Mr. Johnson on Saline Manures. 315 



dunghill loses much of its fertilizing properties, its salts and 

 other soluble properties being thus washed out. 



Chalk (the carbonate of lime of chemists) is used in various 

 parts of England to a veiy large extent ; and as it is found in 

 the straw of various cultivated grasses in very considerable 

 proportions, there is no doubt of its being absorbed by the 

 plant as an actual nourishment or food. 



There is another reason why chalk is so valuable a consti- 

 tuent part of the soil — its attraction for atmospheric moisture ; 

 the turf on a chalk-hill is sure to preserve its verdure in the 

 driest seasons. 



On some retentive soils, however, chalk is sometimes added, 

 merely to supply a deficiency in the component parts of the 

 soil, or to neutralize acid matters ; and, in many cases, I have 

 no doubt much more chalk is applied than is really needed. I 

 am convinced that, were it properly reduced to a powder, that 

 it might then be spread so evenly and finely over the soil as to 

 produce a given result with one-fourth the usual quantity. 



Gypsum (sulphate of lime) probably operates as a manure 

 by entering into the composition of the plant; for its applica- 

 tion does not produce beneficial effects when it is applied to 

 any of those cultivated grasses which do not contain it in sen- 

 sible quantities ; its successful use, therefore, has been con- 

 fined to lucern, red clover, and sainfoin, all of which contain 

 a considerable quantity of sulphate of lime. 



Many farmers, from an ignorance of these facts, have been 

 induced to waste much time and expense in its useless appli- 

 cation to wheat, barley, and other crops, in which it never 

 appears in sensible proportions. 



Bone-dust, though partly a saline manure, (phosphate and 

 carbonate of lime,) is a more compound fertilizer than any 

 I have mentioned ; its constituents enter into the composition 

 of the plant, and it abounds with oily and gelatinous matters. 



The whole being very finely divided, it speedily shows its 

 good effects, which are perceivable for several succeeding 

 crops : this manure is employed in the north of England at 

 the rate of from forty to sixty bushels per acre ; and I have 

 every reason to believe that it would be judiciously combined 

 with common salt, the last of the saline manures I propose to 

 mention. 



