108 OF FERTILIZERS. 



a smelling bottle, knows the effect of ammonia upon the 

 organs of smell. 



When the manure is immediately covered up, the 

 ammonia, as it is disengaged, is kept in the soil, espe 

 cially if there be clay or loam or something else present 

 which has an attraction for it. 



361. Organic Manures are divided into Vegetable Ma 

 nures, Animal ^lanures, and Mixtures of Vegetable and 

 Animal. 



The principal vegetable manures are green crops, kelp 

 and rock-weeds, straw, sedge or reeds, leaves, brewer s 

 grains, &c. 



362. Green Manures are standing crops, ploughed in, 

 if possible, when ripe, for it is then that they contain the 

 greatest quantity of soluble matter. The best plants for 

 the purpose are the different kinds of clover, lucerne and 

 sainfoin, vetches, buckwheat, cabbage-leaves, radishes, 

 turnip-tops, wild mustard and wild turnip, potato-tops, 

 Indian corn, rye, &amp;lt;fcc. Yet some of these are better 

 suited to certain soils than others. 



To be suited to this purpose, plants should grow rap 

 idly, so as not to occupy the land too long ; their seed 

 should be cheap,, and they should be plants which borrow 

 most of their elements from the atmosphere. Such plants 

 bestow upon the soil more than they receive from it. 



363. The green crops best suited to. light and sandy 

 soils are buckwheat, the clovers, cabbages, radishes, wild 

 mustard, potato and turnip-tops, rye, and Indian corn. 

 For stiff, clayey soils, beans and pease, the different kinds 

 of clover, vetches, &c. But green crops are less suited to 

 clayey than to any other kind of soil. For calcareous 

 soils they arc exceedingly advantageous, as such soils 



