CROPS AND SOIL IMPROVEMENT 



rectly from the manure applied three or four years 

 previously. Half of the field may thus be lifted 

 out of a helpless state and remain out of it for a 

 long term of years, while the other half grows 

 only poorer. A probable illustration of this last- 

 ing indirect effect may be seen in one of the plats 

 in the soil fertility experiments on the Pennsylvania 

 experiment station farm. 



Experiments at the Rothamstead station, Eng- 

 land, show some lasting results from applications 

 of manure. Director Hall cites the case of one 

 plat of grass land which was highly manured each 

 year from 1856 to 1863, and has since been left 

 unmanured. In 1864 this plat gave double the 

 yield of an adjoining plat which had been left 

 unmanured during the 8 years. In 1865 the plat, 

 last manured in 1863, gave over double the yield 

 of the unmanured. In the following 10 years its 

 yield was a half more than that of the unmanured. 

 In the next 10 years the yield was a quarter more. 

 In the next 10 years it fell to 6 per cent more 

 than the plat that had received no manure in the 

 beginning of the experiment. In the following 

 10 years it rose to 15 per cent. Here is a lasting 

 effect of manure for over 40 years where grass 

 was grown continuously. 



[148] 



