potatoes, 

 oats and hay. It has not been possible to secure a stand of pure clover 

 on this soil and a mixture of clover and timothy is used. Excellent 

 yields of potatoes were secured in 1936. On the check series, to which 

 one ton of 4-8-7 fertilizer was applied, yields were 461 bushels per acre. 

 The efficiency of high phosphorus on potato production was borne out 

 by yields in the 4-16-14 and 4-16-7 series, which were 555 and 501 

 bushels respectively. 



It is quite apparent that lime has no effect on potato yields in this 

 experiment. Lime in the 4-8-0 series has consistently reduced potato 

 yields over the plots wiiich received no potash without lime due to the 

 depressing effects of lime on potash availability. 



The series receiving a mixed fertilizer with basic slag as the phos- 

 phorus carrier gave a significant increase, but the application of mag- 

 nesium on the plots had veiy little effect on yields in 1936. 



In the oats plots it is apparent that lime and residual phosphorus 

 have had a significant effect on oats yields. Basic slag fertilizer also 

 produced a significant increase, due probably to the fact that this ma- 

 terial holds its availabilitj^ over a longer period than superphosphate. 



The lime variables on this experiment all gave significant increases 

 in the hay crop. This will illustrate something as to soil acidity and 

 makes the lack of lime response in the potatoes all the more remarkable. 



Potato Scab Control. Tests on the limed plots in the potato rota- 

 tion, legume and dairy potato rotation experiments show that some 

 degree of control of scab may be obtained by the use of acidulating 

 materials. On soils with a medium pH ratio scab seems to be associ- 

 ated with recent applications of lime, however small, which may leave 

 spots of neutral or almost neutral areas within the soil mass. Soils 

 with a pH of over 5.0 showed considerabh^ more scab after recent ap- 

 plications of lime than those with a lower pH. As an acidulating ma- 

 terial aluminum sulphate showed a slight superiority over sulphur. 



Drilled Versus Broadcasting Fertilizer for Potatoes. A series of tests 

 at the Whenal Farm in Greenland to determine the relative merits of 

 drilling and broadcasting fertilizer for potatoes showed an increase of 

 25 bushels per acre in favor of the drilling placement. 



A Fertilizer Experiment with Dairy Farm Crops in the Connecticut 

 Valley. The results of seven years' experiments on the Livingston 

 farm near Claremont are outlined in detail in Station Circular 50, pub- 

 lished this year. 



The entire field embracing 80 twentieth-acre plots was plowed and 

 planted to Canada Leaming corn in 1936. The fertilizer schedule was 

 not changed for the various series except that no fresh lime was applied. 

 Manure was spread as a basic application on all plots. 



