FARMYARD MANURE. 31 



them. Provision must consequently be made, sooner or 

 later, to return to the land a part at least of the plant 

 food removed from it, if permanent fertility is to be 

 maintained. Hence the necessity for manuring. 



The most complete return to the land would be ac- 

 complished by manuring it with the excrements of the 

 men and animals consuming the crops. This is partially 

 done by the application of farmyard manure ; but the con- 

 gregation of men in cities, and the difficulty of employing 

 sewage with profit, prevent this plan being thoroughly 

 carried out. The farmer is thus generally obliged to 

 purchase manures for the land in exchange for the crops 

 and stock sold off it. 



On very poor soils it is necessary to make a very com- 

 plete return of all the elements of plant food removed by 

 the crops, but in most soils there is an abundance of some 

 one or more of these elements, and a partial manuring will 

 consequently suffice. With high farming the contribu- 

 tions to the soil may be in excess of the exports, and the 

 land consequently increase in fertility. The nature of 

 the exhaustion resulting from the growth of particular 

 crops, and the economic application of manure to meet 

 their special requirements, will be considered in Chapter 

 IV. ; the losses during a rotation of crops in Chapter Y. ; 

 the losses by the sale of animal products in Chapter VI. 



Farmyard Manure consists of the liquid and solid 

 excrements of the farm stock, plus the litter employed. 

 Its composition will vary according to the character of 

 the animals contributing to it, the quality of their food, 

 and the nature and proportion of the litter. This part of 

 the subject will be discussed in Chapter IX. 



