138 Report on Trials of Plows. 



cannot take up any more. If we now remove the bone and biuy 

 it in unsaturated earth, another portion will be dissolved, and the 

 soil contiguous to it will be saturated. We may thus, by suc- 

 cessive removals and burials of the bone until it is wholly dissolved, 

 render many times more soil fertile than if it had been left steadily 

 in one place. There is no soil known through which the fertile 

 matters are evenly diffused, and hence benefit must always result 

 from mixing together the fertile and unfertile portions. 



This is one of the objects sought to be accomplished by plow- 

 ing land; it is because the spade accomplishes this more perfectly 

 than any form of plow yet known to us, that so much larger 

 crops can be obtained when that method of tillage is used. 



Plows differ very widely in their power to mix soils together. 

 Those which invert the furrow completely hardly mix it at all. 

 Those which leave the furrow at an angle of 45 deg. mix it more 

 intimately. Those which take a narrow furrow do it still more 

 completely than those that take a broad one, and those that turn 

 a furrow in two successive portions, as the sod and subsoil plow, 

 intermingle the particles of the soil more perfectly than when it 

 is turned in one mass. 



It is obvious, from these considerations, that by bringing into 

 contact with each other the particles of soil which had previously 

 >>een separated, we increase its fertility, and therefore those kinds 

 of plows which accomplish this object most perfectly, other things 

 being equal, are to receive the preference. 



Second — A very little reflection will satisfy a former that he 

 may have abundant elements of fertility in his soil, yet he will 

 derive no benefit from them, because they are locked up by affini- 

 ties which the rootlets of the plant cannot overcome. Thus, one 

 ton of farm yard manure may be spread over a given area of soil, 

 and one ton of coal spread over an equal contiguous area. The 

 plants growing in the soil covered withhnanure will be abundant ly 

 supplied with ammonia, while those growing in the soil covered 

 with the coal will receive none, and cease to grow in conse- 

 quence. If now we ascertain by analysis the amount of ammonia 

 contained in each, we find that one ton of the former contains 

 17,4 pounds of ammonia, while a ton of the latter contains 47. G 

 pounds, or nearly three times as much as the manure contained. 



The important practical question, therefore, for the farmer to 

 ask is, not how much plant nulriniont is contained in his soil, but 



