13 



action, so that under such a system it is certain the crop will 

 continually diminish in quantity and quality, until at last the 

 land will cease to produce. 



As this result becomes manifest by experience, remedies are 

 sought, and the system of " bare " fallowing was adopted ; for 

 by allowing the land to remaiu idle for one or two years after 

 one or two crops have been gathered, the materials abstracted 

 by the plant are in some measure returned by atmospheric 

 action. 



As this system required a large amount of land prepared for 

 culture, it was not found very profitable, and has been very 

 generally abandoned ; in its place " rotation " has succeeded. 



The principle of rotation rests upon the fact that different 

 plants take from the soil different quantities of its mineral 

 constituents, so that though a soil deficient in some constituent 

 will not grow a plant which requires much of that material, 

 still it will grow and mature other plants, which either do not 

 use that constituent, or use it in less quantity. 



In " rotation" we grow plants whose demand for some of the 

 materials of the soil is less than were the preceding, so that by 

 the time the rotation is completed, the materials required for 

 the first crop have been restored by atmospheric action. 



In the third system, or the system of " high-farming," it is 

 sought to raise the greatest amount of fruit per acre, and conse- 

 quently to carry off from the soil the greatest amount of avail- 

 able substances which form the seed. 



The increase of the weed of the plant is of no importance, 

 hence it will be seen that a morbid growth is demanded, that is, 

 a greater amount of seed should be yielded than is normally 

 proportioned to the weed. 



In this system, therefore, the plant must be furnished not 

 only with a greater amount of ash and air-food than is normal- 

 ly present, but they must also be so proportioned as to produce 

 this morbid growth of fruit. This is done by manuring; we 

 must stimulate the plant to assimilate those materials which 

 compose the fruit, and those materials must be supplied in an 

 easily available state, and in an abundant quantity ; if, there- 

 fore, we apply to the soil a compound of air and of ash-food in 

 just proportions, and in an easily available (that is, highly solu- 

 ble) state, all the conditions of " high-farming" are fulfilled. 



It is evident that we cannot increase the atmosphere, but we 

 can add it to the soil, either by growing certain crops, as peas 

 and clover, which absorb large quantities of air food from the 

 atmosphere, and then plough them in; or, more quickly, we can 

 at once apply to the soil nitrogenous compounds, as the nitrates, 

 ammoniacal salts, etc. The system, then, of " high-farming " 

 demands an application yearly to the soil of a mixture or ma- 

 nure composed of the ash-food of the plant, and especially of 

 the seed in a soluble state, together with some nitrogenous 



