118 The Eothamsted Barley Experiments. 



and the quantity of both grain and straw fell off con- 

 siderably during the later years. With barley there was 

 much more grain, rather less straw, but considerably more 

 total produce than with wheat. Nitrogenous manures alone 

 gave much more barley than mineral manures alone ; the 

 produce declined much less in the later years ; and, for 

 twenty years in succession, fair, though not full, crops were 

 obtained. Nitrogenous and mineral manures together gave, 

 for twenty years in succession on the same land, rather more 

 of both grain and straw than farmyard manure, considerably 

 more than the average barley crop of the country under 

 rotation, and an average weight per bushel of between 

 531b. and 541b. With the same amount of nitrogen and 

 the same mineral manure, applied for twenty years, in the 

 autumn for wheat and in the spring for barley, the barley 

 gave much more grain, more straw, and nearly one-third 

 more total produce than the wheat. Thus, then, with barley 

 as with wheat, mineral manures alone failed to enable the 

 plant to obtain sufficient nitrogen and carbon to yield even a 

 fair crop ; the greater effect of nitrogenous manures alone 

 showed that the soil, in its practically corn-exhausted con- 

 dition, was relatively richer in available mineral constituents 

 than in available nitrogen ; and the generally greater effect 

 by nitrogenous and mineral manures together than by farm- 

 yard manure which contained not only very much more 

 nitrogen, but a large amount of decomposing carbonaceous 

 organic matter, and probably more of every mineral con- 

 stituent than the crop showed that the nitrogen of the 

 farmyard manure was in a far less rapidly available con- 

 dition, and that its supply of carbon was at any rate 

 unessential. 



Though it is a mere truism to assert that the growing 

 plant must have within its reach a sufficiency of the mineral 

 constituents of which it is to be built up, yet the results 

 obtained with barley, as well as those with wheat, have 

 shown that, whilst it is essential that there be a liberal pro- 



