16 



NEW HAMPSHIRE EXPERIMENT STATION 



[Bulletin 271 



That timothy responded to lime on this soil is evidenced by the data 

 presented. The average annual gain for two tons of lime over no lime 

 was 619 pounds of hay per acre per year; for four tons of lime, 793 

 pounds of hay. As this soil was not nnu-h more acid than the average 

 for the state as a whole, the data iiulicate thai lime is often a factor 

 limiting yields, even on grass hay. 



Soil samples were taken from each ]il()f befoi'e the field was plowed 

 or any treatments applied, and amuudly in October during the course 

 of the experiment. The quinhydrone electrode was used in determin- 

 ing the pH of each sample. 



The pH value for each year corresponding to the average cH values 

 of all plots receiving similar treatments are presented in Figure 3. 



It is practically impossible to bring this soil to neutrality by the ad- 

 dition of ground limestone. Starting with an original pH of about 



General lay-out of plots. The heavily manured jilot at right 



shotvs slight lodging. 



5.4, the lowest average acidity caused l)y two tons of ground limestone 

 per acre was 5.97; by four tons per acre, 6.26 (Fig. 3, 1930). In in- 

 dividual plots, these average values for pll are exceeded somewhat, 

 but the highest figure recorded is 6.83. 



Plowing alone results in decidedly increased soil acidity the following 

 year (Fig. 3). This increase is prevented by the application of manure 

 (Fig. 4). The whole field was plowed shortly before the 1931 soil 

 samples were taken. This in itself would seem to be sufficient to ac- 

 count for the marked increase in acidity of all plots at this sampling. 

 Limestone and manure had been applied so many years before this 

 sampling that they were no longer able to prevent the increased acidity 

 due to plowing. By the second year the dififerences in acidity between 

 plowed and unplowed soils had practically disappeared (Fig. 3). 



The buffer effect of manure is shown on unlimed soils by the decidedly 

 greater acidity of those plots receiving no manure (Fig. 4). When 



