1048 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



to incorporate with both soil and subsoil a quantity of either basic slag 

 or bone meal as large as would be used collectively in several years* 

 ordinary annual dressings. Where, however, there is sufficient lime in 

 the soil, an annual dressing of superphosphate is probably all that need 

 be used. 



In Asparagus culture, as in the case of all other crops, the market 

 grower will probably like to vary the nature of his artificial or concen- 

 trated fertilisers from time to time ; on which question, however, the 

 reader is referred back to our introductory remarks on an earlier page. 



Leguminous Crops. 



The great discovery of the power of leguminous plants to assimilate 

 free nitrogen from the air through the medium of the micro-organisms 

 inhabiting the tubercular nodules found on their roots, has led a great 

 many teachers of agricultural chemistry to assume that the supply of 

 nitrogen thus naturally obtainable is necessarily sufficient to enable such 

 plants to dispense altogether with the aid of nitrogenous manure. In 

 some cases — as, for instance, when a crop like Red Clover is grown in the 

 course of an ordinary four- crop rotation — such a view is no doubt well 

 grounded. Not, however, because Clover neglects to avail itself of 

 manurial nitrogen existing in the soil. Indeed, it has been abundantly 

 proved by the Rothamsted investigations that Red Clover, as well as other 

 kinds of Clover, feeds abundantly upon nitrogen in the form of nitrates. 

 The residues, however, of the dung and other nitrogenous manures applied 

 to other crops in the rotation are probably generally sufficient, together 

 with what the crop absorbs for itself from the air, to enable it to grow to 

 perfection. 



No doubt the degree to which leguminous crops are benefited by or 

 indifferent to direct applications of manurial nitrogen depends to a con- 

 siderable extent upon whether the micro-organisms necessary for the 

 tubercular formation and for free nitrogen assimilation are present in the 

 soil in sufficient abundance, and upon whether the circumstances are 

 such as to encourage their free development. 



It having come to our knowledge some years since that both in 

 Spain and in America nitrate of soda had been freely and profitably 

 used in the cultivation of Lucerne, or 4 Alfalfa,' we had the curiosity to 

 lay down four plots of land with Lucerne by the side of our market- 

 garden crops, manuring them with mineral manures with and without the 

 addition of nitrate of soda. The results of our six years' experience with 

 these plots are given in the following table. Practically they corroborate, 

 as regards the efficiency of nitrogenous manuring, the results of the 

 Lucerne experiments carried out by Dr. Voelcker on smaller plots at 

 Woburn, and show very clearly that Lucerne is capable of responding 

 freely to the application of nitrogenous manure. It will be seen that, 

 on the average of six seasons, the addition of 2 cwt. of nitrate of soda 

 per acre to the phosphates and potash has produced an extra yield 

 amounting to 4 J tons of green Lucerne per acre over and above that 

 given by the phosphates and potash salts alone. 



