ON MANURES. 229 



Soap Ashes are composed of lime (converted again into chalk) and 

 soda This is a good and lasting dressing on a dry sandy soil. 



Hough Potash, from saltpetre works, is the best of all dressings ; it 

 is the vegetable itself concentrated in a state ready to enter at once 

 into the fibres of young roots of plants when aided by water. 



Lime, when thrown over land, is quickly converted again into chalk 

 by imbibing from the air that acid which had been driven off by fire : 

 hence chalk is as good if put on the land in the winter, because the 

 frost, acting on the water in it, expands and crumbles the article to pieces. 

 Salt is a soda in union with an acid, and acts on land in the same 

 manner as many other manures, by holding moisture for the service of 

 vegetation ; but the article of common salt does not enter so much into 

 the composition of land vegetables as the salt of potash, that is, salt- 

 petre, or vegetable alkali, as it is called. 



Cheap efficacious Manure.— Raise a platform of earth on the head- 

 land of a field, eight inches high, and of any width and length, accord- 

 in^ to the quantity wanted. On the first stratum of earth lay a thin 

 stratum of lime from the kiln ; dissolve or slake this with salt brine 

 from the rose of a watering pot ; add immediately another layer eight 

 inches thick of earth, then lime and brine as before, carrying it to any 

 convenient height. In a week it should be turned over, carefully 

 broken and mixed, so that the mass may be thoroughly incorporated. 

 This compost has been used in Ireland, has doubled the crops of potatoes 

 and cabbages, and is superior to stable dung. 



Gypsum is a dressing used with a variety of effects on different lands, 

 and for different purposes ; it is a lime in union with sulphur, being a 

 refuse from plaster-makers. Those crops which are cut green take up 

 gypsum, which constitutes a part of their substance, such as sainfoin, 

 clover, lucern, peas, tares, and such like crops. To these this mineral 

 dressing will be good ; but it is injurious on a chalky land, and when 

 animal and vegetable manures are easily obtained it is not worth using, 

 for they yield a sufficiency of gypsum to the soil. Sir H. Davy con- 

 sidered that an acre of tares took up several pounds of gypsum. 



Bone Dust is now a very favourite dressing for turnips, and, indeed, 

 many other crops ; it is principally composed of lime and phosphorus, 

 which readily enter into the composition of grain and all grasses. A 

 portion of lime and phosphorus is also found in all milk, and goes to 

 form the bones of young animals which suck ; the staler the milk, the 

 less phosphorate of lime is there in it. This bone-dressing for land is 

 a very expensive article, and should be cautiously used. Coal-ashes, 

 especially if laid under dung-heaps, are an excellent dressing for clays, 

 by opening and enriching the soil, and, like soot, impart a carbon or 

 charcoal to the soil, of which all clays are deficient. 



In all tiiese manures we find lime an active principle, except in the 

 salt dressings. Lime imbibes carbon, which is the woody principle, 

 and also holds moisture for the service of vegetation. If we cannot 

 procure large quantities of these manures, we must entice air and water 

 to the roots of plants by every means in our power ; and this may be 

 done with the greatest facility by repeated movings of the surface, a 

 hoeing being equal to a shower of rain. 



