Mabch 12, 1908. 



The Weekly Florists' Review^ 



can be largely attained or overcome, as 

 the case may be. The mechanical con- 

 sistency of the soil can be produced 

 by a proper combination of sand, of 

 compost, leaf-mold, peat, loam and ma- 

 nure, depending upon the ideal to be at- 

 tained. The available plant food can be 

 supplied tjirough the use of thoroughly 

 decomposed manure, of nitrates, potash 

 salts and the phosphates. 



In general, however, it should be the 

 aim to combine the ingredients entering 

 into a compost several months in ad- 

 vance of the time when it is to be used 

 in the greenhouse, in order that nature 

 may have opportunity to prepare the ma- 

 terials contained in it for use by the 

 plant. Comparatively few of the so- 

 called fertilizers which are upon the mar- 

 ket can be added to the soil and give 

 immediate assistance to the plant. The 

 soil must have an opportunity to, as it 

 were, digest and assimilate these ma- 

 terials before they become of the great- 

 est importance to the plant, and in this 

 work the soil is assisted by the bacteria 

 which it contains. 



Beneficial Work of Bacteria. 



No one should become agitated from 

 the use of the word "bacteria," for we 

 shall have much to say of it farther on. 

 In other words, the materials which are 

 to be combined in the greenhouse soil 

 should be thoroughly composted before 

 they are used in the benches or in the 

 pots. The importance of this is made 

 clear by the fact that every milligram of 

 soil contains between 30,000 and 1,500,- 

 000 minute organisms which derive the 

 means of their existence from the ma- 

 terials in the soil. The personnel of this 

 great population is constantly changing. 

 Every minute sees a new generation 

 brought into existence and an old one 

 pass away; hence the remark, "The soil 

 is the cemetery of the ages." Millions 

 upon millions of generations of minute 

 organisms are constantly passing in this 

 great world beneath our feet. In natural 

 soils these teeming myriads are found 

 chiefly within the first four feet of the 

 earth's crust, and the top soil, which we 

 cultivate and which is not more than a 

 foot in depth, contains by far the great- 

 est portion of this soil population. This 

 fact is of interest to us because the soil 

 bacteria are of all types and classes, 

 those which are beneficial and those 

 which are injurious to crops, to man and 

 to animals, and it is fortunate that this 

 population is confined to the surface soil 

 and that the water-bearing strata of the 

 earth are comparatively free from them. 

 In other words, the water of the soil, 

 ' drawn from a stratum ten or more feet 

 below the surface, is comparatively free 

 from contamination by soil bacteria or 

 surface bacteria, provided there is no 

 surface drainage to it; hence the value 

 of the deeper soil providing an uncon- 

 genial place for these organisms. 



The fact that so great a number of 

 these organisms exist in the upper layer 

 of the soil is due to the presence of de- 

 caying organic matter. Sandy soils con- 

 tain fewer bacteria than clay soils, and 

 the soils in which there is much decay- 

 ing matter contain the greatest number. 

 These organisms which are of impor- 

 tance to agriculture, known as soil bac- 

 teria, are able to transform the inert 

 plant food in the rock particles, in the 

 decaying vegetation and in the decaying 

 animal forms into such shape as makes 

 it available for the next generation of 

 plants. These little organisms are the 



Dracaena Bronze Beauty. 



intermediaries between the past and the 

 future generations that live upon the soil. 

 In soils to which new supplies of organic 

 matter are not frequently added these 

 organisms, after years of continuous ac- 

 tion, deplete the quantity of humus con- 

 tained, so that it has been found that 

 the rich prairie soils when taken up for 

 agricultural purposes may contain as 

 high as twenty per cent of humus, and 

 supply was reduced to two or two and 

 one-half per cent. 



Action of Lime and Gypsum. 



An important function which these 

 organisms play in cultivated soil is to 

 bring the organic forms of nitrogen 

 into forms available for plant use, which 

 is that of nitrates. "Without going into 

 the discussion of the methods by which 

 this is accomplished, it is sufficient to 

 say that these organisms thrive best in 

 soils where there is an abundant supply 

 of moist organic matter which does not 

 become highly acid. The benefits from 

 the use of lime, gypsum and other ma- 

 terials which correct acidity may largely 

 be attributed to the benefit which they 

 work upon these minute organisms in 

 the soil. The alkaline condition brought 

 about by the application of lime and 

 gypsum gives a more congenial home for 

 the bacteria than do the acid conditions 

 which are brought about by fermentation 

 and decomposition. These bacteria work 

 only upon the products of decomposition 

 and fermentation, and transform them 

 into those forms of nitrogen which are 



available to plants. All of these steps 

 are essential, but if one is excessive, the 

 other suffers in consequence. This opera- 

 tion of transforming the products of 

 decomposition and combustion is called 

 nitrification. 



If our compost heaps are made some- 

 what in advance of the period at which 

 the soil is to be used in the greenhouse, 

 opportunity will be given for this digest- 

 ive operation, which is carried on by the 

 soil bacteria, to take place. Nitrifica- 

 tion will take place, but in order that 

 nitrification may go on it is essential 

 that the compost heap be made not too 

 deep, and that it be kept moist rather 

 than dry. Excessive heat is detrimental 

 to the existence of bacteria, and causes 

 a cessation of nitrification. ExcesslTe 

 cold operates in the same way. The 

 height of the work is accomplished under 

 July and August heat conditions, with 

 the normal moisture. Excessive moisture 

 is quite as detrimental as lack of mois- 

 ture, so that attention should be given 

 to the condition of the soil while it is 

 in the compost heap in order to make an 

 ideal greenhouse soil. 



Determining Soil Requirements. 



This brief sketch will serve to illus- 

 trate the important bearing which these 

 unseen and to most of us unknown or- 

 ganisms )iave upon the important work 

 of our lives, that of making a livelihood. 

 And, strange as it may seem, it is only 

 within comparatively few years that 

 science has known anything at all of the 



