17 



standard of natural fertility, varying within certain limits, according 

 to the character of the season and the management ; which standard, 

 on a large scale, could practically neither be permanently reduced nor 

 increased by cultivation. Such lands are said to be " out of condi- 

 tion." 



Of course, it must be borne in mind that these observations apply to 

 actual English farm practice and the term must not be pushed to any 

 great extreme. 



ACQUIRED OR TEMPORARY FERTILITY. 



A land is said to be u in good condition" when by the application 

 of manure its permanent fertility is raised so as to produce larger crops, 

 due to the accumulation within the soil of suitable plant food derived 

 from the manure, which may be reduced or entirely withdrawn by the 

 crops. But since it is the minimum of any one essential ingredient 

 and not the maximum of the others which is the measure of fertility, a 

 soil may become exhausted for one plant yet still contain an abundant 

 food supply for another plant whose food requirements are different. 

 Thus a rotation of crops will defer the period of exhaustion. A poor 

 soil is sooner reduced to sterility than a rich one, a shallow soil would 

 fail sooner than a deep one, and a light soil sooner than a stiff one. As 

 only about 1 per cent, of a soil is in a fit condition at any moment for 

 plant food, an immense store of nourishment is contained in most soils 

 in a passive condition, which gradually becomes available.* 



IMPROVEMENT OF THE SOIL. 



The improvement of the soil by tillage, drainage, irrigation, liming, 

 and the application of manures, does not enter into the subject of this 

 report, and the reader in quest of such information is referred to any 

 of the standard works on agriculture, where these subjects are treated 

 in full detail. 



THE MECHANICAL ANALYSIS OF SOIL. 



At one time great stress was laid upon the mechanical analysis of a 

 soil, and chemists were told that more depended on it than on the chemi- 

 cal composition, but nowadays, whilst a knowledge of its physical con- 

 dition is a great help in studying the nature of a soil, still its chemical 

 analysis is of more importance. 



Of the great number of apparatus proposed to effect the mechanical 

 analysis of soils, all labor under more or less objections, and the same 

 soil submitted to different processes yields most diverse results. 



*The Soil of the Farm. 

 13735 No. 10 2 



