26 AGRICULTURE 



mould, green manure, and the like. Such 

 material, by binding together the particles of 

 sand, does much to diminish the excessively 

 non-cohesive condition of sandy soil. 



In the case of strong clay, which is too 

 cohesive, much may be done to produce a more 

 crumbly consistency by early ploughing, and 

 the exposure of the rough furrow to the action 

 of winter frost and spring sun. Even the 

 most plastic clay crumbles down in the course 

 of the winter ; and in spring, if the con- 

 ditions are sufficiently dry, it may be almost 

 mealy in character. The alternations of tem- 

 perature during winter and spring, the dis- 

 integrating action of frost, the corroding 

 effects of the oxygen and carbonic acid of 

 the atmosphere, and other natural agents, 

 have been at work, mellowing the soil, and 

 producing what every farmer likes to find 

 in abundance in spring, a good tilth. But 

 this desirable condition of the soil can be very 

 easily destroyed by injudicious treatment, 

 and every experienced farmer and gardener 

 knows that the most beautifully tilthy soil 

 may be converted into a plastic, sticky 

 mass, too cohesive when wet and too hard 

 when dry, if strong land is worked when out of 

 condition. It is in spring that one must 

 be most careful, at a time, namely, when the 



