PEAT AS AN ABSORBENT AND AS A FERTILIZER. 99 



vegetation that whatever manure appropriates these elements to the 

 greatest extent may be regarded as the most beneficial. Four-fifths 

 of all growth comes from them. Some chemists have contended 

 that water is the onl^- dressing needed ; that the overflows of the 

 Nile and of our meadow streams, which annuallj' enrich the lands, 

 bring to tliem nothing verj^ fertilizing except the water ; and that 

 the amount of water retained by a manure is a good test of its 

 quality, as the air is constantly co-operating with it to prepare the 

 needed food. We cannot well over-estimate the importance of 

 either of these elements. Although onl}^ one-fifth part of our com- 

 mon air consists of oxygen, yet so essential is the supply of oxj'gen 

 in nature, that more than one-half of the weight of all the solid 

 rocks of the globe is composed of it ; without it, there could be 

 neither life nor decay. Oxidation and decay cannot proceed 

 without it, and they are the only sources from which come the 

 renewal and supply of all vegetable matter. Decaj' is a species of 

 oxidation or slow combustion — a consuming or burning process, 

 whereby a change is effected as by heat ; the color of a substance is 

 changed and darkened by it, as if slightly charred, and finally it 

 falls to powder. Too much water will check this decomposition, 

 but a good quantit}' is needful. 



Peat is fertilizing matter undecomposed, or matters in which 

 decomposition may have commenced. Indeed, fermentation is 

 necessary to bring out its virtue. Generally, the blacker the peat, 

 the better it is ; and that kept longest is best, provided it has been 

 kept out of the bog and has not been fire-fanged or flooded. But 

 it must be decomposed before it is available for plants ; fresh peat 

 is not to be ploughed under and immediately mixed with the earth. 

 A peat-bog may be thoroughly drained and ploughed, 3'et, rich as it 

 is in material, the first year's product will be disappointment and 

 failure, for the soil will be sour and undecomposed, and in no con- 

 dition for plant growth. The application of plaster of Paris, or 

 lime, in moderate quantit}', would be beneficial in such ground by 

 decomposing the soil and bringing into activity its humus and in- 

 soluble matter. But if the soil is too rich in humus, there is danger 

 of forming thereby an injurious humate of lime, and also of setting 

 free too much corrosive sulphuric acid. On cla3'ey grounds, ex- 

 cepting in warm and wet seasons, gypsum is of little account. On 

 sandy or gravelly lands, applied just before or after a rain, it 

 succeeds well. It must not, however, be often repeated or long 



