14 Fish Manures, 



of repose in order that a store of more soluble matters may be form- 

 ed. Ilence the utility of fallows. 



In my analysis of the soils of the Richelieu valley, in the Report 

 for 1850, pp. 79-90, I have shown, by comparing the virgin soils 

 with those exhausted by continued crops of wheat during fifty 

 years, that the proportions of phosphoric acid and magnesia, ele- 

 ments which are contained in large quantities in this grain, have 

 been greatly diminished, but the soil still contains as much phos- 

 phate as it has lost, and this only requires to be rendered soluble 

 in order to be available to vegetation. 



In forests and untilled lands the conditions of a healthy vegeta- 

 ble growth are seldom wanting; the soil affords in sufficient quan- 

 tity all the chemical elements required, while the leaves and seeds 

 which annually fall and decay, give back to the earth a grea 

 proportion of the elements which it has yielded. In this way the 

 only loss of mineral matter is that which remains stored up in the 

 growing wood or is removed by waters from the soil. Far dif- 

 ferent is the case in cultivated fields, since in the shape of corn, 

 of fat cattle, and the products of the dairy, we remove from the 

 soil its phosphates, alkalies and nitrogen, and send them to foreign 

 markets. The effect of tillage becomes doubly exhaustive when 

 by artificial means we stimulate vegetation without furnishing all 

 the materials required for the growing plants. Such is the effect 

 of many special manures, which while the3 r supply certain elements, 

 enable the plants to remove the others more rapidly from the soil. 

 A partial exhaustion of the soil results likewise from repeated 

 crops of the same kind ; for the elements of which the cereals 

 require the largest quantity are taken in smaller proportions by 

 green crops, and reciprocally, so that by judicious alternations the 

 balance between the different mineral inoredients of the soil is 

 preserved. 



One of the great problems in scientific agriculture is to supply 

 to the soil the ammonia and the mineral matters necessary to sup- 

 port an abundant vegetation, and to obtain from various sources 

 these different elements at prices which will permit of their being 

 economically made use of. Nowhere but in the manure of the 

 stable and farm-yard can we find combined all the fertilizing ele- 

 ments required, but several of them may be very cheaply procured. 

 Thus lime and magnesia are abundant in the shape of marl and 

 limestones ; soda is readily obtained, together with chlorine, in 

 common salt ; while gypsum or plaster of Paris supplies at a low 



