VERMONT AGRICULTURAL REPORT. 33 



the main agencies at work at the present time in the preparation of 

 available plant food in the soil. This can only be serviceable in 

 plant growth if it is in solution. The relationship of soil air 

 in opening up the soil and rendering it permeable to water; the 

 relationship of water to solution ; and the relationship of warmth 

 to ease of solution are all so well known as to need no remark. 

 A dense and compact soil, being but slowly penetrated by water, 

 yields its plant food but slowly thereunto and successful growth 

 does not occur. Per contra, from a too open and porous soil 

 the water rapidly removes such plant food as is soluble and the 

 crop starves. The ills which follow in the train of over supplies 

 or under supplies of water are well appreciated, as are also those 

 which ensue from a late spring (too little warmth) or a pro- 

 longed drought (too much warmth with too little water). 



3. Biological Content. 



The countless myriads of micro-organisms which live in the 

 soil, though until recently unknown, and their functions but 

 partially understood, are as important factors in soil fertility as 

 are its chemical constituents or its physical characteristics. The 

 modern concept of the soil is that it is a living entity rather than 

 a dead mass ; that it is a workshop rather than a storehouse, or, 

 rather, a workshop in a storehouse wherein the tiny plants, too 

 small to be seen save with the aid of the microscope, are actively 

 at work transforming raw materials into available plant food, 

 reducing the relatively complex dead animal and vegetable matter, 

 manure, stubble, roots, humus, leaf mold, etc., into simple forms 

 suited for plant nutrition. 



These hosts of helpers are as truly plants as are the corn and 

 clover which, because of their busy activities, are enabled to grow. 

 They need air and water and warmth as do those of a larger 

 growth. If either of these are lacking their growth is hindered 

 or ceases. Since their function, viewed from the standpoint of 

 soil management, is the development of available plant food from 

 the soil, and since they are important though not the sole agencies 

 to that end, it follows that such soil conditions as favor their 

 growth enhance, and such as retard their multiplication lessens 

 the crop producing power of the soil. These favoring and re- 

 tarding conditions are not of a chemical nature, but physical in 

 their character; from which it follows that bags of "phosphate" 

 will not prove a cure all. Such a procedure simply substitutes 

 added plant food for that which might be developed by natural 

 means from stores already present in the soil. He who prepares 

 a good seed bed, who lightens, aerates and pulverizes the soil, pro- 



