EFFECT OF FEEDING EOOTS ON THE LAND 207 



the yield of barley is increased by as much as 53 per cent, 

 through the return of the root crop to the land. The residues 

 have, however, but a small effect two years later on the wheat 

 crop which follows the bare fallow, for where the roots were 

 fed the wheat crop is only 13 per cent, larger than where 

 the roots were carted off. The residual effect has practically 

 disappeared by the fourth year, and when the roots (to which 

 a fresh application of manure is applied) come round again 

 they are little the better for any accumulated residues in the 

 soil, even though the treatment of returning or removing the 

 roots is repeated through thirteen rotations, or a period of 

 fifty-two years. 



The next Table (LXXII.) shows the parallel experiment, 

 in which clover or beans were grown in the third year of the 

 course instead of taking a bare fallow. 



TABLE LXXII. Effect of Carting and of Feeding Hoots on the Yield 

 of succeeding Crops. Clover grown. 



In this case the effect of feeding the roots on the land is 

 plainly visible in the following crop, though the increase is not 

 so great (being 28 per cent, instead of 53 per cent.) as when the 

 rotation includes a bare fallow. 



The second crop, clover or beans, is also benefited to some 

 extent, for the residue of the roots produces a mean increase of 

 9 per cent. Now, however, the new stores of nitrogen intro- 

 duced by the clover crop practically obliterate all further effect 

 of the residues, and the wheat crop is to only a trifling extent 

 the better for the return of the Swedes to the land three years 

 previously. 



