42 MASSACHUSETTS AGRICULTURE. 



fertilizer can be active till absolutely dissolved, and hence so 

 many apparent or real failures in the use of mineral fertilizers. 



It is estimated that the supply of ten pounds to the acre 

 of phosphate is imparted to the soil during the live summer 

 months of average rainfall (about two thousand tons to the 

 acre) ("which furnishes, perhaps, a sufficient supply for an 

 annual crop of wheat, but would be insufficient for most other 

 crops. Hence the general usefulness and utility of bone-dust, 

 furnishing as it does so large a supply of phosphate and 

 magnesia, so essential to all crops, and being less adulterated 

 than most of the commercial manures. 



The soil of the earth is shallow, as a general rule. The 

 average depth does not exceed one foot over the entire globe. 

 It is, therefore, just fitted for the convenience of the plough 

 and the spade. Beyond this depth, without special cultiva- 

 tion, plants find no nourishment. Arable soil is the result of 

 a process of chemical action which disintegrates rocks by the 

 influence of water and atmospheric action. The earth thus 

 formed, having nourished vegetables and animals, which in 

 turn perish and decay, producing what we call soil, is more 

 or less productive as it becomes charged with the gases of the 

 atmosphere. The principal elements are silica or sand, 

 alumina or claj'^ and lime, making a composition of nearly 

 ninety-five per cent, of the whole soil ; magnesia, soda and 

 oxide of iron with manganese, sulphur, phosphorus and 

 chlorine making up the other five per cent. You will there- 

 fore perceive how small a portion of the soil is constituted 

 of these chemical elements, and yet the land would be unpi-o- 

 ductive without the relative quantity of each of them. iS^or 

 will nature, as a general rule, permit the abundance or excess 

 of one to supply the deficiency of another. Hence the 

 importance to the practical farmer of a well-defined analysis 

 of the soil, as well as the chemical qualities and quantities of 

 the fertilizers to the proposed crop. 



It cannot be expected, in the present low state of practical 

 aofriculture, that these investigations will be brought to bear 

 to any great extent on our farms, but we must approximate 

 to them as zealously as the nature of the case will admit. 

 The ambitious archer will not hit the sun, but his arrow will 

 reach a greater altitude by trying to do so. 



