ARABLE SOILS ABSORB MINERAL MATTERS. 135 



In a fertile soil tillage and manuring have a definite 

 relation to one another. If, after a rich harvest, the 

 field is prepared by tillage alone to produce a similar 

 rich crop in the next year, that is, if the mechanical 

 means are sufficient to distribute the store of nutritive 

 substances so uniformly that the plants of the following 

 season will find as much nutriment in all parts of the 

 soil as during the last, any further supply of mineral 

 constituents by manuring would be mere waste ; but, 

 where a field is not in that condition, the deficiency 

 must be supplied by manure, in order to restore the 

 original power of production. Thus, in a certain sense, 

 the mechanical operations of tillage and of manure are 

 supplementary to one another. 



Of two similar fields, manured in exactly the same 

 way, if the one has been well tilled, and the other bad- 

 ly tilled, the former will yield a richer crop, i. e. the 

 manure seems to have a better effect upon this than 

 upon the badly tilled field. 



If one of two farmers knows his land better, and 

 cultivates it more judiciously than the other, the former 

 will, in a given time, obtain as good crops with less 

 manure, or richer crops with the same quantity of 

 manure. 



All these facts should be considered in estimating 

 the value of manuring agents; but, as science has no 

 standard for measuring the results of the mechanical 

 operations of tillage, this cannot be taken into account 

 here, and we must confine ourselves to that which can 

 be scientifically measured and compared. 



When two fields are equally rich in nutritive sub- 

 stances', it often happens that the one, by tillage alone, 

 or by tillage combined with manuring, will be ""brought 

 much sooner than the other into a condition to yield a 

 succession of remunerative crops of cereal or other 

 plants. 



On a light sandy soil, all kinds of manure act more 

 rapidly and effectively than on clay. The sand is more 

 grateful, say the farmers, for the manure bestowed 

 upon it, and yields a more abundant return than other 



