N... (1. DEPARTMENT OP AGRICULTURE. 329 



mailable yiaiil loud is convei-lcd iiiLu uNuilubk-. LLuiuus, because of 

 its retentive power, decreases the loss of nitrates by leaching. 

 Humus fixes and holds ammonia in the soil until it is converted into 

 nitrate nitrogen, a form which can be used by the growing plants, 

 llumus ordinarily contains from o to 12 per cent, of nitrogen, making 

 it of inestimable value as a source of this element, llumus also 

 contains potasli, lime, phosphoric acid and other essential elements 

 of plant food. Humus is necessary for the life and work of micro- 

 organisms which must be present in large numbers to insure a pro- 

 ductive soil. ?>o great and varied are the good influences of humus 

 that its importance as a factor of soil fertility cannot be emphasized 

 too highly. When any soil is cropped with grain or plants requir- 

 ing clean tillage, without manuring or plowing under of green crops, 

 the supply of decaying vegetable matter rapidly decreases and the 

 fertility of the soil diminishes in proportion to the decrease of 

 organic matter. Every possible means should, therefore, be em- 

 ployed to maintain the supply of humus. This may be done by the 

 liberal use of farm manures, green manuring and a proper rotation 

 of crops. 



• BACTERIA OF THE SOIL. 



In this age of ad\ anced agricultural science, we hear much of the 

 great work bacteria are doing for the farmer. Even the institute 

 soloists are beginning to sing about microbes in the air, and 

 microbes everywhere. The Experiment Stations and State Depart- 

 ments of Agriculture have taken up a detailed study of the bacteria 

 of the soil, and the literature on the subject is profuse. Our own 

 State Department of Agriculture should be commended for its quite 

 recent bulletin on "Soil Bacteria in their Relation to Agriculture." 

 This treatise should be carefully studied by every farmer of our 

 Commonwealth, for no cultivator can work intelligently without a 

 knowledge of the micro-organisms of the soil. 



Not many years ago the soil was regarded as simply dead, inert 

 matter, entirely devoid of life, except the root of the crops which 

 were being produced thereon. But scientific study and research 

 show that the soil is permeated with living beings; that the soil is a 

 veritable workshop or laboratory where myriads of micro-organisms 

 are constantly engaged, when the conditions are favorable, in con- 

 verting the hard, insoluble, unavailable particles into forms that 

 the plant can use. There is a most intimate relationship existing 

 between the lower and tlie higher forms of })lant life. The lower 

 forms digest the food for the higher so that it can be assimilated and 

 utilized. 



The action of bacteria in the formation of nitrates is especially 

 important to growing x)lants. Plants derive most of their nitro- 

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