176 THE PRINCIPLES OF 



of the grasses proper, leguminosse, and the miscellaneous 

 herbage is among the most remarkable results obtained. 

 It is, however, only within my power in the present volume 

 to draw attention to this interesting subject, and to recom- 

 mend the perusal of the Rothamsted experiments as exceed- 

 ingly instructive and of great practical importance. 



Lastly, with regard to the effect of fertilizers upon such 

 leguminous crops as beans, peas, vetches, and clovers, the 

 conclusion arrived at by Sir John Lawes is, that mineral 

 constituents applied as manure (particularly potash) con- 

 siderably increased the crops. Ammonia salts produced very 

 little effect, and in some cases have proved pernicious. 

 Nitrate of soda has, however, produced more marked results. 

 When we remember that a leguminous crop contains two, 

 three, or more times as much nitrogen as a cereal crop, it is 

 remarkable that nitrates and ammonia salts should exert 

 little or no effect. The explanation appears to be that they 

 derive their supplies of nitrogen from, the deeper layers of 

 the sub-soil, and partly from the air. 



The Rothamsted results are worthy of the closest study. 

 They are scattered throughout the long series of the Journals 

 of the Royal Agricultural Society. An excellent synopsis 

 of these experiments, so far as they relate to the growth of 

 wheat, barley, and the mixed herbage of grass land, from the 

 pen of Professor Fream (now being published at The Field 

 office), will be found exceedingly useful reading, not only 

 for students, but for every one who is interested in this most 

 important subject. 



The most notable addition to our sources of phosphoric 

 acid of late years is undoubtedly basic cinder. Basic cinder, 

 or Thomas phosphate powder, is destined to play a very im- 

 portant part as a fertilizer. I have a pamphlet before me in 

 which I am told that no less than 200,000 tons of this cinder 

 are produced in the iron works of Germany, and 130,000 



