fc 



120 THE PRINCIPLES OF 



looked. We hear of the pulverizing effect of frost, but we 

 hear very little of the pulverizing effect of the solar rays, 

 and of the alternations between a moist and a dry condition, 

 which assuredly will break down tenacious clays even in the 

 summer. A judicious waiting for rain is a guiding principle 

 to the clay land farmer. He ploughs up his stiff' clay land, 

 and there lets it " make " or pulverize under the combined 

 action of the changing temperature between night and day, 

 the scorching effect of the sun, and the ameliorating and 

 mellowing influence of thunderstorms, or of sharp showers 

 of rain. In \vorking a bare fallow, for example, which is a 

 system of cultivation still in vogue on certain classes of clay 

 land, the object is to produce the roughest possible condition 

 of soil at midsummer that is the way to produce an efficient 

 bare fallow ; the ground being then strewn over with large 

 clods, sometimes described as " nags' heads." These great 

 clods are rumbled and tumbled about by heavy drags, or it 

 may be by other toothed cultivating implements, and during 

 the period between Midsummer Day and the 1st of August 

 they crumble down under the influence of tillage implements, 

 assisted by showers, thunderstorms, and these invaluable 

 changes of temperature and pulverizing influences which are 

 constantly assisting the farmer if he will only allow them ; 

 so that, by the end of August, we find instead of a surface 

 covered with " nags' heads," we have a tilth composed partly 

 of loose material calculated to assist in the germination of 

 seed, interspersed with moderate-sized clods, and that I take 

 to be the most suitable condition of clay soil for wheat- 

 sowing, a condition in which there is a sufficient amount of 

 fine soil, and intermixed with it, and upon the surface of 

 it, a nice round clod. 



When the wheat is drilled we have then the best possible 

 safeguard against its being " thrown out " by frost, an evil 

 which takes place if the surface is too fine. But the gradual 



