20 



THE ROTHAMSTED EXPERIMENTS. 



Turnips 

 reverting. 



Common 

 practice 

 of root cul- 

 ture. 



Without 

 manure. 



With 

 dung. 



spreading laterally, the leaves and stem would be larger, 

 both actually and proportionally to the root, and the enlarged 

 root itself would serve as a store of material for the second 

 or final growth. 



To obtain the cultivated root, however, as grown as a rota- 

 tion and food crop, the conditions required are very different. 

 The seed is sown at a different period, and the character of 

 the manuring, and of the season of growth chosen, are in 

 their conjoint influence such as to favour a very abnormal 

 accumulation of the store-material in the root, and to secure 

 that this development shall attain a maximum within the 

 limits of the season. It will be seen, however, that the 

 cultivated turnip very soon reverts to its more natural 

 characteristics if the mode of treatment be not such as to 

 favour the artificial development. 



The first results to be adduced relate to experiments with 

 a variety of the common turnip, or Brassica rapa. 



1. Experiments with Norfolk White Turnips. 



Eoot-crops — whether common turnips, Swedish turnips, or 

 mangel-wurzel — are in ordinary practice grown by the aid 

 of large dressings of farmyard manure, with or without 

 artificial manures in addition. The farmyard manure is in 

 some cases applied for the preceding grain crop, but more 

 generally directly for the root-crop itself. The following 

 table shows the results obtained with Norfolk white turnips, 

 both without manure, and by 12 tons of farmyard manure 

 applied annually for three years in succession. 



TABLE 2. — Produce of Norfolk White Turnips. 



Thus, the produce of this assumed restorative crop, when 

 grown without manure, went down in the third year to 

 practically nothing — only 13f cwt. per acre ; whilst in the 

 third year with farmyard manure there was more than 

 17 tons. But the amount varied very much according to 



