Manures and Fertilizers. 25 



tomatoes, onions, and beet, which receive great benefit from 

 an application of potash even when grown on clay; on such 

 soils, however, potash salts should not be used too frequently 

 on the same plot, as they have a tendency to destroy the tex- 

 ture, causing the soil to lie wet and sticky. Potash is usually 

 deficient on soils containing much sand, gravel, peat or chalk, 

 and these would produce better crops if they received a 

 moderate dressing of potash salts annually. 



LIME is, in varying degrees, an essential constituent of all 

 soils, but there are few which would not benefit by a periodical 

 dressing for the purpose of improving their physical condition 

 as well as developing their fertility. Lime releases the dor- 

 mant plant foods in the soil, rendering them available. Soils 

 which contain an excessive proportion of humus develop acids 

 which are poisonous to plant life ; when lime is applied to 

 such soils these acids are rendered harmless and the soil is 

 made sweet. Lime is necessary as a base to satisfy the re- 

 quirements of certain artificial manures and is a preventive 

 of several fungoid diseases. It is readily dissolved by the 

 carbonic acid gas brought down by rain-water and so is con- 

 stantly being carried away in drainage water ; it also has a 

 tendency to sink in the ground from mechanical reasons, 

 hence the necessity for its frequent renewal. 



MAGNESIA is usually present in most soils in sufficient 

 quantity for all ordinary purposes. It is an important consti- 

 tuent in soils where vines are grown, and where this culture is 

 intended it would be wise to procure an analysis of the soil 

 before planting. Kainit contains about 14 per cent, of sulphate 

 of magnesia, and when this potash salt is used to soil it ensures 

 the presence of sufficient magnesia for all ordinary crops. 



Farmyard Manure is the name given to the liquid and solid 

 excrements of the different animals on the farm, mixed with 

 litter of some kind, usually straw. It varies very much in 

 character and composition, according to the age and .variety 

 of the animals producing it, the kind of food given, the quantity 

 and kind of litter used, and the treatment it receives after 

 being made ; even when the manure produced is of a high 

 fertilizing value it becomes much poorer when allowed to over- 

 heat or by long exposure to rains. 



