PRACTICAL HINTS ON FARMING. 39 



the miner. Mr, Boyle informs us that exhausted ores of tin 

 and iron, being exposed to the air, become again impregnated 

 with their respective metals. The air is no distinct element, 

 but a mass of heterogeneous things, very much etherialized. 

 Therefore, a well-hoed crop derives the advantage of contact 

 with this wonderful medium and rich storehouse of nature ; 

 and a top-dressing of plaster of Paris draws in the same 

 manner a supply of ammonia more reliable than the promises 

 of many of the patent fertilizers sold by travelling agents. 



The old English practice of laying lauds to fallow was 

 intended to get the fertilizing effect of the atmosphere. But 

 the present English practice of a rotation of crops is far more 

 speedy and profitable, by which the fertilizing qualities of 

 the soil may be distributed by cultivating, in rotation, crops 

 which respectively absorb different ingredients. Indian corn 

 and wheat draw largely on phosphates ; turnips and beets 

 on potash and soda ; and after these crops there will still 

 be enough of lime, etc., to produce a good crop of hay, and 

 this result, too, from one application of manure. The laud, 

 by this process, also' derives the further advantage of certain 

 fertilizing qualities which each crop produces of itself by the 

 chemical action of such portion of the crop as may be left in 

 the land, or drawn from the atmosphere. 



The educated and observino- farmer can mark out the 

 system of cropping and the application of such fertilizers as 

 are best adapted to the combined uature of the soil and the 

 requirements of his crops. Of course, a still better and more 

 scientific way would be a careful analysis of the soil ; but I 

 confess there are practical difficulties in the way which I hope 

 time and culture will remove. 



Many years ago, a farmer in New Jersey failing to procure 

 a crop of corn from a field which he had taken much pains to 

 cultivate, had the soil analyzed by Prof. Mapes, who found it 

 deficient in chlorine, soda, phosphoric acid, lime, potash and 

 ammonia. He supplied the missing fertilizers ; a compost of 

 common salt restored the chlorine and soda, spent boneblack 

 (a waste from the sugar-refinery) restored the phosphoric 

 acid, Peruvian guano restored potash and ammonia, and a 

 small portion of charcoal-dust and plaster to retain the volatile 

 portions. These chemical fertilizers cost but one dollar and 



