198 CULTURE OF FARM CROPS. 



tain important constituents within a limited area, enables 

 the plant to provide itself more freely and rapidly with 

 others it may require. 



9. Messrs. Lawes and Gilbert, as the result of an elaborate 

 series of experiments upon the growth of barley, have 

 shown that '' the produce of barley obtained in rotation 

 (the usual four-course or Norfolk system turnips, barley, 

 clover, wheat), even when the turnips were both unmanured 

 and carted off, was considerably greater than when the crop 

 was grown annually in succession on the same land," so 

 that, as they remark, it may fairly be concluded that a 

 " characteristic effect of alternating the other crops with 

 the barley " is to leave more available nitrogen from some 

 source within reach of its roots than is the case when the 

 barley is grown in successive crops on the same land, or 

 when a number of turnip crops were likewise taken in suc- 

 cession off the land previously; and the conclusion they 

 arrive at is, that, like wheat, barley requires " a nitrogenous 

 condition of soil," and that full crops cannot be obtained 

 unless there be within the soil available supplies of nitrogen. 

 The bearing of those remarks upon the question of rota- 

 tion is important, and will at once be recognised by the 

 intelligent reader. 



1 0. Let us, then, now draw our attention to a review of 

 the modes in use for the cultivation of barley. We have 

 already referred to the preparation of the land. In a prac- 

 tical paper on the " Management of Barley " by Mr. H. W. 

 Keary, a prize essay published in the " Journal of the Royal 

 Agricultural Society," there are some very excellent remarks 

 on this point. And here the importance of attending to 

 this may at once be recognised, from the fact, so carefully 

 pointed out by Mr. Keary, that upon it depends most ma- 

 terially the quality even perhaps more than the quantity 

 of the crop. So that although, as a rule, what are called 

 " barley soils " produce the finest yield both iir quality and 

 quantity, still remarkable differences in these respects are 

 noticeable, and this arising from the different modes in 

 which the same kinds of barley are cultivated. Mr. Keary 



