CH. X] 



Lasting Ejfect on Fertility 



18a 



On the mangold fields these physical effects on tilth 

 and moisture supply considerably help the young plant 

 in a dry season. (Fig. 36.) 



The effect of farmyard manure in building up fer- 

 tility of the soil is strikingly shown on one of the barley 

 plots at Rothamsted. This received farmyard manure 

 annually for 20 years from 1852 to 1871, but nothing 



60 



50 



e 40 



o 



e 



ID 



"^30 



I ( 



m 20 



10 







7-2 



7-1 



1-0 



1852-1861 1862-1871 1872-1881 1882-1891 1892-1901 1902-1911 



Fig. 37. Yield of barley in successive ten year periods, 1852-1911. 

 Plot 1-0. Unmanured Plot. Plot 7-2. Farmyard Manure. 



Plot 7-1. Farmyard Manure 1852-71; unmanured 1872-1911. 



since. Alongside is a plot that has received nothing 

 during the whole period. The effect of the farmyard 

 manure went on increasing during the first 13 years; it 

 then increased no more, but kept at its high level. In 

 1872 the farmyard manure was discontinued. The yield 

 has gradually fallen, but even after 46 years it is still 

 well above the level of the unmanured plot (Fig. 37). 



