192 THE SYSTEM OF FAEM-YARD MANURING. 



state into wliich the field lias been brouglit by the pre- 

 ceding crop. 



In hilly districts, a northern or southern aspect makes 

 a difference in the comparative character of two fields ; so 

 too does the height above the sea, on which the quantity 

 of the fall of rain depends. A fall of rain received at a 

 more favourable time by one field than by another makes 

 a difference in the amount of produce, even though the 

 condition of the soil be the same in both fields. 



Lastly, in judging, in the manner indicated, of the state 

 and condition of a field, the weather dming the preceding 

 year must be taken into account. 



The crop produced by a field in a year is always the 

 maximum crop which it can yield under the conditions 

 given : under more favourable external circumstances, 

 that is, with better weather, the field would have fiir- 

 nished a greater crop ; under more unfavourable ciixum- 

 stances, a smaller, always corresponding to the condition 

 of the soil. 



By the production of larger crops, in consequence of 

 favourable weather, the field loses a comparatively greater 

 amount of nutritive substances, and the subsequent harvests 

 show a dechne ; just as, on the other hand, deficient 

 crops will act upon the jield of subsequent years, as a 

 fallow year with half-manuring does, that is, the crops 

 coming after bad years will turn out better, even in 

 ordinary weather. 



The relative proportions of corn and straw, in a crop of 

 cereals, are altered by a continuance of dry or wet weather. 

 Permanent wet, combined with a high temperature, 

 favours the developement of leaves, stalks and roots ; and 

 as the plant goes on growing, the materials intended for 

 the production of seed are used for the formation of new 

 shoots, and thus the seed crop is diminished. 



