in.] CAUSS 01? FERTILITY. 37 



a complete supply of food, and it exists in a condition 

 favourable for vegetable growth, and we also have it 

 situated in a climate suitable for the crop to be grown. 

 Such a soil properly cultivated constitutes a good and 

 fertile soil. If either of these conditions is wanting, 

 then it ceases to be good and productive land. You 

 will observe that no one condition is sufficient to make 

 the land productive ; the plant-food must be there, and 

 under such circumstances that the plant can use it, 

 the climate must also be favourable for the crops, and 

 the soil must be well cultivated ; but the absence of 

 any one of these conditions renders the land unpro- 

 ductive and poor for that particular crop. 



CHAPTER IV. 

 FARM MANURES. 



48. The more frequent growth of various crops 

 having been found advantageous, the use of manure 

 is now recognized as absolutely necessary for pre- 

 serving the land in a productive condition. It may 

 be well to see what manures are, and how they accom- 

 plish this work. Much of the vegetable produce 

 grown upon the land has to be kept upon the farm, 

 and "reduced into such a condition that it can be 

 again added to the soil as manure. If we take a 

 crop of wheat as an example, the corn is separated 

 from the straw, and the corn having been sent to 

 market, the straw is used for stock, and finds its way 

 to the manure heap after it has been so used. 

 Other crops, such as those known as root crops 

 mangels, turnips, swedes are consumed by stock on 

 the farm ; and the green crops, such as clover, vetches, 

 rape, mustard, &c., are similarly used. These crops 

 are therefore used for a twofold object first, to 

 produce meat, wool, milk, cheese and similar market- 



