116 RESULTS WITH TURNIPS 



nitrates provided by the soil for the turnip crop thus especially 

 large, the turnip crop is also exceptionally capable of turning 

 this supply to good account. The period of growth of 

 the crop is a long one, and continued far into the autumn ; 

 the crop is thus able to make full use of the nitrogenous 

 food furnished by the soil. As a consequence of these 

 facts, the turnip crop is not one benefited by large applica- 

 tions of nitrogenous manures. On land in good agricultural 

 condition, and well tilled, very fair crops of turnips may 

 frequently be obtained without the use of any nitrogenous 

 manure ; and on such soils only small quantities of ammonia 

 salts could be applied with any profitable return. To apply 

 more manure than a crop can turn to account during its period 

 of growth is seldom economical, and is certainly never econom- 

 ical in the case of active soluble manures such as sulphate of 

 ammonia. Any liberal use of ammoniacal manure for the 

 turnip crop must thus be reserved for the special case of soils 

 poor in nitriftable matter. 



While the turnip crop occupies such a strong position in 

 regard to its supply of nitrogen, it is, on the other hand, of all 

 farm crops the one least able to supply itself with phosphates. 

 Phosphatic manures have thus for the turnip crop a special 

 value and importance. 



A full crop of turnips demands a large quantity of potash. 

 The crop has, however, frequently little difficulty in obtaining 

 what it needs from the soil. Potash manures are thus not, like 

 phosphates, generally essential for successful turnip culture ; 

 their use is especially profitable when farmyard manure is 

 not employed, or when very large crops have to be grown. 



i. Experiments at Rothamsted. The field experi- 

 ments on the turnip crop commenced in 1843 with Norfolk 

 White Turnips. Trials with ammonia salts were made from 

 the first, but during the early years the manuring of the plots 

 was of a miscellaneous character, and little suited to illustrate 

 the return which ammoniacal manures will yield when used 

 to the best advantage. In 1845 a part of all the plots re- 

 ceived a cross dressing of 3 cwts. of sulphate of ammonia. 

 Excepting in the case of a few plots which had received 



