1882.] COMMERCIAL FERTILIZERS. 155 



ence and study of his soil, might keep a practically accurate 

 credit and debit account with the land which would make 

 evident on the balance sheet what was needed in the line of 

 fertilizers. 



He would have to study the characters of his soil, its pro- 

 ducing-power without manure, for various crops. He would 

 have to consider the peculiarities of the crops which his cir- 

 cumstances would justify cultivating. He would perhaps 

 need more full and exact knowledge of the habits, and make- 

 up of tlie plants he grows, than can readily be found. He would 

 easily see that between clover and timothy, as between pota- 

 toes and corn, there are wide differences of structure. He 

 would ask for exact estimates of the comparative feeding 

 power of these plants. He would demand to know the mass, 

 the depth, the penetrating power of their roots, so that he 

 could judge between his crops as now he can compare his 

 animals in respect to their wants and their capacities. 



A crop that has a short period of growth, or that grows 

 very rapidly at some stage of its development, makes a dif- 

 ferent demand on the soil from one which has a long period 

 of slow and steady growth. The former may not remove 

 from the soil as much plant-food of any kind as the latter, but 

 it may require a richer soil and more abundant nourishment, 

 because it has the habit of rapid growth — it may demand 

 more plant-food in a given time. The clover crop is one which , on 

 soils favorable to it, requires no nitrogenous manures, but is able^ 

 to supply itself with nitrogen from the soil and atmosphci'e. 

 In many localities it is used as a manure for the wheat crop. 

 The clover is a steadily-growing biennial plant, with a massive 

 root-system which penetrates the soil deeply, and if cut or fed 

 off in blossom, comes on with a heavy aftermath, and besides 

 yielding a large amount of the best forage, leaves in the soil 

 two or three tons per acre of roots and stubble. When the 

 clover-ground is broken up and sown to winter wheat, the lat- 

 ter finds a rich manuring of clover roots which, the ensuing- 

 summer, fully sustains its rapid growth, while without such 

 preparation the wheat crop would be a comparative failure. 

 The diiferent kinds of plant-food have each a separate na- 



