150 



The Rothamsted Grass Experiments. 



mineral matter during the second period as compared with 

 the first. Yet it is an established fact that nitrogenous 

 manures are specially effective in increasing the growth of 

 gramineous crops grown separately on arable land, such as 

 wheat, barley, or oats, though these only contain a com- 

 paratively small percentage of nitrogen, and assimilate a 

 comparatively small amount of it over a given area when 



TABLE XXXIII. AVERAGE PER ACRE PER ANNUM, BY MIXED 

 MINERAL MANURE ALONE ; PLOT 7. 



Average per Acre per Annum. 



none is supplied in manure. The highly nitrogenous 

 leguminous crops, on the other hand, such as beans, peas, 

 clover, &c., are not characteristically benefited by the use of 

 direct nitrogenous manures, though nitrates do act more 

 favourably on them than ammonia-salts. Again, whilst, 

 under equal conditions of soils and seasons, mineral manures 

 alone increase comparatively little the gramineous crops grown 



